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-rw-r--r--kernel/Makefile4
-rw-r--r--kernel/exit.c1
-rw-r--r--kernel/fork.c5
-rw-r--r--kernel/rcuclassic.c807
-rw-r--r--kernel/rcupdate.c44
-rw-r--r--kernel/rcupreempt.c1539
-rw-r--r--kernel/rcupreempt_trace.c334
-rw-r--r--kernel/rcutorture.c202
-rw-r--r--kernel/rcutree.c273
-rw-r--r--kernel/rcutree.h253
-rw-r--r--kernel/rcutree_plugin.h532
-rw-r--r--kernel/rcutree_trace.c88
-rw-r--r--kernel/sched.c131
-rw-r--r--kernel/softirq.c4
-rw-r--r--kernel/timer.c3
15 files changed, 1293 insertions, 2927 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index 2093a691f1c2..b833bd5cc127 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -80,11 +80,9 @@ obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o
obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
obj-$(CONFIG_SECCOMP) += seccomp.o
obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
-obj-$(CONFIG_CLASSIC_RCU) += rcuclassic.o
obj-$(CONFIG_TREE_RCU) += rcutree.o
-obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o
+obj-$(CONFIG_TREE_PREEMPT_RCU) += rcutree.o
obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o
-obj-$(CONFIG_PREEMPT_RCU_TRACE) += rcupreempt_trace.o
obj-$(CONFIG_RELAY) += relay.o
obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
diff --git a/kernel/exit.c b/kernel/exit.c
index c98ff7a8025f..ae5d8660ddff 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1014,6 +1014,7 @@ NORET_TYPE void do_exit(long code)
validate_creds_for_do_exit(tsk);
preempt_disable();
+ exit_rcu();
/* causes final put_task_struct in finish_task_switch(). */
tsk->state = TASK_DEAD;
schedule();
diff --git a/kernel/fork.c b/kernel/fork.c
index aab8579c6093..bfee931ee3fb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1007,10 +1007,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
copy_flags(clone_flags, p);
INIT_LIST_HEAD(&p->children);
INIT_LIST_HEAD(&p->sibling);
-#ifdef CONFIG_PREEMPT_RCU
- p->rcu_read_lock_nesting = 0;
- p->rcu_flipctr_idx = 0;
-#endif /* #ifdef CONFIG_PREEMPT_RCU */
+ rcu_copy_process(p);
p->vfork_done = NULL;
spin_lock_init(&p->alloc_lock);
diff --git a/kernel/rcuclassic.c b/kernel/rcuclassic.c
deleted file mode 100644
index 0f2b0b311304..000000000000
--- a/kernel/rcuclassic.c
+++ /dev/null
@@ -1,807 +0,0 @@
-/*
- * Read-Copy Update mechanism for mutual exclusion
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright IBM Corporation, 2001
- *
- * Authors: Dipankar Sarma <dipankar@in.ibm.com>
- * Manfred Spraul <manfred@colorfullife.com>
- *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
- * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
- * Papers:
- * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
- * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
- *
- * For detailed explanation of Read-Copy Update mechanism see -
- * Documentation/RCU
- *
- */
-#include <linux/types.h>
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/spinlock.h>
-#include <linux/smp.h>
-#include <linux/rcupdate.h>
-#include <linux/interrupt.h>
-#include <linux/sched.h>
-#include <asm/atomic.h>
-#include <linux/bitops.h>
-#include <linux/module.h>
-#include <linux/completion.h>
-#include <linux/moduleparam.h>
-#include <linux/percpu.h>
-#include <linux/notifier.h>
-#include <linux/cpu.h>
-#include <linux/mutex.h>
-#include <linux/time.h>
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-static struct lock_class_key rcu_lock_key;
-struct lockdep_map rcu_lock_map =
- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
-EXPORT_SYMBOL_GPL(rcu_lock_map);
-#endif
-
-
-/* Definition for rcupdate control block. */
-static struct rcu_ctrlblk rcu_ctrlblk = {
- .cur = -300,
- .completed = -300,
- .pending = -300,
- .lock = __SPIN_LOCK_UNLOCKED(&rcu_ctrlblk.lock),
- .cpumask = CPU_BITS_NONE,
-};
-
-static struct rcu_ctrlblk rcu_bh_ctrlblk = {
- .cur = -300,
- .completed = -300,
- .pending = -300,
- .lock = __SPIN_LOCK_UNLOCKED(&rcu_bh_ctrlblk.lock),
- .cpumask = CPU_BITS_NONE,
-};
-
-static DEFINE_PER_CPU(struct rcu_data, rcu_data);
-static DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
-
-/*
- * Increment the quiescent state counter.
- * The counter is a bit degenerated: We do not need to know
- * how many quiescent states passed, just if there was at least
- * one since the start of the grace period. Thus just a flag.
- */
-void rcu_qsctr_inc(int cpu)
-{
- struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
- rdp->passed_quiesc = 1;
-}
-
-void rcu_bh_qsctr_inc(int cpu)
-{
- struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
- rdp->passed_quiesc = 1;
-}
-
-static int blimit = 10;
-static int qhimark = 10000;
-static int qlowmark = 100;
-
-#ifdef CONFIG_SMP
-static void force_quiescent_state(struct rcu_data *rdp,
- struct rcu_ctrlblk *rcp)
-{
- int cpu;
- unsigned long flags;
-
- set_need_resched();
- spin_lock_irqsave(&rcp->lock, flags);
- if (unlikely(!rcp->signaled)) {
- rcp->signaled = 1;
- /*
- * Don't send IPI to itself. With irqs disabled,
- * rdp->cpu is the current cpu.
- *
- * cpu_online_mask is updated by the _cpu_down()
- * using __stop_machine(). Since we're in irqs disabled
- * section, __stop_machine() is not exectuting, hence
- * the cpu_online_mask is stable.
- *
- * However, a cpu might have been offlined _just_ before
- * we disabled irqs while entering here.
- * And rcu subsystem might not yet have handled the CPU_DEAD
- * notification, leading to the offlined cpu's bit
- * being set in the rcp->cpumask.
- *
- * Hence cpumask = (rcp->cpumask & cpu_online_mask) to prevent
- * sending smp_reschedule() to an offlined CPU.
- */
- for_each_cpu_and(cpu,
- to_cpumask(rcp->cpumask), cpu_online_mask) {
- if (cpu != rdp->cpu)
- smp_send_reschedule(cpu);
- }
- }
- spin_unlock_irqrestore(&rcp->lock, flags);
-}
-#else
-static inline void force_quiescent_state(struct rcu_data *rdp,
- struct rcu_ctrlblk *rcp)
-{
- set_need_resched();
-}
-#endif
-
-static void __call_rcu(struct rcu_head *head, struct rcu_ctrlblk *rcp,
- struct rcu_data *rdp)
-{
- long batch;
-
- head->next = NULL;
- smp_mb(); /* Read of rcu->cur must happen after any change by caller. */
-
- /*
- * Determine the batch number of this callback.
- *
- * Using ACCESS_ONCE to avoid the following error when gcc eliminates
- * local variable "batch" and emits codes like this:
- * 1) rdp->batch = rcp->cur + 1 # gets old value
- * ......
- * 2)rcu_batch_after(rcp->cur + 1, rdp->batch) # gets new value
- * then [*nxttail[0], *nxttail[1]) may contain callbacks
- * that batch# = rdp->batch, see the comment of struct rcu_data.
- */
- batch = ACCESS_ONCE(rcp->cur) + 1;
-
- if (rdp->nxtlist && rcu_batch_after(batch, rdp->batch)) {
- /* process callbacks */
- rdp->nxttail[0] = rdp->nxttail[1];
- rdp->nxttail[1] = rdp->nxttail[2];
- if (rcu_batch_after(batch - 1, rdp->batch))
- rdp->nxttail[0] = rdp->nxttail[2];
- }
-
- rdp->batch = batch;
- *rdp->nxttail[2] = head;
- rdp->nxttail[2] = &head->next;
-
- if (unlikely(++rdp->qlen > qhimark)) {
- rdp->blimit = INT_MAX;
- force_quiescent_state(rdp, &rcu_ctrlblk);
- }
-}
-
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-
-static void record_gp_stall_check_time(struct rcu_ctrlblk *rcp)
-{
- rcp->gp_start = jiffies;
- rcp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK;
-}
-
-static void print_other_cpu_stall(struct rcu_ctrlblk *rcp)
-{
- int cpu;
- long delta;
- unsigned long flags;
-
- /* Only let one CPU complain about others per time interval. */
-
- spin_lock_irqsave(&rcp->lock, flags);
- delta = jiffies - rcp->jiffies_stall;
- if (delta < 2 || rcp->cur != rcp->completed) {
- spin_unlock_irqrestore(&rcp->lock, flags);
- return;
- }
- rcp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
- spin_unlock_irqrestore(&rcp->lock, flags);
-
- /* OK, time to rat on our buddy... */
-
- printk(KERN_ERR "INFO: RCU detected CPU stalls:");
- for_each_possible_cpu(cpu) {
- if (cpumask_test_cpu(cpu, to_cpumask(rcp->cpumask)))
- printk(" %d", cpu);
- }
- printk(" (detected by %d, t=%ld jiffies)\n",
- smp_processor_id(), (long)(jiffies - rcp->gp_start));
-}
-
-static void print_cpu_stall(struct rcu_ctrlblk *rcp)
-{
- unsigned long flags;
-
- printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu/%lu jiffies)\n",
- smp_processor_id(), jiffies,
- jiffies - rcp->gp_start);
- dump_stack();
- spin_lock_irqsave(&rcp->lock, flags);
- if ((long)(jiffies - rcp->jiffies_stall) >= 0)
- rcp->jiffies_stall =
- jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
- spin_unlock_irqrestore(&rcp->lock, flags);
- set_need_resched(); /* kick ourselves to get things going. */
-}
-
-static void check_cpu_stall(struct rcu_ctrlblk *rcp)
-{
- long delta;
-
- delta = jiffies - rcp->jiffies_stall;
- if (cpumask_test_cpu(smp_processor_id(), to_cpumask(rcp->cpumask)) &&
- delta >= 0) {
-
- /* We haven't checked in, so go dump stack. */
- print_cpu_stall(rcp);
-
- } else if (rcp->cur != rcp->completed && delta >= 2) {
-
- /* They had two seconds to dump stack, so complain. */
- print_other_cpu_stall(rcp);
- }
-}
-
-#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
-static void record_gp_stall_check_time(struct rcu_ctrlblk *rcp)
-{
-}
-
-static inline void check_cpu_stall(struct rcu_ctrlblk *rcp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
-/**
- * call_rcu - Queue an RCU callback for invocation after a grace period.
- * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
- *
- * The update function will be invoked some time after a full grace
- * period elapses, in other words after all currently executing RCU
- * read-side critical sections have completed. RCU read-side critical
- * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
- * and may be nested.
- */
-void call_rcu(struct rcu_head *head,
- void (*func)(struct rcu_head *rcu))
-{
- unsigned long flags;
-
- head->func = func;
- local_irq_save(flags);
- __call_rcu(head, &rcu_ctrlblk, &__get_cpu_var(rcu_data));
- local_irq_restore(flags);
-}
-EXPORT_SYMBOL_GPL(call_rcu);
-
-/**
- * call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
- * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
- *
- * The update function will be invoked some time after a full grace
- * period elapses, in other words after all currently executing RCU
- * read-side critical sections have completed. call_rcu_bh() assumes
- * that the read-side critical sections end on completion of a softirq
- * handler. This means that read-side critical sections in process
- * context must not be interrupted by softirqs. This interface is to be
- * used when most of the read-side critical sections are in softirq context.
- * RCU read-side critical sections are delimited by rcu_read_lock() and
- * rcu_read_unlock(), * if in interrupt context or rcu_read_lock_bh()
- * and rcu_read_unlock_bh(), if in process context. These may be nested.
- */
-void call_rcu_bh(struct rcu_head *head,
- void (*func)(struct rcu_head *rcu))
-{
- unsigned long flags;
-
- head->func = func;
- local_irq_save(flags);
- __call_rcu(head, &rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data));
- local_irq_restore(flags);
-}
-EXPORT_SYMBOL_GPL(call_rcu_bh);
-
-/*
- * Return the number of RCU batches processed thus far. Useful
- * for debug and statistics.
- */
-long rcu_batches_completed(void)
-{
- return rcu_ctrlblk.completed;
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed);
-
-/*
- * Return the number of RCU batches processed thus far. Useful
- * for debug and statistics.
- */
-long rcu_batches_completed_bh(void)
-{
- return rcu_bh_ctrlblk.completed;
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
-
-/* Raises the softirq for processing rcu_callbacks. */
-static inline void raise_rcu_softirq(void)
-{
- raise_softirq(RCU_SOFTIRQ);
-}
-
-/*
- * Invoke the completed RCU callbacks. They are expected to be in
- * a per-cpu list.
- */
-static void rcu_do_batch(struct rcu_data *rdp)
-{
- unsigned long flags;
- struct rcu_head *next, *list;
- int count = 0;
-
- list = rdp->donelist;
- while (list) {
- next = list->next;
- prefetch(next);
- list->func(list);
- list = next;
- if (++count >= rdp->blimit)
- break;
- }
- rdp->donelist = list;
-
- local_irq_save(flags);
- rdp->qlen -= count;
- local_irq_restore(flags);
- if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark)
- rdp->blimit = blimit;
-
- if (!rdp->donelist)
- rdp->donetail = &rdp->donelist;
- else
- raise_rcu_softirq();
-}
-
-/*
- * Grace period handling:
- * The grace period handling consists out of two steps:
- * - A new grace period is started.
- * This is done by rcu_start_batch. The start is not broadcasted to
- * all cpus, they must pick this up by comparing rcp->cur with
- * rdp->quiescbatch. All cpus are recorded in the
- * rcu_ctrlblk.cpumask bitmap.
- * - All cpus must go through a quiescent state.
- * Since the start of the grace period is not broadcasted, at least two
- * calls to rcu_check_quiescent_state are required:
- * The first call just notices that a new grace period is running. The
- * following calls check if there was a quiescent state since the beginning
- * of the grace period. If so, it updates rcu_ctrlblk.cpumask. If
- * the bitmap is empty, then the grace period is completed.
- * rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace
- * period (if necessary).
- */
-
-/*
- * Register a new batch of callbacks, and start it up if there is currently no
- * active batch and the batch to be registered has not already occurred.
- * Caller must hold rcu_ctrlblk.lock.
- */
-static void rcu_start_batch(struct rcu_ctrlblk *rcp)
-{
- if (rcp->cur != rcp->pending &&
- rcp->completed == rcp->cur) {
- rcp->cur++;
- record_gp_stall_check_time(rcp);
-
- /*
- * Accessing nohz_cpu_mask before incrementing rcp->cur needs a
- * Barrier Otherwise it can cause tickless idle CPUs to be
- * included in rcp->cpumask, which will extend graceperiods
- * unnecessarily.
- */
- smp_mb();
- cpumask_andnot(to_cpumask(rcp->cpumask),
- cpu_online_mask, nohz_cpu_mask);
-
- rcp->signaled = 0;
- }
-}
-
-/*
- * cpu went through a quiescent state since the beginning of the grace period.
- * Clear it from the cpu mask and complete the grace period if it was the last
- * cpu. Start another grace period if someone has further entries pending
- */
-static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp)
-{
- cpumask_clear_cpu(cpu, to_cpumask(rcp->cpumask));
- if (cpumask_empty(to_cpumask(rcp->cpumask))) {
- /* batch completed ! */
- rcp->completed = rcp->cur;
- rcu_start_batch(rcp);
- }
-}
-
-/*
- * Check if the cpu has gone through a quiescent state (say context
- * switch). If so and if it already hasn't done so in this RCU
- * quiescent cycle, then indicate that it has done so.
- */
-static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp,
- struct rcu_data *rdp)
-{
- unsigned long flags;
-
- if (rdp->quiescbatch != rcp->cur) {
- /* start new grace period: */
- rdp->qs_pending = 1;
- rdp->passed_quiesc = 0;
- rdp->quiescbatch = rcp->cur;
- return;
- }
-
- /* Grace period already completed for this cpu?
- * qs_pending is checked instead of the actual bitmap to avoid
- * cacheline trashing.
- */
- if (!rdp->qs_pending)
- return;
-
- /*
- * Was there a quiescent state since the beginning of the grace
- * period? If no, then exit and wait for the next call.
- */
- if (!rdp->passed_quiesc)
- return;
- rdp->qs_pending = 0;
-
- spin_lock_irqsave(&rcp->lock, flags);
- /*
- * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync
- * during cpu startup. Ignore the quiescent state.
- */
- if (likely(rdp->quiescbatch == rcp->cur))
- cpu_quiet(rdp->cpu, rcp);
-
- spin_unlock_irqrestore(&rcp->lock, flags);
-}
-
-
-#ifdef CONFIG_HOTPLUG_CPU
-
-/* warning! helper for rcu_offline_cpu. do not use elsewhere without reviewing
- * locking requirements, the list it's pulling from has to belong to a cpu
- * which is dead and hence not processing interrupts.
- */
-static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list,
- struct rcu_head **tail, long batch)
-{
- unsigned long flags;
-
- if (list) {
- local_irq_save(flags);
- this_rdp->batch = batch;
- *this_rdp->nxttail[2] = list;
- this_rdp->nxttail[2] = tail;
- local_irq_restore(flags);
- }
-}
-
-static void __rcu_offline_cpu(struct rcu_data *this_rdp,
- struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
-{
- unsigned long flags;
-
- /*
- * if the cpu going offline owns the grace period
- * we can block indefinitely waiting for it, so flush
- * it here
- */
- spin_lock_irqsave(&rcp->lock, flags);
- if (rcp->cur != rcp->completed)
- cpu_quiet(rdp->cpu, rcp);
- rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail, rcp->cur + 1);
- rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail[2], rcp->cur + 1);
- spin_unlock(&rcp->lock);
-
- this_rdp->qlen += rdp->qlen;
- local_irq_restore(flags);
-}
-
-static void rcu_offline_cpu(int cpu)
-{
- struct rcu_data *this_rdp = &get_cpu_var(rcu_data);
- struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data);
-
- __rcu_offline_cpu(this_rdp, &rcu_ctrlblk,
- &per_cpu(rcu_data, cpu));
- __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk,
- &per_cpu(rcu_bh_data, cpu));
- put_cpu_var(rcu_data);
- put_cpu_var(rcu_bh_data);
-}
-
-#else
-
-static void rcu_offline_cpu(int cpu)
-{
-}
-
-#endif
-
-/*
- * This does the RCU processing work from softirq context.
- */
-static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
- struct rcu_data *rdp)
-{
- unsigned long flags;
- long completed_snap;
-
- if (rdp->nxtlist) {
- local_irq_save(flags);
- completed_snap = ACCESS_ONCE(rcp->completed);
-
- /*
- * move the other grace-period-completed entries to
- * [rdp->nxtlist, *rdp->nxttail[0]) temporarily
- */
- if (!rcu_batch_before(completed_snap, rdp->batch))
- rdp->nxttail[0] = rdp->nxttail[1] = rdp->nxttail[2];
- else if (!rcu_batch_before(completed_snap, rdp->batch - 1))
- rdp->nxttail[0] = rdp->nxttail[1];
-
- /*
- * the grace period for entries in
- * [rdp->nxtlist, *rdp->nxttail[0]) has completed and
- * move these entries to donelist
- */
- if (rdp->nxttail[0] != &rdp->nxtlist) {
- *rdp->donetail = rdp->nxtlist;
- rdp->donetail = rdp->nxttail[0];
- rdp->nxtlist = *rdp->nxttail[0];
- *rdp->donetail = NULL;
-
- if (rdp->nxttail[1] == rdp->nxttail[0])
- rdp->nxttail[1] = &rdp->nxtlist;
- if (rdp->nxttail[2] == rdp->nxttail[0])
- rdp->nxttail[2] = &rdp->nxtlist;
- rdp->nxttail[0] = &rdp->nxtlist;
- }
-
- local_irq_restore(flags);
-
- if (rcu_batch_after(rdp->batch, rcp->pending)) {
- unsigned long flags2;
-
- /* and start it/schedule start if it's a new batch */
- spin_lock_irqsave(&rcp->lock, flags2);
- if (rcu_batch_after(rdp->batch, rcp->pending)) {
- rcp->pending = rdp->batch;
- rcu_start_batch(rcp);
- }
- spin_unlock_irqrestore(&rcp->lock, flags2);
- }
- }
-
- rcu_check_quiescent_state(rcp, rdp);
- if (rdp->donelist)
- rcu_do_batch(rdp);
-}
-
-static void rcu_process_callbacks(struct softirq_action *unused)
-{
- /*
- * Memory references from any prior RCU read-side critical sections
- * executed by the interrupted code must be see before any RCU
- * grace-period manupulations below.
- */
-
- smp_mb(); /* See above block comment. */
-
- __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data));
- __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data));
-
- /*
- * Memory references from any later RCU read-side critical sections
- * executed by the interrupted code must be see after any RCU
- * grace-period manupulations above.
- */
-
- smp_mb(); /* See above block comment. */
-}
-
-static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
-{
- /* Check for CPU stalls, if enabled. */
- check_cpu_stall(rcp);
-
- if (rdp->nxtlist) {
- long completed_snap = ACCESS_ONCE(rcp->completed);
-
- /*
- * This cpu has pending rcu entries and the grace period
- * for them has completed.
- */
- if (!rcu_batch_before(completed_snap, rdp->batch))
- return 1;
- if (!rcu_batch_before(completed_snap, rdp->batch - 1) &&
- rdp->nxttail[0] != rdp->nxttail[1])
- return 1;
- if (rdp->nxttail[0] != &rdp->nxtlist)
- return 1;
-
- /*
- * This cpu has pending rcu entries and the new batch
- * for then hasn't been started nor scheduled start
- */
- if (rcu_batch_after(rdp->batch, rcp->pending))
- return 1;
- }
-
- /* This cpu has finished callbacks to invoke */
- if (rdp->donelist)
- return 1;
-
- /* The rcu core waits for a quiescent state from the cpu */
- if (rdp->quiescbatch != rcp->cur || rdp->qs_pending)
- return 1;
-
- /* nothing to do */
- return 0;
-}
-
-/*
- * Check to see if there is any immediate RCU-related work to be done
- * by the current CPU, returning 1 if so. This function is part of the
- * RCU implementation; it is -not- an exported member of the RCU API.
- */
-int rcu_pending(int cpu)
-{
- return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) ||
- __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
-}
-
-/*
- * Check to see if any future RCU-related work will need to be done
- * by the current CPU, even if none need be done immediately, returning
- * 1 if so. This function is part of the RCU implementation; it is -not-
- * an exported member of the RCU API.
- */
-int rcu_needs_cpu(int cpu)
-{
- struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
- struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu);
-
- return !!rdp->nxtlist || !!rdp_bh->nxtlist || rcu_pending(cpu);
-}
-
-/*
- * Top-level function driving RCU grace-period detection, normally
- * invoked from the scheduler-clock interrupt. This function simply
- * increments counters that are read only from softirq by this same
- * CPU, so there are no memory barriers required.
- */
-void rcu_check_callbacks(int cpu, int user)
-{
- if (user ||
- (idle_cpu(cpu) && rcu_scheduler_active &&
- !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
-
- /*
- * Get here if this CPU took its interrupt from user
- * mode or from the idle loop, and if this is not a
- * nested interrupt. In this case, the CPU is in
- * a quiescent state, so count it.
- *
- * Also do a memory barrier. This is needed to handle
- * the case where writes from a preempt-disable section
- * of code get reordered into schedule() by this CPU's
- * write buffer. The memory barrier makes sure that
- * the rcu_qsctr_inc() and rcu_bh_qsctr_inc() are see
- * by other CPUs to happen after any such write.
- */
-
- smp_mb(); /* See above block comment. */
- rcu_qsctr_inc(cpu);
- rcu_bh_qsctr_inc(cpu);
-
- } else if (!in_softirq()) {
-
- /*
- * Get here if this CPU did not take its interrupt from
- * softirq, in other words, if it is not interrupting
- * a rcu_bh read-side critical section. This is an _bh
- * critical section, so count it. The memory barrier
- * is needed for the same reason as is the above one.
- */
-
- smp_mb(); /* See above block comment. */
- rcu_bh_qsctr_inc(cpu);
- }
- raise_rcu_softirq();
-}
-
-static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp,
- struct rcu_data *rdp)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&rcp->lock, flags);
- memset(rdp, 0, sizeof(*rdp));
- rdp->nxttail[0] = rdp->nxttail[1] = rdp->nxttail[2] = &rdp->nxtlist;
- rdp->donetail = &rdp->donelist;
- rdp->quiescbatch = rcp->completed;
- rdp->qs_pending = 0;
- rdp->cpu = cpu;
- rdp->blimit = blimit;
- spin_unlock_irqrestore(&rcp->lock, flags);
-}
-
-static void __cpuinit rcu_online_cpu(int cpu)
-{
- struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
- struct rcu_data *bh_rdp = &per_cpu(rcu_bh_data, cpu);
-
- rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp);
- rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp);
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
-}
-
-static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
-{
- long cpu = (long)hcpu;
-
- switch (action) {
- case CPU_UP_PREPARE:
- case CPU_UP_PREPARE_FROZEN:
- rcu_online_cpu(cpu);
- break;
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- rcu_offline_cpu(cpu);
- break;
- default:
- break;
- }
- return NOTIFY_OK;
-}
-
-static struct notifier_block __cpuinitdata rcu_nb = {
- .notifier_call = rcu_cpu_notify,
-};
-
-/*
- * Initializes rcu mechanism. Assumed to be called early.
- * That is before local timer(SMP) or jiffie timer (uniproc) is setup.
- * Note that rcu_qsctr and friends are implicitly
- * initialized due to the choice of ``0'' for RCU_CTR_INVALID.
- */
-void __init __rcu_init(void)
-{
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
- printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
- rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE,
- (void *)(long)smp_processor_id());
- /* Register notifier for non-boot CPUs */
- register_cpu_notifier(&rcu_nb);
-}
-
-module_param(blimit, int, 0);
-module_param(qhimark, int, 0);
-module_param(qlowmark, int, 0);
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index a967c9feb90a..bd5d5c8e5140 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -98,6 +98,30 @@ void synchronize_rcu(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu);
+/**
+ * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
+ *
+ * Control will return to the caller some time after a full rcu_bh grace
+ * period has elapsed, in other words after all currently executing rcu_bh
+ * read-side critical sections have completed. RCU read-side critical
+ * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
+ * and may be nested.
+ */
+void synchronize_rcu_bh(void)
+{
+ struct rcu_synchronize rcu;
+
+ if (rcu_blocking_is_gp())
+ return;
+
+ init_completion(&rcu.completion);
+ /* Will wake me after RCU finished. */
+ call_rcu_bh(&rcu.head, wakeme_after_rcu);
+ /* Wait for it. */
+ wait_for_completion(&rcu.completion);
+}
+EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
+
static void rcu_barrier_callback(struct rcu_head *notused)
{
if (atomic_dec_and_test(&rcu_barrier_cpu_count))
@@ -129,6 +153,7 @@ static void rcu_barrier_func(void *type)
static inline void wait_migrated_callbacks(void)
{
wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count));
+ smp_mb(); /* In case we didn't sleep. */
}
/*
@@ -192,9 +217,13 @@ static void rcu_migrate_callback(struct rcu_head *notused)
wake_up(&rcu_migrate_wq);
}
+extern int rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu);
+
static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
unsigned long action, void *hcpu)
{
+ rcu_cpu_notify(self, action, hcpu);
if (action == CPU_DYING) {
/*
* preempt_disable() in on_each_cpu() prevents stop_machine(),
@@ -209,7 +238,8 @@ static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
call_rcu_bh(rcu_migrate_head, rcu_migrate_callback);
call_rcu_sched(rcu_migrate_head + 1, rcu_migrate_callback);
call_rcu(rcu_migrate_head + 2, rcu_migrate_callback);
- } else if (action == CPU_POST_DEAD) {
+ } else if (action == CPU_DOWN_PREPARE) {
+ /* Don't need to wait until next removal operation. */
/* rcu_migrate_head is protected by cpu_add_remove_lock */
wait_migrated_callbacks();
}
@@ -219,8 +249,18 @@ static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
void __init rcu_init(void)
{
+ int i;
+
__rcu_init();
- hotcpu_notifier(rcu_barrier_cpu_hotplug, 0);
+ cpu_notifier(rcu_barrier_cpu_hotplug, 0);
+
+ /*
+ * We don't need protection against CPU-hotplug here because
+ * this is called early in boot, before either interrupts
+ * or the scheduler are operational.
+ */
+ for_each_online_cpu(i)
+ rcu_barrier_cpu_hotplug(NULL, CPU_UP_PREPARE, (void *)(long)i);
}
void rcu_scheduler_starting(void)
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
deleted file mode 100644
index beb0e659adcc..000000000000
--- a/kernel/rcupreempt.c
+++ /dev/null
@@ -1,1539 +0,0 @@
-/*
- * Read-Copy Update mechanism for mutual exclusion, realtime implementation
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright IBM Corporation, 2006
- *
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
- * With thanks to Esben Nielsen, Bill Huey, and Ingo Molnar
- * for pushing me away from locks and towards counters, and
- * to Suparna Bhattacharya for pushing me completely away
- * from atomic instructions on the read side.
- *
- * - Added handling of Dynamic Ticks
- * Copyright 2007 - Paul E. Mckenney <paulmck@us.ibm.com>
- * - Steven Rostedt <srostedt@redhat.com>
- *
- * Papers: http://www.rdrop.com/users/paulmck/RCU
- *
- * Design Document: http://lwn.net/Articles/253651/
- *
- * For detailed explanation of Read-Copy Update mechanism see -
- * Documentation/RCU/ *.txt
- *
- */
-#include <linux/types.h>
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/spinlock.h>
-#include <linux/smp.h>
-#include <linux/rcupdate.h>
-#include <linux/interrupt.h>
-#include <linux/sched.h>
-#include <asm/atomic.h>
-#include <linux/bitops.h>
-#include <linux/module.h>
-#include <linux/kthread.h>
-#include <linux/completion.h>
-#include <linux/moduleparam.h>
-#include <linux/percpu.h>
-#include <linux/notifier.h>
-#include <linux/cpu.h>
-#include <linux/random.h>
-#include <linux/delay.h>
-#include <linux/cpumask.h>
-#include <linux/rcupreempt_trace.h>
-#include <asm/byteorder.h>
-
-/*
- * PREEMPT_RCU data structures.
- */
-
-/*
- * GP_STAGES specifies the number of times the state machine has
- * to go through the all the rcu_try_flip_states (see below)
- * in a single Grace Period.
- *
- * GP in GP_STAGES stands for Grace Period ;)
- */
-#define GP_STAGES 2
-struct rcu_data {
- spinlock_t lock; /* Protect rcu_data fields. */
- long completed; /* Number of last completed batch. */
- int waitlistcount;
- struct rcu_head *nextlist;
- struct rcu_head **nexttail;
- struct rcu_head *waitlist[GP_STAGES];
- struct rcu_head **waittail[GP_STAGES];
- struct rcu_head *donelist; /* from waitlist & waitschedlist */
- struct rcu_head **donetail;
- long rcu_flipctr[2];
- struct rcu_head *nextschedlist;
- struct rcu_head **nextschedtail;
- struct rcu_head *waitschedlist;
- struct rcu_head **waitschedtail;
- int rcu_sched_sleeping;
-#ifdef CONFIG_RCU_TRACE
- struct rcupreempt_trace trace;
-#endif /* #ifdef CONFIG_RCU_TRACE */
-};
-
-/*
- * States for rcu_try_flip() and friends.
- */
-
-enum rcu_try_flip_states {
-
- /*
- * Stay here if nothing is happening. Flip the counter if somthing
- * starts happening. Denoted by "I"
- */
- rcu_try_flip_idle_state,
-
- /*
- * Wait here for all CPUs to notice that the counter has flipped. This
- * prevents the old set of counters from ever being incremented once
- * we leave this state, which in turn is necessary because we cannot
- * test any individual counter for zero -- we can only check the sum.
- * Denoted by "A".
- */
- rcu_try_flip_waitack_state,
-
- /*
- * Wait here for the sum of the old per-CPU counters to reach zero.
- * Denoted by "Z".
- */
- rcu_try_flip_waitzero_state,
-
- /*
- * Wait here for each of the other CPUs to execute a memory barrier.
- * This is necessary to ensure that these other CPUs really have
- * completed executing their RCU read-side critical sections, despite
- * their CPUs wildly reordering memory. Denoted by "M".
- */
- rcu_try_flip_waitmb_state,
-};
-
-/*
- * States for rcu_ctrlblk.rcu_sched_sleep.
- */
-
-enum rcu_sched_sleep_states {
- rcu_sched_not_sleeping, /* Not sleeping, callbacks need GP. */
- rcu_sched_sleep_prep, /* Thinking of sleeping, rechecking. */
- rcu_sched_sleeping, /* Sleeping, awaken if GP needed. */
-};
-
-struct rcu_ctrlblk {
- spinlock_t fliplock; /* Protect state-machine transitions. */
- long completed; /* Number of last completed batch. */
- enum rcu_try_flip_states rcu_try_flip_state; /* The current state of
- the rcu state machine */
- spinlock_t schedlock; /* Protect rcu_sched sleep state. */
- enum rcu_sched_sleep_states sched_sleep; /* rcu_sched state. */
- wait_queue_head_t sched_wq; /* Place for rcu_sched to sleep. */
-};
-
-struct rcu_dyntick_sched {
- int dynticks;
- int dynticks_snap;
- int sched_qs;
- int sched_qs_snap;
- int sched_dynticks_snap;
-};
-
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_dyntick_sched, rcu_dyntick_sched) = {
- .dynticks = 1,
-};
-
-void rcu_qsctr_inc(int cpu)
-{
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- rdssp->sched_qs++;
-}
-
-#ifdef CONFIG_NO_HZ
-
-void rcu_enter_nohz(void)
-{
- static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
-
- smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
- __get_cpu_var(rcu_dyntick_sched).dynticks++;
- WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs);
-}
-
-void rcu_exit_nohz(void)
-{
- static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
-
- __get_cpu_var(rcu_dyntick_sched).dynticks++;
- smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
- WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
- &rs);
-}
-
-#endif /* CONFIG_NO_HZ */
-
-
-static DEFINE_PER_CPU(struct rcu_data, rcu_data);
-
-static struct rcu_ctrlblk rcu_ctrlblk = {
- .fliplock = __SPIN_LOCK_UNLOCKED(rcu_ctrlblk.fliplock),
- .completed = 0,
- .rcu_try_flip_state = rcu_try_flip_idle_state,
- .schedlock = __SPIN_LOCK_UNLOCKED(rcu_ctrlblk.schedlock),
- .sched_sleep = rcu_sched_not_sleeping,
- .sched_wq = __WAIT_QUEUE_HEAD_INITIALIZER(rcu_ctrlblk.sched_wq),
-};
-
-static struct task_struct *rcu_sched_grace_period_task;
-
-#ifdef CONFIG_RCU_TRACE
-static char *rcu_try_flip_state_names[] =
- { "idle", "waitack", "waitzero", "waitmb" };
-#endif /* #ifdef CONFIG_RCU_TRACE */
-
-static DECLARE_BITMAP(rcu_cpu_online_map, NR_CPUS) __read_mostly
- = CPU_BITS_NONE;
-
-/*
- * Enum and per-CPU flag to determine when each CPU has seen
- * the most recent counter flip.
- */
-
-enum rcu_flip_flag_values {
- rcu_flip_seen, /* Steady/initial state, last flip seen. */
- /* Only GP detector can update. */
- rcu_flipped /* Flip just completed, need confirmation. */
- /* Only corresponding CPU can update. */
-};
-static DEFINE_PER_CPU_SHARED_ALIGNED(enum rcu_flip_flag_values, rcu_flip_flag)
- = rcu_flip_seen;
-
-/*
- * Enum and per-CPU flag to determine when each CPU has executed the
- * needed memory barrier to fence in memory references from its last RCU
- * read-side critical section in the just-completed grace period.
- */
-
-enum rcu_mb_flag_values {
- rcu_mb_done, /* Steady/initial state, no mb()s required. */
- /* Only GP detector can update. */
- rcu_mb_needed /* Flip just completed, need an mb(). */
- /* Only corresponding CPU can update. */
-};
-static DEFINE_PER_CPU_SHARED_ALIGNED(enum rcu_mb_flag_values, rcu_mb_flag)
- = rcu_mb_done;
-
-/*
- * RCU_DATA_ME: find the current CPU's rcu_data structure.
- * RCU_DATA_CPU: find the specified CPU's rcu_data structure.
- */
-#define RCU_DATA_ME() (&__get_cpu_var(rcu_data))
-#define RCU_DATA_CPU(cpu) (&per_cpu(rcu_data, cpu))
-
-/*
- * Helper macro for tracing when the appropriate rcu_data is not
- * cached in a local variable, but where the CPU number is so cached.
- */
-#define RCU_TRACE_CPU(f, cpu) RCU_TRACE(f, &(RCU_DATA_CPU(cpu)->trace));
-
-/*
- * Helper macro for tracing when the appropriate rcu_data is not
- * cached in a local variable.
- */
-#define RCU_TRACE_ME(f) RCU_TRACE(f, &(RCU_DATA_ME()->trace));
-
-/*
- * Helper macro for tracing when the appropriate rcu_data is pointed
- * to by a local variable.
- */
-#define RCU_TRACE_RDP(f, rdp) RCU_TRACE(f, &((rdp)->trace));
-
-#define RCU_SCHED_BATCH_TIME (HZ / 50)
-
-/*
- * Return the number of RCU batches processed thus far. Useful
- * for debug and statistics.
- */
-long rcu_batches_completed(void)
-{
- return rcu_ctrlblk.completed;
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed);
-
-void __rcu_read_lock(void)
-{
- int idx;
- struct task_struct *t = current;
- int nesting;
-
- nesting = ACCESS_ONCE(t->rcu_read_lock_nesting);
- if (nesting != 0) {
-
- /* An earlier rcu_read_lock() covers us, just count it. */
-
- t->rcu_read_lock_nesting = nesting + 1;
-
- } else {
- unsigned long flags;
-
- /*
- * We disable interrupts for the following reasons:
- * - If we get scheduling clock interrupt here, and we
- * end up acking the counter flip, it's like a promise
- * that we will never increment the old counter again.
- * Thus we will break that promise if that
- * scheduling clock interrupt happens between the time
- * we pick the .completed field and the time that we
- * increment our counter.
- *
- * - We don't want to be preempted out here.
- *
- * NMIs can still occur, of course, and might themselves
- * contain rcu_read_lock().
- */
-
- local_irq_save(flags);
-
- /*
- * Outermost nesting of rcu_read_lock(), so increment
- * the current counter for the current CPU. Use volatile
- * casts to prevent the compiler from reordering.
- */
-
- idx = ACCESS_ONCE(rcu_ctrlblk.completed) & 0x1;
- ACCESS_ONCE(RCU_DATA_ME()->rcu_flipctr[idx])++;
-
- /*
- * Now that the per-CPU counter has been incremented, we
- * are protected from races with rcu_read_lock() invoked
- * from NMI handlers on this CPU. We can therefore safely
- * increment the nesting counter, relieving further NMIs
- * of the need to increment the per-CPU counter.
- */
-
- ACCESS_ONCE(t->rcu_read_lock_nesting) = nesting + 1;
-
- /*
- * Now that we have preventing any NMIs from storing
- * to the ->rcu_flipctr_idx, we can safely use it to
- * remember which counter to decrement in the matching
- * rcu_read_unlock().
- */
-
- ACCESS_ONCE(t->rcu_flipctr_idx) = idx;
- local_irq_restore(flags);
- }
-}
-EXPORT_SYMBOL_GPL(__rcu_read_lock);
-
-void __rcu_read_unlock(void)
-{
- int idx;
- struct task_struct *t = current;
- int nesting;
-
- nesting = ACCESS_ONCE(t->rcu_read_lock_nesting);
- if (nesting > 1) {
-
- /*
- * We are still protected by the enclosing rcu_read_lock(),
- * so simply decrement the counter.
- */
-
- t->rcu_read_lock_nesting = nesting - 1;
-
- } else {
- unsigned long flags;
-
- /*
- * Disable local interrupts to prevent the grace-period
- * detection state machine from seeing us half-done.
- * NMIs can still occur, of course, and might themselves
- * contain rcu_read_lock() and rcu_read_unlock().
- */
-
- local_irq_save(flags);
-
- /*
- * Outermost nesting of rcu_read_unlock(), so we must
- * decrement the current counter for the current CPU.
- * This must be done carefully, because NMIs can
- * occur at any point in this code, and any rcu_read_lock()
- * and rcu_read_unlock() pairs in the NMI handlers
- * must interact non-destructively with this code.
- * Lots of volatile casts, and -very- careful ordering.
- *
- * Changes to this code, including this one, must be
- * inspected, validated, and tested extremely carefully!!!
- */
-
- /*
- * First, pick up the index.
- */
-
- idx = ACCESS_ONCE(t->rcu_flipctr_idx);
-
- /*
- * Now that we have fetched the counter index, it is
- * safe to decrement the per-task RCU nesting counter.
- * After this, any interrupts or NMIs will increment and
- * decrement the per-CPU counters.
- */
- ACCESS_ONCE(t->rcu_read_lock_nesting) = nesting - 1;
-
- /*
- * It is now safe to decrement this task's nesting count.
- * NMIs that occur after this statement will route their
- * rcu_read_lock() calls through this "else" clause, and
- * will thus start incrementing the per-CPU counter on
- * their own. They will also clobber ->rcu_flipctr_idx,
- * but that is OK, since we have already fetched it.
- */
-
- ACCESS_ONCE(RCU_DATA_ME()->rcu_flipctr[idx])--;
- local_irq_restore(flags);
- }
-}
-EXPORT_SYMBOL_GPL(__rcu_read_unlock);
-
-/*
- * If a global counter flip has occurred since the last time that we
- * advanced callbacks, advance them. Hardware interrupts must be
- * disabled when calling this function.
- */
-static void __rcu_advance_callbacks(struct rcu_data *rdp)
-{
- int cpu;
- int i;
- int wlc = 0;
-
- if (rdp->completed != rcu_ctrlblk.completed) {
- if (rdp->waitlist[GP_STAGES - 1] != NULL) {
- *rdp->donetail = rdp->waitlist[GP_STAGES - 1];
- rdp->donetail = rdp->waittail[GP_STAGES - 1];
- RCU_TRACE_RDP(rcupreempt_trace_move2done, rdp);
- }
- for (i = GP_STAGES - 2; i >= 0; i--) {
- if (rdp->waitlist[i] != NULL) {
- rdp->waitlist[i + 1] = rdp->waitlist[i];
- rdp->waittail[i + 1] = rdp->waittail[i];
- wlc++;
- } else {
- rdp->waitlist[i + 1] = NULL;
- rdp->waittail[i + 1] =
- &rdp->waitlist[i + 1];
- }
- }
- if (rdp->nextlist != NULL) {
- rdp->waitlist[0] = rdp->nextlist;
- rdp->waittail[0] = rdp->nexttail;
- wlc++;
- rdp->nextlist = NULL;
- rdp->nexttail = &rdp->nextlist;
- RCU_TRACE_RDP(rcupreempt_trace_move2wait, rdp);
- } else {
- rdp->waitlist[0] = NULL;
- rdp->waittail[0] = &rdp->waitlist[0];
- }
- rdp->waitlistcount = wlc;
- rdp->completed = rcu_ctrlblk.completed;
- }
-
- /*
- * Check to see if this CPU needs to report that it has seen
- * the most recent counter flip, thereby declaring that all
- * subsequent rcu_read_lock() invocations will respect this flip.
- */
-
- cpu = raw_smp_processor_id();
- if (per_cpu(rcu_flip_flag, cpu) == rcu_flipped) {
- smp_mb(); /* Subsequent counter accesses must see new value */
- per_cpu(rcu_flip_flag, cpu) = rcu_flip_seen;
- smp_mb(); /* Subsequent RCU read-side critical sections */
- /* seen -after- acknowledgement. */
- }
-}
-
-#ifdef CONFIG_NO_HZ
-static DEFINE_PER_CPU(int, rcu_update_flag);
-
-/**
- * rcu_irq_enter - Called from Hard irq handlers and NMI/SMI.
- *
- * If the CPU was idle with dynamic ticks active, this updates the
- * rcu_dyntick_sched.dynticks to let the RCU handling know that the
- * CPU is active.
- */
-void rcu_irq_enter(void)
-{
- int cpu = smp_processor_id();
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- if (per_cpu(rcu_update_flag, cpu))
- per_cpu(rcu_update_flag, cpu)++;
-
- /*
- * Only update if we are coming from a stopped ticks mode
- * (rcu_dyntick_sched.dynticks is even).
- */
- if (!in_interrupt() &&
- (rdssp->dynticks & 0x1) == 0) {
- /*
- * The following might seem like we could have a race
- * with NMI/SMIs. But this really isn't a problem.
- * Here we do a read/modify/write, and the race happens
- * when an NMI/SMI comes in after the read and before
- * the write. But NMI/SMIs will increment this counter
- * twice before returning, so the zero bit will not
- * be corrupted by the NMI/SMI which is the most important
- * part.
- *
- * The only thing is that we would bring back the counter
- * to a postion that it was in during the NMI/SMI.
- * But the zero bit would be set, so the rest of the
- * counter would again be ignored.
- *
- * On return from the IRQ, the counter may have the zero
- * bit be 0 and the counter the same as the return from
- * the NMI/SMI. If the state machine was so unlucky to
- * see that, it still doesn't matter, since all
- * RCU read-side critical sections on this CPU would
- * have already completed.
- */
- rdssp->dynticks++;
- /*
- * The following memory barrier ensures that any
- * rcu_read_lock() primitives in the irq handler
- * are seen by other CPUs to follow the above
- * increment to rcu_dyntick_sched.dynticks. This is
- * required in order for other CPUs to correctly
- * determine when it is safe to advance the RCU
- * grace-period state machine.
- */
- smp_mb(); /* see above block comment. */
- /*
- * Since we can't determine the dynamic tick mode from
- * the rcu_dyntick_sched.dynticks after this routine,
- * we use a second flag to acknowledge that we came
- * from an idle state with ticks stopped.
- */
- per_cpu(rcu_update_flag, cpu)++;
- /*
- * If we take an NMI/SMI now, they will also increment
- * the rcu_update_flag, and will not update the
- * rcu_dyntick_sched.dynticks on exit. That is for
- * this IRQ to do.
- */
- }
-}
-
-/**
- * rcu_irq_exit - Called from exiting Hard irq context.
- *
- * If the CPU was idle with dynamic ticks active, update the
- * rcu_dyntick_sched.dynticks to put let the RCU handling be
- * aware that the CPU is going back to idle with no ticks.
- */
-void rcu_irq_exit(void)
-{
- int cpu = smp_processor_id();
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- /*
- * rcu_update_flag is set if we interrupted the CPU
- * when it was idle with ticks stopped.
- * Once this occurs, we keep track of interrupt nesting
- * because a NMI/SMI could also come in, and we still
- * only want the IRQ that started the increment of the
- * rcu_dyntick_sched.dynticks to be the one that modifies
- * it on exit.
- */
- if (per_cpu(rcu_update_flag, cpu)) {
- if (--per_cpu(rcu_update_flag, cpu))
- return;
-
- /* This must match the interrupt nesting */
- WARN_ON(in_interrupt());
-
- /*
- * If an NMI/SMI happens now we are still
- * protected by the rcu_dyntick_sched.dynticks being odd.
- */
-
- /*
- * The following memory barrier ensures that any
- * rcu_read_unlock() primitives in the irq handler
- * are seen by other CPUs to preceed the following
- * increment to rcu_dyntick_sched.dynticks. This
- * is required in order for other CPUs to determine
- * when it is safe to advance the RCU grace-period
- * state machine.
- */
- smp_mb(); /* see above block comment. */
- rdssp->dynticks++;
- WARN_ON(rdssp->dynticks & 0x1);
- }
-}
-
-void rcu_nmi_enter(void)
-{
- rcu_irq_enter();
-}
-
-void rcu_nmi_exit(void)
-{
- rcu_irq_exit();
-}
-
-static void dyntick_save_progress_counter(int cpu)
-{
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- rdssp->dynticks_snap = rdssp->dynticks;
-}
-
-static inline int
-rcu_try_flip_waitack_needed(int cpu)
-{
- long curr;
- long snap;
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- curr = rdssp->dynticks;
- snap = rdssp->dynticks_snap;
- smp_mb(); /* force ordering with cpu entering/leaving dynticks. */
-
- /*
- * If the CPU remained in dynticks mode for the entire time
- * and didn't take any interrupts, NMIs, SMIs, or whatever,
- * then it cannot be in the middle of an rcu_read_lock(), so
- * the next rcu_read_lock() it executes must use the new value
- * of the counter. So we can safely pretend that this CPU
- * already acknowledged the counter.
- */
-
- if ((curr == snap) && ((curr & 0x1) == 0))
- return 0;
-
- /*
- * If the CPU passed through or entered a dynticks idle phase with
- * no active irq handlers, then, as above, we can safely pretend
- * that this CPU already acknowledged the counter.
- */
-
- if ((curr - snap) > 2 || (curr & 0x1) == 0)
- return 0;
-
- /* We need this CPU to explicitly acknowledge the counter flip. */
-
- return 1;
-}
-
-static inline int
-rcu_try_flip_waitmb_needed(int cpu)
-{
- long curr;
- long snap;
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- curr = rdssp->dynticks;
- snap = rdssp->dynticks_snap;
- smp_mb(); /* force ordering with cpu entering/leaving dynticks. */
-
- /*
- * If the CPU remained in dynticks mode for the entire time
- * and didn't take any interrupts, NMIs, SMIs, or whatever,
- * then it cannot have executed an RCU read-side critical section
- * during that time, so there is no need for it to execute a
- * memory barrier.
- */
-
- if ((curr == snap) && ((curr & 0x1) == 0))
- return 0;
-
- /*
- * If the CPU either entered or exited an outermost interrupt,
- * SMI, NMI, or whatever handler, then we know that it executed
- * a memory barrier when doing so. So we don't need another one.
- */
- if (curr != snap)
- return 0;
-
- /* We need the CPU to execute a memory barrier. */
-
- return 1;
-}
-
-static void dyntick_save_progress_counter_sched(int cpu)
-{
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- rdssp->sched_dynticks_snap = rdssp->dynticks;
-}
-
-static int rcu_qsctr_inc_needed_dyntick(int cpu)
-{
- long curr;
- long snap;
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- curr = rdssp->dynticks;
- snap = rdssp->sched_dynticks_snap;
- smp_mb(); /* force ordering with cpu entering/leaving dynticks. */
-
- /*
- * If the CPU remained in dynticks mode for the entire time
- * and didn't take any interrupts, NMIs, SMIs, or whatever,
- * then it cannot be in the middle of an rcu_read_lock(), so
- * the next rcu_read_lock() it executes must use the new value
- * of the counter. Therefore, this CPU has been in a quiescent
- * state the entire time, and we don't need to wait for it.
- */
-
- if ((curr == snap) && ((curr & 0x1) == 0))
- return 0;
-
- /*
- * If the CPU passed through or entered a dynticks idle phase with
- * no active irq handlers, then, as above, this CPU has already
- * passed through a quiescent state.
- */
-
- if ((curr - snap) > 2 || (snap & 0x1) == 0)
- return 0;
-
- /* We need this CPU to go through a quiescent state. */
-
- return 1;
-}
-
-#else /* !CONFIG_NO_HZ */
-
-# define dyntick_save_progress_counter(cpu) do { } while (0)
-# define rcu_try_flip_waitack_needed(cpu) (1)
-# define rcu_try_flip_waitmb_needed(cpu) (1)
-
-# define dyntick_save_progress_counter_sched(cpu) do { } while (0)
-# define rcu_qsctr_inc_needed_dyntick(cpu) (1)
-
-#endif /* CONFIG_NO_HZ */
-
-static void save_qsctr_sched(int cpu)
-{
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- rdssp->sched_qs_snap = rdssp->sched_qs;
-}
-
-static inline int rcu_qsctr_inc_needed(int cpu)
-{
- struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
-
- /*
- * If there has been a quiescent state, no more need to wait
- * on this CPU.
- */
-
- if (rdssp->sched_qs != rdssp->sched_qs_snap) {
- smp_mb(); /* force ordering with cpu entering schedule(). */
- return 0;
- }
-
- /* We need this CPU to go through a quiescent state. */
-
- return 1;
-}
-
-/*
- * Get here when RCU is idle. Decide whether we need to
- * move out of idle state, and return non-zero if so.
- * "Straightforward" approach for the moment, might later
- * use callback-list lengths, grace-period duration, or
- * some such to determine when to exit idle state.
- * Might also need a pre-idle test that does not acquire
- * the lock, but let's get the simple case working first...
- */
-
-static int
-rcu_try_flip_idle(void)
-{
- int cpu;
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_i1);
- if (!rcu_pending(smp_processor_id())) {
- RCU_TRACE_ME(rcupreempt_trace_try_flip_ie1);
- return 0;
- }
-
- /*
- * Do the flip.
- */
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_g1);
- rcu_ctrlblk.completed++; /* stands in for rcu_try_flip_g2 */
-
- /*
- * Need a memory barrier so that other CPUs see the new
- * counter value before they see the subsequent change of all
- * the rcu_flip_flag instances to rcu_flipped.
- */
-
- smp_mb(); /* see above block comment. */
-
- /* Now ask each CPU for acknowledgement of the flip. */
-
- for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) {
- per_cpu(rcu_flip_flag, cpu) = rcu_flipped;
- dyntick_save_progress_counter(cpu);
- }
-
- return 1;
-}
-
-/*
- * Wait for CPUs to acknowledge the flip.
- */
-
-static int
-rcu_try_flip_waitack(void)
-{
- int cpu;
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_a1);
- for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map))
- if (rcu_try_flip_waitack_needed(cpu) &&
- per_cpu(rcu_flip_flag, cpu) != rcu_flip_seen) {
- RCU_TRACE_ME(rcupreempt_trace_try_flip_ae1);
- return 0;
- }
-
- /*
- * Make sure our checks above don't bleed into subsequent
- * waiting for the sum of the counters to reach zero.
- */
-
- smp_mb(); /* see above block comment. */
- RCU_TRACE_ME(rcupreempt_trace_try_flip_a2);
- return 1;
-}
-
-/*
- * Wait for collective ``last'' counter to reach zero,
- * then tell all CPUs to do an end-of-grace-period memory barrier.
- */
-
-static int
-rcu_try_flip_waitzero(void)
-{
- int cpu;
- int lastidx = !(rcu_ctrlblk.completed & 0x1);
- int sum = 0;
-
- /* Check to see if the sum of the "last" counters is zero. */
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_z1);
- for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map))
- sum += RCU_DATA_CPU(cpu)->rcu_flipctr[lastidx];
- if (sum != 0) {
- RCU_TRACE_ME(rcupreempt_trace_try_flip_ze1);
- return 0;
- }
-
- /*
- * This ensures that the other CPUs see the call for
- * memory barriers -after- the sum to zero has been
- * detected here
- */
- smp_mb(); /* ^^^^^^^^^^^^ */
-
- /* Call for a memory barrier from each CPU. */
- for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map)) {
- per_cpu(rcu_mb_flag, cpu) = rcu_mb_needed;
- dyntick_save_progress_counter(cpu);
- }
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_z2);
- return 1;
-}
-
-/*
- * Wait for all CPUs to do their end-of-grace-period memory barrier.
- * Return 0 once all CPUs have done so.
- */
-
-static int
-rcu_try_flip_waitmb(void)
-{
- int cpu;
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_m1);
- for_each_cpu(cpu, to_cpumask(rcu_cpu_online_map))
- if (rcu_try_flip_waitmb_needed(cpu) &&
- per_cpu(rcu_mb_flag, cpu) != rcu_mb_done) {
- RCU_TRACE_ME(rcupreempt_trace_try_flip_me1);
- return 0;
- }
-
- smp_mb(); /* Ensure that the above checks precede any following flip. */
- RCU_TRACE_ME(rcupreempt_trace_try_flip_m2);
- return 1;
-}
-
-/*
- * Attempt a single flip of the counters. Remember, a single flip does
- * -not- constitute a grace period. Instead, the interval between
- * at least GP_STAGES consecutive flips is a grace period.
- *
- * If anyone is nuts enough to run this CONFIG_PREEMPT_RCU implementation
- * on a large SMP, they might want to use a hierarchical organization of
- * the per-CPU-counter pairs.
- */
-static void rcu_try_flip(void)
-{
- unsigned long flags;
-
- RCU_TRACE_ME(rcupreempt_trace_try_flip_1);
- if (unlikely(!spin_trylock_irqsave(&rcu_ctrlblk.fliplock, flags))) {
- RCU_TRACE_ME(rcupreempt_trace_try_flip_e1);
- return;
- }
-
- /*
- * Take the next transition(s) through the RCU grace-period
- * flip-counter state machine.
- */
-
- switch (rcu_ctrlblk.rcu_try_flip_state) {
- case rcu_try_flip_idle_state:
- if (rcu_try_flip_idle())
- rcu_ctrlblk.rcu_try_flip_state =
- rcu_try_flip_waitack_state;
- break;
- case rcu_try_flip_waitack_state:
- if (rcu_try_flip_waitack())
- rcu_ctrlblk.rcu_try_flip_state =
- rcu_try_flip_waitzero_state;
- break;
- case rcu_try_flip_waitzero_state:
- if (rcu_try_flip_waitzero())
- rcu_ctrlblk.rcu_try_flip_state =
- rcu_try_flip_waitmb_state;
- break;
- case rcu_try_flip_waitmb_state:
- if (rcu_try_flip_waitmb())
- rcu_ctrlblk.rcu_try_flip_state =
- rcu_try_flip_idle_state;
- }
- spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags);
-}
-
-/*
- * Check to see if this CPU needs to do a memory barrier in order to
- * ensure that any prior RCU read-side critical sections have committed
- * their counter manipulations and critical-section memory references
- * before declaring the grace period to be completed.
- */
-static void rcu_check_mb(int cpu)
-{
- if (per_cpu(rcu_mb_flag, cpu) == rcu_mb_needed) {
- smp_mb(); /* Ensure RCU read-side accesses are visible. */
- per_cpu(rcu_mb_flag, cpu) = rcu_mb_done;
- }
-}
-
-void rcu_check_callbacks(int cpu, int user)
-{
- unsigned long flags;
- struct rcu_data *rdp = RCU_DATA_CPU(cpu);
-
- /*
- * If this CPU took its interrupt from user mode or from the
- * idle loop, and this is not a nested interrupt, then
- * this CPU has to have exited all prior preept-disable
- * sections of code. So increment the counter to note this.
- *
- * The memory barrier is needed to handle the case where
- * writes from a preempt-disable section of code get reordered
- * into schedule() by this CPU's write buffer. So the memory
- * barrier makes sure that the rcu_qsctr_inc() is seen by other
- * CPUs to happen after any such write.
- */
-
- if (user ||
- (idle_cpu(cpu) && !in_softirq() &&
- hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
- smp_mb(); /* Guard against aggressive schedule(). */
- rcu_qsctr_inc(cpu);
- }
-
- rcu_check_mb(cpu);
- if (rcu_ctrlblk.completed == rdp->completed)
- rcu_try_flip();
- spin_lock_irqsave(&rdp->lock, flags);
- RCU_TRACE_RDP(rcupreempt_trace_check_callbacks, rdp);
- __rcu_advance_callbacks(rdp);
- if (rdp->donelist == NULL) {
- spin_unlock_irqrestore(&rdp->lock, flags);
- } else {
- spin_unlock_irqrestore(&rdp->lock, flags);
- raise_softirq(RCU_SOFTIRQ);
- }
-}
-
-/*
- * Needed by dynticks, to make sure all RCU processing has finished
- * when we go idle:
- */
-void rcu_advance_callbacks(int cpu, int user)
-{
- unsigned long flags;
- struct rcu_data *rdp = RCU_DATA_CPU(cpu);
-
- if (rcu_ctrlblk.completed == rdp->completed) {
- rcu_try_flip();
- if (rcu_ctrlblk.completed == rdp->completed)
- return;
- }
- spin_lock_irqsave(&rdp->lock, flags);
- RCU_TRACE_RDP(rcupreempt_trace_check_callbacks, rdp);
- __rcu_advance_callbacks(rdp);
- spin_unlock_irqrestore(&rdp->lock, flags);
-}
-
-#ifdef CONFIG_HOTPLUG_CPU
-#define rcu_offline_cpu_enqueue(srclist, srctail, dstlist, dsttail) do { \
- *dsttail = srclist; \
- if (srclist != NULL) { \
- dsttail = srctail; \
- srclist = NULL; \
- srctail = &srclist;\
- } \
- } while (0)
-
-void rcu_offline_cpu(int cpu)
-{
- int i;
- struct rcu_head *list = NULL;
- unsigned long flags;
- struct rcu_data *rdp = RCU_DATA_CPU(cpu);
- struct rcu_head *schedlist = NULL;
- struct rcu_head **schedtail = &schedlist;
- struct rcu_head **tail = &list;
-
- /*
- * Remove all callbacks from the newly dead CPU, retaining order.
- * Otherwise rcu_barrier() will fail
- */
-
- spin_lock_irqsave(&rdp->lock, flags);
- rcu_offline_cpu_enqueue(rdp->donelist, rdp->donetail, list, tail);
- for (i = GP_STAGES - 1; i >= 0; i--)
- rcu_offline_cpu_enqueue(rdp->waitlist[i], rdp->waittail[i],
- list, tail);
- rcu_offline_cpu_enqueue(rdp->nextlist, rdp->nexttail, list, tail);
- rcu_offline_cpu_enqueue(rdp->waitschedlist, rdp->waitschedtail,
- schedlist, schedtail);
- rcu_offline_cpu_enqueue(rdp->nextschedlist, rdp->nextschedtail,
- schedlist, schedtail);
- rdp->rcu_sched_sleeping = 0;
- spin_unlock_irqrestore(&rdp->lock, flags);
- rdp->waitlistcount = 0;
-
- /* Disengage the newly dead CPU from the grace-period computation. */
-
- spin_lock_irqsave(&rcu_ctrlblk.fliplock, flags);
- rcu_check_mb(cpu);
- if (per_cpu(rcu_flip_flag, cpu) == rcu_flipped) {
- smp_mb(); /* Subsequent counter accesses must see new value */
- per_cpu(rcu_flip_flag, cpu) = rcu_flip_seen;
- smp_mb(); /* Subsequent RCU read-side critical sections */
- /* seen -after- acknowledgement. */
- }
-
- RCU_DATA_ME()->rcu_flipctr[0] += RCU_DATA_CPU(cpu)->rcu_flipctr[0];
- RCU_DATA_ME()->rcu_flipctr[1] += RCU_DATA_CPU(cpu)->rcu_flipctr[1];
-
- RCU_DATA_CPU(cpu)->rcu_flipctr[0] = 0;
- RCU_DATA_CPU(cpu)->rcu_flipctr[1] = 0;
-
- cpumask_clear_cpu(cpu, to_cpumask(rcu_cpu_online_map));
-
- spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags);
-
- /*
- * Place the removed callbacks on the current CPU's queue.
- * Make them all start a new grace period: simple approach,
- * in theory could starve a given set of callbacks, but
- * you would need to be doing some serious CPU hotplugging
- * to make this happen. If this becomes a problem, adding
- * a synchronize_rcu() to the hotplug path would be a simple
- * fix.
- */
-
- local_irq_save(flags); /* disable preempt till we know what lock. */
- rdp = RCU_DATA_ME();
- spin_lock(&rdp->lock);
- *rdp->nexttail = list;
- if (list)
- rdp->nexttail = tail;
- *rdp->nextschedtail = schedlist;
- if (schedlist)
- rdp->nextschedtail = schedtail;
- spin_unlock_irqrestore(&rdp->lock, flags);
-}
-
-#else /* #ifdef CONFIG_HOTPLUG_CPU */
-
-void rcu_offline_cpu(int cpu)
-{
-}
-
-#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
-
-void __cpuinit rcu_online_cpu(int cpu)
-{
- unsigned long flags;
- struct rcu_data *rdp;
-
- spin_lock_irqsave(&rcu_ctrlblk.fliplock, flags);
- cpumask_set_cpu(cpu, to_cpumask(rcu_cpu_online_map));
- spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags);
-
- /*
- * The rcu_sched grace-period processing might have bypassed
- * this CPU, given that it was not in the rcu_cpu_online_map
- * when the grace-period scan started. This means that the
- * grace-period task might sleep. So make sure that if this
- * should happen, the first callback posted to this CPU will
- * wake up the grace-period task if need be.
- */
-
- rdp = RCU_DATA_CPU(cpu);
- spin_lock_irqsave(&rdp->lock, flags);
- rdp->rcu_sched_sleeping = 1;
- spin_unlock_irqrestore(&rdp->lock, flags);
-}
-
-static void rcu_process_callbacks(struct softirq_action *unused)
-{
- unsigned long flags;
- struct rcu_head *next, *list;
- struct rcu_data *rdp;
-
- local_irq_save(flags);
- rdp = RCU_DATA_ME();
- spin_lock(&rdp->lock);
- list = rdp->donelist;
- if (list == NULL) {
- spin_unlock_irqrestore(&rdp->lock, flags);
- return;
- }
- rdp->donelist = NULL;
- rdp->donetail = &rdp->donelist;
- RCU_TRACE_RDP(rcupreempt_trace_done_remove, rdp);
- spin_unlock_irqrestore(&rdp->lock, flags);
- while (list) {
- next = list->next;
- list->func(list);
- list = next;
- RCU_TRACE_ME(rcupreempt_trace_invoke);
- }
-}
-
-void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
-{
- unsigned long flags;
- struct rcu_data *rdp;
-
- head->func = func;
- head->next = NULL;
- local_irq_save(flags);
- rdp = RCU_DATA_ME();
- spin_lock(&rdp->lock);
- __rcu_advance_callbacks(rdp);
- *rdp->nexttail = head;
- rdp->nexttail = &head->next;
- RCU_TRACE_RDP(rcupreempt_trace_next_add, rdp);
- spin_unlock_irqrestore(&rdp->lock, flags);
-}
-EXPORT_SYMBOL_GPL(call_rcu);
-
-void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
-{
- unsigned long flags;
- struct rcu_data *rdp;
- int wake_gp = 0;
-
- head->func = func;
- head->next = NULL;
- local_irq_save(flags);
- rdp = RCU_DATA_ME();
- spin_lock(&rdp->lock);
- *rdp->nextschedtail = head;
- rdp->nextschedtail = &head->next;
- if (rdp->rcu_sched_sleeping) {
-
- /* Grace-period processing might be sleeping... */
-
- rdp->rcu_sched_sleeping = 0;
- wake_gp = 1;
- }
- spin_unlock_irqrestore(&rdp->lock, flags);
- if (wake_gp) {
-
- /* Wake up grace-period processing, unless someone beat us. */
-
- spin_lock_irqsave(&rcu_ctrlblk.schedlock, flags);
- if (rcu_ctrlblk.sched_sleep != rcu_sched_sleeping)
- wake_gp = 0;
- rcu_ctrlblk.sched_sleep = rcu_sched_not_sleeping;
- spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags);
- if (wake_gp)
- wake_up_interruptible(&rcu_ctrlblk.sched_wq);
- }
-}
-EXPORT_SYMBOL_GPL(call_rcu_sched);
-
-/*
- * Wait until all currently running preempt_disable() code segments
- * (including hardware-irq-disable segments) complete. Note that
- * in -rt this does -not- necessarily result in all currently executing
- * interrupt -handlers- having completed.
- */
-void __synchronize_sched(void)
-{
- struct rcu_synchronize rcu;
-
- if (num_online_cpus() == 1)
- return; /* blocking is gp if only one CPU! */
-
- init_completion(&rcu.completion);
- /* Will wake me after RCU finished. */
- call_rcu_sched(&rcu.head, wakeme_after_rcu);
- /* Wait for it. */
- wait_for_completion(&rcu.completion);
-}
-EXPORT_SYMBOL_GPL(__synchronize_sched);
-
-/*
- * kthread function that manages call_rcu_sched grace periods.
- */
-static int rcu_sched_grace_period(void *arg)
-{
- int couldsleep; /* might sleep after current pass. */
- int couldsleepnext = 0; /* might sleep after next pass. */
- int cpu;
- unsigned long flags;
- struct rcu_data *rdp;
- int ret;
-
- /*
- * Each pass through the following loop handles one
- * rcu_sched grace period cycle.
- */
- do {
- /* Save each CPU's current state. */
-
- for_each_online_cpu(cpu) {
- dyntick_save_progress_counter_sched(cpu);
- save_qsctr_sched(cpu);
- }
-
- /*
- * Sleep for about an RCU grace-period's worth to
- * allow better batching and to consume less CPU.
- */
- schedule_timeout_interruptible(RCU_SCHED_BATCH_TIME);
-
- /*
- * If there was nothing to do last time, prepare to
- * sleep at the end of the current grace period cycle.
- */
- couldsleep = couldsleepnext;
- couldsleepnext = 1;
- if (couldsleep) {
- spin_lock_irqsave(&rcu_ctrlblk.schedlock, flags);
- rcu_ctrlblk.sched_sleep = rcu_sched_sleep_prep;
- spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags);
- }
-
- /*
- * Wait on each CPU in turn to have either visited
- * a quiescent state or been in dynticks-idle mode.
- */
- for_each_online_cpu(cpu) {
- while (rcu_qsctr_inc_needed(cpu) &&
- rcu_qsctr_inc_needed_dyntick(cpu)) {
- /* resched_cpu(cpu); @@@ */
- schedule_timeout_interruptible(1);
- }
- }
-
- /* Advance callbacks for each CPU. */
-
- for_each_online_cpu(cpu) {
-
- rdp = RCU_DATA_CPU(cpu);
- spin_lock_irqsave(&rdp->lock, flags);
-
- /*
- * We are running on this CPU irq-disabled, so no
- * CPU can go offline until we re-enable irqs.
- * The current CPU might have already gone
- * offline (between the for_each_offline_cpu and
- * the spin_lock_irqsave), but in that case all its
- * callback lists will be empty, so no harm done.
- *
- * Advance the callbacks! We share normal RCU's
- * donelist, since callbacks are invoked the
- * same way in either case.
- */
- if (rdp->waitschedlist != NULL) {
- *rdp->donetail = rdp->waitschedlist;
- rdp->donetail = rdp->waitschedtail;
-
- /*
- * Next rcu_check_callbacks() will
- * do the required raise_softirq().
- */
- }
- if (rdp->nextschedlist != NULL) {
- rdp->waitschedlist = rdp->nextschedlist;
- rdp->waitschedtail = rdp->nextschedtail;
- couldsleep = 0;
- couldsleepnext = 0;
- } else {
- rdp->waitschedlist = NULL;
- rdp->waitschedtail = &rdp->waitschedlist;
- }
- rdp->nextschedlist = NULL;
- rdp->nextschedtail = &rdp->nextschedlist;
-
- /* Mark sleep intention. */
-
- rdp->rcu_sched_sleeping = couldsleep;
-
- spin_unlock_irqrestore(&rdp->lock, flags);
- }
-
- /* If we saw callbacks on the last scan, go deal with them. */
-
- if (!couldsleep)
- continue;
-
- /* Attempt to block... */
-
- spin_lock_irqsave(&rcu_ctrlblk.schedlock, flags);
- if (rcu_ctrlblk.sched_sleep != rcu_sched_sleep_prep) {
-
- /*
- * Someone posted a callback after we scanned.
- * Go take care of it.
- */
- spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags);
- couldsleepnext = 0;
- continue;
- }
-
- /* Block until the next person posts a callback. */
-
- rcu_ctrlblk.sched_sleep = rcu_sched_sleeping;
- spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags);
- ret = 0; /* unused */
- __wait_event_interruptible(rcu_ctrlblk.sched_wq,
- rcu_ctrlblk.sched_sleep != rcu_sched_sleeping,
- ret);
-
- couldsleepnext = 0;
-
- } while (!kthread_should_stop());
-
- return (0);
-}
-
-/*
- * Check to see if any future RCU-related work will need to be done
- * by the current CPU, even if none need be done immediately, returning
- * 1 if so. Assumes that notifiers would take care of handling any
- * outstanding requests from the RCU core.
- *
- * This function is part of the RCU implementation; it is -not-
- * an exported member of the RCU API.
- */
-int rcu_needs_cpu(int cpu)
-{
- struct rcu_data *rdp = RCU_DATA_CPU(cpu);
-
- return (rdp->donelist != NULL ||
- !!rdp->waitlistcount ||
- rdp->nextlist != NULL ||
- rdp->nextschedlist != NULL ||
- rdp->waitschedlist != NULL);
-}
-
-int rcu_pending(int cpu)
-{
- struct rcu_data *rdp = RCU_DATA_CPU(cpu);
-
- /* The CPU has at least one callback queued somewhere. */
-
- if (rdp->donelist != NULL ||
- !!rdp->waitlistcount ||
- rdp->nextlist != NULL ||
- rdp->nextschedlist != NULL ||
- rdp->waitschedlist != NULL)
- return 1;
-
- /* The RCU core needs an acknowledgement from this CPU. */
-
- if ((per_cpu(rcu_flip_flag, cpu) == rcu_flipped) ||
- (per_cpu(rcu_mb_flag, cpu) == rcu_mb_needed))
- return 1;
-
- /* This CPU has fallen behind the global grace-period number. */
-
- if (rdp->completed != rcu_ctrlblk.completed)
- return 1;
-
- /* Nothing needed from this CPU. */
-
- return 0;
-}
-
-static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
-{
- long cpu = (long)hcpu;
-
- switch (action) {
- case CPU_UP_PREPARE:
- case CPU_UP_PREPARE_FROZEN:
- rcu_online_cpu(cpu);
- break;
- case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- rcu_offline_cpu(cpu);
- break;
- default:
- break;
- }
- return NOTIFY_OK;
-}
-
-static struct notifier_block __cpuinitdata rcu_nb = {
- .notifier_call = rcu_cpu_notify,
-};
-
-void __init __rcu_init(void)
-{
- int cpu;
- int i;
- struct rcu_data *rdp;
-
- printk(KERN_NOTICE "Preemptible RCU implementation.\n");
- for_each_possible_cpu(cpu) {
- rdp = RCU_DATA_CPU(cpu);
- spin_lock_init(&rdp->lock);
- rdp->completed = 0;
- rdp->waitlistcount = 0;
- rdp->nextlist = NULL;
- rdp->nexttail = &rdp->nextlist;
- for (i = 0; i < GP_STAGES; i++) {
- rdp->waitlist[i] = NULL;
- rdp->waittail[i] = &rdp->waitlist[i];
- }
- rdp->donelist = NULL;
- rdp->donetail = &rdp->donelist;
- rdp->rcu_flipctr[0] = 0;
- rdp->rcu_flipctr[1] = 0;
- rdp->nextschedlist = NULL;
- rdp->nextschedtail = &rdp->nextschedlist;
- rdp->waitschedlist = NULL;
- rdp->waitschedtail = &rdp->waitschedlist;
- rdp->rcu_sched_sleeping = 0;
- }
- register_cpu_notifier(&rcu_nb);
-
- /*
- * We don't need protection against CPU-Hotplug here
- * since
- * a) If a CPU comes online while we are iterating over the
- * cpu_online_mask below, we would only end up making a
- * duplicate call to rcu_online_cpu() which sets the corresponding
- * CPU's mask in the rcu_cpu_online_map.
- *
- * b) A CPU cannot go offline at this point in time since the user
- * does not have access to the sysfs interface, nor do we
- * suspend the system.
- */
- for_each_online_cpu(cpu)
- rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long) cpu);
-
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
-}
-
-/*
- * Late-boot-time RCU initialization that must wait until after scheduler
- * has been initialized.
- */
-void __init rcu_init_sched(void)
-{
- rcu_sched_grace_period_task = kthread_run(rcu_sched_grace_period,
- NULL,
- "rcu_sched_grace_period");
- WARN_ON(IS_ERR(rcu_sched_grace_period_task));
-}
-
-#ifdef CONFIG_RCU_TRACE
-long *rcupreempt_flipctr(int cpu)
-{
- return &RCU_DATA_CPU(cpu)->rcu_flipctr[0];
-}
-EXPORT_SYMBOL_GPL(rcupreempt_flipctr);
-
-int rcupreempt_flip_flag(int cpu)
-{
- return per_cpu(rcu_flip_flag, cpu);
-}
-EXPORT_SYMBOL_GPL(rcupreempt_flip_flag);
-
-int rcupreempt_mb_flag(int cpu)
-{
- return per_cpu(rcu_mb_flag, cpu);
-}
-EXPORT_SYMBOL_GPL(rcupreempt_mb_flag);
-
-char *rcupreempt_try_flip_state_name(void)
-{
- return rcu_try_flip_state_names[rcu_ctrlblk.rcu_try_flip_state];
-}
-EXPORT_SYMBOL_GPL(rcupreempt_try_flip_state_name);
-
-struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu)
-{
- struct rcu_data *rdp = RCU_DATA_CPU(cpu);
-
- return &rdp->trace;
-}
-EXPORT_SYMBOL_GPL(rcupreempt_trace_cpu);
-
-#endif /* #ifdef RCU_TRACE */
diff --git a/kernel/rcupreempt_trace.c b/kernel/rcupreempt_trace.c
deleted file mode 100644
index 7c2665cac172..000000000000
--- a/kernel/rcupreempt_trace.c
+++ /dev/null
@@ -1,334 +0,0 @@
-/*
- * Read-Copy Update tracing for realtime implementation
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright IBM Corporation, 2006
- *
- * Papers: http://www.rdrop.com/users/paulmck/RCU
- *
- * For detailed explanation of Read-Copy Update mechanism see -
- * Documentation/RCU/ *.txt
- *
- */
-#include <linux/types.h>
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/spinlock.h>
-#include <linux/smp.h>
-#include <linux/rcupdate.h>
-#include <linux/interrupt.h>
-#include <linux/sched.h>
-#include <asm/atomic.h>
-#include <linux/bitops.h>
-#include <linux/module.h>
-#include <linux/completion.h>
-#include <linux/moduleparam.h>
-#include <linux/percpu.h>
-#include <linux/notifier.h>
-#include <linux/cpu.h>
-#include <linux/mutex.h>
-#include <linux/rcupreempt_trace.h>
-#include <linux/debugfs.h>
-
-static struct mutex rcupreempt_trace_mutex;
-static char *rcupreempt_trace_buf;
-#define RCUPREEMPT_TRACE_BUF_SIZE 4096
-
-void rcupreempt_trace_move2done(struct rcupreempt_trace *trace)
-{
- trace->done_length += trace->wait_length;
- trace->done_add += trace->wait_length;
- trace->wait_length = 0;
-}
-void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace)
-{
- trace->wait_length += trace->next_length;
- trace->wait_add += trace->next_length;
- trace->next_length = 0;
-}
-void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace)
-{
- atomic_inc(&trace->rcu_try_flip_1);
-}
-void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace)
-{
- atomic_inc(&trace->rcu_try_flip_e1);
-}
-void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_i1++;
-}
-void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_ie1++;
-}
-void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_g1++;
-}
-void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_a1++;
-}
-void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_ae1++;
-}
-void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_a2++;
-}
-void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_z1++;
-}
-void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_ze1++;
-}
-void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_z2++;
-}
-void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_m1++;
-}
-void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_me1++;
-}
-void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace)
-{
- trace->rcu_try_flip_m2++;
-}
-void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace)
-{
- trace->rcu_check_callbacks++;
-}
-void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace)
-{
- trace->done_remove += trace->done_length;
- trace->done_length = 0;
-}
-void rcupreempt_trace_invoke(struct rcupreempt_trace *trace)
-{
- atomic_inc(&trace->done_invoked);
-}
-void rcupreempt_trace_next_add(struct rcupreempt_trace *trace)
-{
- trace->next_add++;
- trace->next_length++;
-}
-
-static void rcupreempt_trace_sum(struct rcupreempt_trace *sp)
-{
- struct rcupreempt_trace *cp;
- int cpu;
-
- memset(sp, 0, sizeof(*sp));
- for_each_possible_cpu(cpu) {
- cp = rcupreempt_trace_cpu(cpu);
- sp->next_length += cp->next_length;
- sp->next_add += cp->next_add;
- sp->wait_length += cp->wait_length;
- sp->wait_add += cp->wait_add;
- sp->done_length += cp->done_length;
- sp->done_add += cp->done_add;
- sp->done_remove += cp->done_remove;
- atomic_add(atomic_read(&cp->done_invoked), &sp->done_invoked);
- sp->rcu_check_callbacks += cp->rcu_check_callbacks;
- atomic_add(atomic_read(&cp->rcu_try_flip_1),
- &sp->rcu_try_flip_1);
- atomic_add(atomic_read(&cp->rcu_try_flip_e1),
- &sp->rcu_try_flip_e1);
- sp->rcu_try_flip_i1 += cp->rcu_try_flip_i1;
- sp->rcu_try_flip_ie1 += cp->rcu_try_flip_ie1;
- sp->rcu_try_flip_g1 += cp->rcu_try_flip_g1;
- sp->rcu_try_flip_a1 += cp->rcu_try_flip_a1;
- sp->rcu_try_flip_ae1 += cp->rcu_try_flip_ae1;
- sp->rcu_try_flip_a2 += cp->rcu_try_flip_a2;
- sp->rcu_try_flip_z1 += cp->rcu_try_flip_z1;
- sp->rcu_try_flip_ze1 += cp->rcu_try_flip_ze1;
- sp->rcu_try_flip_z2 += cp->rcu_try_flip_z2;
- sp->rcu_try_flip_m1 += cp->rcu_try_flip_m1;
- sp->rcu_try_flip_me1 += cp->rcu_try_flip_me1;
- sp->rcu_try_flip_m2 += cp->rcu_try_flip_m2;
- }
-}
-
-static ssize_t rcustats_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
-{
- struct rcupreempt_trace trace;
- ssize_t bcount;
- int cnt = 0;
-
- rcupreempt_trace_sum(&trace);
- mutex_lock(&rcupreempt_trace_mutex);
- snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "ggp=%ld rcc=%ld\n",
- rcu_batches_completed(),
- trace.rcu_check_callbacks);
- snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "na=%ld nl=%ld wa=%ld wl=%ld da=%ld dl=%ld dr=%ld di=%d\n"
- "1=%d e1=%d i1=%ld ie1=%ld g1=%ld a1=%ld ae1=%ld a2=%ld\n"
- "z1=%ld ze1=%ld z2=%ld m1=%ld me1=%ld m2=%ld\n",
-
- trace.next_add, trace.next_length,
- trace.wait_add, trace.wait_length,
- trace.done_add, trace.done_length,
- trace.done_remove, atomic_read(&trace.done_invoked),
- atomic_read(&trace.rcu_try_flip_1),
- atomic_read(&trace.rcu_try_flip_e1),
- trace.rcu_try_flip_i1, trace.rcu_try_flip_ie1,
- trace.rcu_try_flip_g1,
- trace.rcu_try_flip_a1, trace.rcu_try_flip_ae1,
- trace.rcu_try_flip_a2,
- trace.rcu_try_flip_z1, trace.rcu_try_flip_ze1,
- trace.rcu_try_flip_z2,
- trace.rcu_try_flip_m1, trace.rcu_try_flip_me1,
- trace.rcu_try_flip_m2);
- bcount = simple_read_from_buffer(buffer, count, ppos,
- rcupreempt_trace_buf, strlen(rcupreempt_trace_buf));
- mutex_unlock(&rcupreempt_trace_mutex);
- return bcount;
-}
-
-static ssize_t rcugp_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
-{
- long oldgp = rcu_batches_completed();
- ssize_t bcount;
-
- mutex_lock(&rcupreempt_trace_mutex);
- synchronize_rcu();
- snprintf(rcupreempt_trace_buf, RCUPREEMPT_TRACE_BUF_SIZE,
- "oldggp=%ld newggp=%ld\n", oldgp, rcu_batches_completed());
- bcount = simple_read_from_buffer(buffer, count, ppos,
- rcupreempt_trace_buf, strlen(rcupreempt_trace_buf));
- mutex_unlock(&rcupreempt_trace_mutex);
- return bcount;
-}
-
-static ssize_t rcuctrs_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
-{
- int cnt = 0;
- int cpu;
- int f = rcu_batches_completed() & 0x1;
- ssize_t bcount;
-
- mutex_lock(&rcupreempt_trace_mutex);
-
- cnt += snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE,
- "CPU last cur F M\n");
- for_each_online_cpu(cpu) {
- long *flipctr = rcupreempt_flipctr(cpu);
- cnt += snprintf(&rcupreempt_trace_buf[cnt],
- RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "%3d %4ld %3ld %d %d\n",
- cpu,
- flipctr[!f],
- flipctr[f],
- rcupreempt_flip_flag(cpu),
- rcupreempt_mb_flag(cpu));
- }
- cnt += snprintf(&rcupreempt_trace_buf[cnt],
- RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "ggp = %ld, state = %s\n",
- rcu_batches_completed(),
- rcupreempt_try_flip_state_name());
- cnt += snprintf(&rcupreempt_trace_buf[cnt],
- RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "\n");
- bcount = simple_read_from_buffer(buffer, count, ppos,
- rcupreempt_trace_buf, strlen(rcupreempt_trace_buf));
- mutex_unlock(&rcupreempt_trace_mutex);
- return bcount;
-}
-
-static struct file_operations rcustats_fops = {
- .owner = THIS_MODULE,
- .read = rcustats_read,
-};
-
-static struct file_operations rcugp_fops = {
- .owner = THIS_MODULE,
- .read = rcugp_read,
-};
-
-static struct file_operations rcuctrs_fops = {
- .owner = THIS_MODULE,
- .read = rcuctrs_read,
-};
-
-static struct dentry *rcudir, *statdir, *ctrsdir, *gpdir;
-static int rcupreempt_debugfs_init(void)
-{
- rcudir = debugfs_create_dir("rcu", NULL);
- if (!rcudir)
- goto out;
- statdir = debugfs_create_file("rcustats", 0444, rcudir,
- NULL, &rcustats_fops);
- if (!statdir)
- goto free_out;
-
- gpdir = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
- if (!gpdir)
- goto free_out;
-
- ctrsdir = debugfs_create_file("rcuctrs", 0444, rcudir,
- NULL, &rcuctrs_fops);
- if (!ctrsdir)
- goto free_out;
- return 0;
-free_out:
- if (statdir)
- debugfs_remove(statdir);
- if (gpdir)
- debugfs_remove(gpdir);
- debugfs_remove(rcudir);
-out:
- return 1;
-}
-
-static int __init rcupreempt_trace_init(void)
-{
- int ret;
-
- mutex_init(&rcupreempt_trace_mutex);
- rcupreempt_trace_buf = kmalloc(RCUPREEMPT_TRACE_BUF_SIZE, GFP_KERNEL);
- if (!rcupreempt_trace_buf)
- return 1;
- ret = rcupreempt_debugfs_init();
- if (ret)
- kfree(rcupreempt_trace_buf);
- return ret;
-}
-
-static void __exit rcupreempt_trace_cleanup(void)
-{
- debugfs_remove(statdir);
- debugfs_remove(gpdir);
- debugfs_remove(ctrsdir);
- debugfs_remove(rcudir);
- kfree(rcupreempt_trace_buf);
-}
-
-
-module_init(rcupreempt_trace_init);
-module_exit(rcupreempt_trace_cleanup);
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 9b4a975a4b4a..b33db539a8ad 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -257,14 +257,14 @@ struct rcu_torture_ops {
void (*init)(void);
void (*cleanup)(void);
int (*readlock)(void);
- void (*readdelay)(struct rcu_random_state *rrsp);
+ void (*read_delay)(struct rcu_random_state *rrsp);
void (*readunlock)(int idx);
int (*completed)(void);
- void (*deferredfree)(struct rcu_torture *p);
+ void (*deferred_free)(struct rcu_torture *p);
void (*sync)(void);
void (*cb_barrier)(void);
int (*stats)(char *page);
- int irqcapable;
+ int irq_capable;
char *name;
};
static struct rcu_torture_ops *cur_ops = NULL;
@@ -320,7 +320,7 @@ rcu_torture_cb(struct rcu_head *p)
rp->rtort_mbtest = 0;
rcu_torture_free(rp);
} else
- cur_ops->deferredfree(rp);
+ cur_ops->deferred_free(rp);
}
static void rcu_torture_deferred_free(struct rcu_torture *p)
@@ -329,18 +329,18 @@ static void rcu_torture_deferred_free(struct rcu_torture *p)
}
static struct rcu_torture_ops rcu_ops = {
- .init = NULL,
- .cleanup = NULL,
- .readlock = rcu_torture_read_lock,
- .readdelay = rcu_read_delay,
- .readunlock = rcu_torture_read_unlock,
- .completed = rcu_torture_completed,
- .deferredfree = rcu_torture_deferred_free,
- .sync = synchronize_rcu,
- .cb_barrier = rcu_barrier,
- .stats = NULL,
- .irqcapable = 1,
- .name = "rcu"
+ .init = NULL,
+ .cleanup = NULL,
+ .readlock = rcu_torture_read_lock,
+ .read_delay = rcu_read_delay,
+ .readunlock = rcu_torture_read_unlock,
+ .completed = rcu_torture_completed,
+ .deferred_free = rcu_torture_deferred_free,
+ .sync = synchronize_rcu,
+ .cb_barrier = rcu_barrier,
+ .stats = NULL,
+ .irq_capable = 1,
+ .name = "rcu"
};
static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
@@ -370,18 +370,18 @@ static void rcu_sync_torture_init(void)
}
static struct rcu_torture_ops rcu_sync_ops = {
- .init = rcu_sync_torture_init,
- .cleanup = NULL,
- .readlock = rcu_torture_read_lock,
- .readdelay = rcu_read_delay,
- .readunlock = rcu_torture_read_unlock,
- .completed = rcu_torture_completed,
- .deferredfree = rcu_sync_torture_deferred_free,
- .sync = synchronize_rcu,
- .cb_barrier = NULL,
- .stats = NULL,
- .irqcapable = 1,
- .name = "rcu_sync"
+ .init = rcu_sync_torture_init,
+ .cleanup = NULL,
+ .readlock = rcu_torture_read_lock,
+ .read_delay = rcu_read_delay,
+ .readunlock = rcu_torture_read_unlock,
+ .completed = rcu_torture_completed,
+ .deferred_free = rcu_sync_torture_deferred_free,
+ .sync = synchronize_rcu,
+ .cb_barrier = NULL,
+ .stats = NULL,
+ .irq_capable = 1,
+ .name = "rcu_sync"
};
/*
@@ -432,33 +432,33 @@ static void rcu_bh_torture_synchronize(void)
}
static struct rcu_torture_ops rcu_bh_ops = {
- .init = NULL,
- .cleanup = NULL,
- .readlock = rcu_bh_torture_read_lock,
- .readdelay = rcu_read_delay, /* just reuse rcu's version. */
- .readunlock = rcu_bh_torture_read_unlock,
- .completed = rcu_bh_torture_completed,
- .deferredfree = rcu_bh_torture_deferred_free,
- .sync = rcu_bh_torture_synchronize,
- .cb_barrier = rcu_barrier_bh,
- .stats = NULL,
- .irqcapable = 1,
- .name = "rcu_bh"
+ .init = NULL,
+ .cleanup = NULL,
+ .readlock = rcu_bh_torture_read_lock,
+ .read_delay = rcu_read_delay, /* just reuse rcu's version. */
+ .readunlock = rcu_bh_torture_read_unlock,
+ .completed = rcu_bh_torture_completed,
+ .deferred_free = rcu_bh_torture_deferred_free,
+ .sync = rcu_bh_torture_synchronize,
+ .cb_barrier = rcu_barrier_bh,
+ .stats = NULL,
+ .irq_capable = 1,
+ .name = "rcu_bh"
};
static struct rcu_torture_ops rcu_bh_sync_ops = {
- .init = rcu_sync_torture_init,
- .cleanup = NULL,
- .readlock = rcu_bh_torture_read_lock,
- .readdelay = rcu_read_delay, /* just reuse rcu's version. */
- .readunlock = rcu_bh_torture_read_unlock,
- .completed = rcu_bh_torture_completed,
- .deferredfree = rcu_sync_torture_deferred_free,
- .sync = rcu_bh_torture_synchronize,
- .cb_barrier = NULL,
- .stats = NULL,
- .irqcapable = 1,
- .name = "rcu_bh_sync"
+ .init = rcu_sync_torture_init,
+ .cleanup = NULL,
+ .readlock = rcu_bh_torture_read_lock,
+ .read_delay = rcu_read_delay, /* just reuse rcu's version. */
+ .readunlock = rcu_bh_torture_read_unlock,
+ .completed = rcu_bh_torture_completed,
+ .deferred_free = rcu_sync_torture_deferred_free,
+ .sync = rcu_bh_torture_synchronize,
+ .cb_barrier = NULL,
+ .stats = NULL,
+ .irq_capable = 1,
+ .name = "rcu_bh_sync"
};
/*
@@ -530,17 +530,17 @@ static int srcu_torture_stats(char *page)
}
static struct rcu_torture_ops srcu_ops = {
- .init = srcu_torture_init,
- .cleanup = srcu_torture_cleanup,
- .readlock = srcu_torture_read_lock,
- .readdelay = srcu_read_delay,
- .readunlock = srcu_torture_read_unlock,
- .completed = srcu_torture_completed,
- .deferredfree = rcu_sync_torture_deferred_free,
- .sync = srcu_torture_synchronize,
- .cb_barrier = NULL,
- .stats = srcu_torture_stats,
- .name = "srcu"
+ .init = srcu_torture_init,
+ .cleanup = srcu_torture_cleanup,
+ .readlock = srcu_torture_read_lock,
+ .read_delay = srcu_read_delay,
+ .readunlock = srcu_torture_read_unlock,
+ .completed = srcu_torture_completed,
+ .deferred_free = rcu_sync_torture_deferred_free,
+ .sync = srcu_torture_synchronize,
+ .cb_barrier = NULL,
+ .stats = srcu_torture_stats,
+ .name = "srcu"
};
/*
@@ -574,32 +574,49 @@ static void sched_torture_synchronize(void)
}
static struct rcu_torture_ops sched_ops = {
- .init = rcu_sync_torture_init,
- .cleanup = NULL,
- .readlock = sched_torture_read_lock,
- .readdelay = rcu_read_delay, /* just reuse rcu's version. */
- .readunlock = sched_torture_read_unlock,
- .completed = sched_torture_completed,
- .deferredfree = rcu_sched_torture_deferred_free,
- .sync = sched_torture_synchronize,
- .cb_barrier = rcu_barrier_sched,
- .stats = NULL,
- .irqcapable = 1,
- .name = "sched"
+ .init = rcu_sync_torture_init,
+ .cleanup = NULL,
+ .readlock = sched_torture_read_lock,
+ .read_delay = rcu_read_delay, /* just reuse rcu's version. */
+ .readunlock = sched_torture_read_unlock,
+ .completed = sched_torture_completed,
+ .deferred_free = rcu_sched_torture_deferred_free,
+ .sync = sched_torture_synchronize,
+ .cb_barrier = rcu_barrier_sched,
+ .stats = NULL,
+ .irq_capable = 1,
+ .name = "sched"
};
static struct rcu_torture_ops sched_ops_sync = {
- .init = rcu_sync_torture_init,
- .cleanup = NULL,
- .readlock = sched_torture_read_lock,
- .readdelay = rcu_read_delay, /* just reuse rcu's version. */
- .readunlock = sched_torture_read_unlock,
- .completed = sched_torture_completed,
- .deferredfree = rcu_sync_torture_deferred_free,
- .sync = sched_torture_synchronize,
- .cb_barrier = NULL,
- .stats = NULL,
- .name = "sched_sync"
+ .init = rcu_sync_torture_init,
+ .cleanup = NULL,
+ .readlock = sched_torture_read_lock,
+ .read_delay = rcu_read_delay, /* just reuse rcu's version. */
+ .readunlock = sched_torture_read_unlock,
+ .completed = sched_torture_completed,
+ .deferred_free = rcu_sync_torture_deferred_free,
+ .sync = sched_torture_synchronize,
+ .cb_barrier = NULL,
+ .stats = NULL,
+ .name = "sched_sync"
+};
+
+extern int rcu_expedited_torture_stats(char *page);
+
+static struct rcu_torture_ops sched_expedited_ops = {
+ .init = rcu_sync_torture_init,
+ .cleanup = NULL,
+ .readlock = sched_torture_read_lock,
+ .read_delay = rcu_read_delay, /* just reuse rcu's version. */
+ .readunlock = sched_torture_read_unlock,
+ .completed = sched_torture_completed,
+ .deferred_free = rcu_sync_torture_deferred_free,
+ .sync = synchronize_sched_expedited,
+ .cb_barrier = NULL,
+ .stats = rcu_expedited_torture_stats,
+ .irq_capable = 1,
+ .name = "sched_expedited"
};
/*
@@ -635,7 +652,7 @@ rcu_torture_writer(void *arg)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
old_rp->rtort_pipe_count++;
- cur_ops->deferredfree(old_rp);
+ cur_ops->deferred_free(old_rp);
}
rcu_torture_current_version++;
oldbatch = cur_ops->completed();
@@ -700,7 +717,7 @@ static void rcu_torture_timer(unsigned long unused)
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
spin_lock(&rand_lock);
- cur_ops->readdelay(&rand);
+ cur_ops->read_delay(&rand);
n_rcu_torture_timers++;
spin_unlock(&rand_lock);
preempt_disable();
@@ -738,11 +755,11 @@ rcu_torture_reader(void *arg)
VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
set_user_nice(current, 19);
- if (irqreader && cur_ops->irqcapable)
+ if (irqreader && cur_ops->irq_capable)
setup_timer_on_stack(&t, rcu_torture_timer, 0);
do {
- if (irqreader && cur_ops->irqcapable) {
+ if (irqreader && cur_ops->irq_capable) {
if (!timer_pending(&t))
mod_timer(&t, 1);
}
@@ -757,7 +774,7 @@ rcu_torture_reader(void *arg)
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
- cur_ops->readdelay(&rand);
+ cur_ops->read_delay(&rand);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
@@ -778,7 +795,7 @@ rcu_torture_reader(void *arg)
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
rcutorture_shutdown_absorb("rcu_torture_reader");
- if (irqreader && cur_ops->irqcapable)
+ if (irqreader && cur_ops->irq_capable)
del_timer_sync(&t);
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
@@ -1078,6 +1095,7 @@ rcu_torture_init(void)
int firsterr = 0;
static struct rcu_torture_ops *torture_ops[] =
{ &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
+ &sched_expedited_ops,
&srcu_ops, &sched_ops, &sched_ops_sync, };
mutex_lock(&fullstop_mutex);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 9c5fa9fc57ec..6b11b07cfe7f 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -47,6 +47,8 @@
#include <linux/mutex.h>
#include <linux/time.h>
+#include "rcutree.h"
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key rcu_lock_key;
struct lockdep_map rcu_lock_map =
@@ -73,30 +75,59 @@ EXPORT_SYMBOL_GPL(rcu_lock_map);
.n_force_qs_ngp = 0, \
}
-struct rcu_state rcu_state = RCU_STATE_INITIALIZER(rcu_state);
-DEFINE_PER_CPU(struct rcu_data, rcu_data);
+struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state);
+DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);
struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
+extern long rcu_batches_completed_sched(void);
+static struct rcu_node *rcu_get_root(struct rcu_state *rsp);
+static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp,
+ struct rcu_node *rnp, unsigned long flags);
+static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags);
+#ifdef CONFIG_HOTPLUG_CPU
+static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp);
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+static void __rcu_process_callbacks(struct rcu_state *rsp,
+ struct rcu_data *rdp);
+static void __call_rcu(struct rcu_head *head,
+ void (*func)(struct rcu_head *rcu),
+ struct rcu_state *rsp);
+static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp);
+static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp,
+ int preemptable);
+
+#include "rcutree_plugin.h"
+
/*
- * Increment the quiescent state counter.
- * The counter is a bit degenerated: We do not need to know
+ * Note a quiescent state. Because we do not need to know
* how many quiescent states passed, just if there was at least
- * one since the start of the grace period. Thus just a flag.
+ * one since the start of the grace period, this just sets a flag.
*/
-void rcu_qsctr_inc(int cpu)
+void rcu_sched_qs(int cpu)
{
- struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+ unsigned long flags;
+ struct rcu_data *rdp;
+
+ local_irq_save(flags);
+ rdp = &per_cpu(rcu_sched_data, cpu);
rdp->passed_quiesc = 1;
rdp->passed_quiesc_completed = rdp->completed;
+ rcu_preempt_qs(cpu);
+ local_irq_restore(flags);
}
-void rcu_bh_qsctr_inc(int cpu)
+void rcu_bh_qs(int cpu)
{
- struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
+ unsigned long flags;
+ struct rcu_data *rdp;
+
+ local_irq_save(flags);
+ rdp = &per_cpu(rcu_bh_data, cpu);
rdp->passed_quiesc = 1;
rdp->passed_quiesc_completed = rdp->completed;
+ local_irq_restore(flags);
}
#ifdef CONFIG_NO_HZ
@@ -111,15 +142,16 @@ static int qhimark = 10000; /* If this many pending, ignore blimit. */
static int qlowmark = 100; /* Once only this many pending, use blimit. */
static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
+static int rcu_pending(int cpu);
/*
- * Return the number of RCU batches processed thus far for debug & stats.
+ * Return the number of RCU-sched batches processed thus far for debug & stats.
*/
-long rcu_batches_completed(void)
+long rcu_batches_completed_sched(void)
{
- return rcu_state.completed;
+ return rcu_sched_state.completed;
}
-EXPORT_SYMBOL_GPL(rcu_batches_completed);
+EXPORT_SYMBOL_GPL(rcu_batches_completed_sched);
/*
* Return the number of RCU BH batches processed thus far for debug & stats.
@@ -182,6 +214,10 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
return 1;
}
+ /* If preemptable RCU, no point in sending reschedule IPI. */
+ if (rdp->preemptable)
+ return 0;
+
/* The CPU is online, so send it a reschedule IPI. */
if (rdp->cpu != smp_processor_id())
smp_send_reschedule(rdp->cpu);
@@ -194,7 +230,6 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
#endif /* #ifdef CONFIG_SMP */
#ifdef CONFIG_NO_HZ
-static DEFINE_RATELIMIT_STATE(rcu_rs, 10 * HZ, 5);
/**
* rcu_enter_nohz - inform RCU that current CPU is entering nohz
@@ -214,7 +249,7 @@ void rcu_enter_nohz(void)
rdtp = &__get_cpu_var(rcu_dynticks);
rdtp->dynticks++;
rdtp->dynticks_nesting--;
- WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);
+ WARN_ON_ONCE(rdtp->dynticks & 0x1);
local_irq_restore(flags);
}
@@ -233,7 +268,7 @@ void rcu_exit_nohz(void)
rdtp = &__get_cpu_var(rcu_dynticks);
rdtp->dynticks++;
rdtp->dynticks_nesting++;
- WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs);
+ WARN_ON_ONCE(!(rdtp->dynticks & 0x1));
local_irq_restore(flags);
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
}
@@ -252,7 +287,7 @@ void rcu_nmi_enter(void)
if (rdtp->dynticks & 0x1)
return;
rdtp->dynticks_nmi++;
- WARN_ON_RATELIMIT(!(rdtp->dynticks_nmi & 0x1), &rcu_rs);
+ WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1));
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
}
@@ -271,7 +306,7 @@ void rcu_nmi_exit(void)
return;
smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
rdtp->dynticks_nmi++;
- WARN_ON_RATELIMIT(rdtp->dynticks_nmi & 0x1, &rcu_rs);
+ WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1);
}
/**
@@ -287,7 +322,7 @@ void rcu_irq_enter(void)
if (rdtp->dynticks_nesting++)
return;
rdtp->dynticks++;
- WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs);
+ WARN_ON_ONCE(!(rdtp->dynticks & 0x1));
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
}
@@ -306,10 +341,10 @@ void rcu_irq_exit(void)
return;
smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
rdtp->dynticks++;
- WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);
+ WARN_ON_ONCE(rdtp->dynticks & 0x1);
/* If the interrupt queued a callback, get out of dyntick mode. */
- if (__get_cpu_var(rcu_data).nxtlist ||
+ if (__get_cpu_var(rcu_sched_data).nxtlist ||
__get_cpu_var(rcu_bh_data).nxtlist)
set_need_resched();
}
@@ -462,6 +497,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
printk(KERN_ERR "INFO: RCU detected CPU stalls:");
for (; rnp_cur < rnp_end; rnp_cur++) {
+ rcu_print_task_stall(rnp);
if (rnp_cur->qsmask == 0)
continue;
for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++)
@@ -679,6 +715,19 @@ rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
}
/*
+ * Clean up after the prior grace period and let rcu_start_gp() start up
+ * the next grace period if one is needed. Note that the caller must
+ * hold rnp->lock, as required by rcu_start_gp(), which will release it.
+ */
+static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags)
+ __releases(rnp->lock)
+{
+ rsp->completed = rsp->gpnum;
+ rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
+ rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
+}
+
+/*
* Similar to cpu_quiet(), for which it is a helper function. Allows
* a group of CPUs to be quieted at one go, though all the CPUs in the
* group must be represented by the same leaf rcu_node structure.
@@ -699,7 +748,7 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
return;
}
rnp->qsmask &= ~mask;
- if (rnp->qsmask != 0) {
+ if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) {
/* Other bits still set at this level, so done. */
spin_unlock_irqrestore(&rnp->lock, flags);
@@ -719,14 +768,10 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
/*
* Get here if we are the last CPU to pass through a quiescent
- * state for this grace period. Clean up and let rcu_start_gp()
- * start up the next grace period if one is needed. Note that
- * we still hold rnp->lock, as required by rcu_start_gp(), which
- * will release it.
+ * state for this grace period. Invoke cpu_quiet_msk_finish()
+ * to clean up and start the next grace period if one is needed.
*/
- rsp->completed = rsp->gpnum;
- rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
- rcu_start_gp(rsp, flags); /* releases rnp->lock. */
+ cpu_quiet_msk_finish(rsp, flags); /* releases rnp->lock. */
}
/*
@@ -833,11 +878,12 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
spin_lock(&rnp->lock); /* irqs already disabled. */
rnp->qsmaskinit &= ~mask;
if (rnp->qsmaskinit != 0) {
- spin_unlock(&rnp->lock); /* irqs already disabled. */
+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
break;
}
+ rcu_preempt_offline_tasks(rsp, rnp);
mask = rnp->grpmask;
- spin_unlock(&rnp->lock); /* irqs already disabled. */
+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
rnp = rnp->parent;
} while (rnp != NULL);
lastcomp = rsp->completed;
@@ -850,7 +896,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
/*
* Move callbacks from the outgoing CPU to the running CPU.
* Note that the outgoing CPU is now quiscent, so it is now
- * (uncharacteristically) safe to access it rcu_data structure.
+ * (uncharacteristically) safe to access its rcu_data structure.
* Note also that we must carefully retain the order of the
* outgoing CPU's callbacks in order for rcu_barrier() to work
* correctly. Finally, note that we start all the callbacks
@@ -881,8 +927,9 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
*/
static void rcu_offline_cpu(int cpu)
{
- __rcu_offline_cpu(cpu, &rcu_state);
+ __rcu_offline_cpu(cpu, &rcu_sched_state);
__rcu_offline_cpu(cpu, &rcu_bh_state);
+ rcu_preempt_offline_cpu(cpu);
}
#else /* #ifdef CONFIG_HOTPLUG_CPU */
@@ -968,6 +1015,8 @@ static void rcu_do_batch(struct rcu_data *rdp)
*/
void rcu_check_callbacks(int cpu, int user)
{
+ if (!rcu_pending(cpu))
+ return; /* if nothing for RCU to do. */
if (user ||
(idle_cpu(cpu) && rcu_scheduler_active &&
!in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
@@ -976,17 +1025,16 @@ void rcu_check_callbacks(int cpu, int user)
* Get here if this CPU took its interrupt from user
* mode or from the idle loop, and if this is not a
* nested interrupt. In this case, the CPU is in
- * a quiescent state, so count it.
+ * a quiescent state, so note it.
*
* No memory barrier is required here because both
- * rcu_qsctr_inc() and rcu_bh_qsctr_inc() reference
- * only CPU-local variables that other CPUs neither
- * access nor modify, at least not while the corresponding
- * CPU is online.
+ * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local
+ * variables that other CPUs neither access nor modify,
+ * at least not while the corresponding CPU is online.
*/
- rcu_qsctr_inc(cpu);
- rcu_bh_qsctr_inc(cpu);
+ rcu_sched_qs(cpu);
+ rcu_bh_qs(cpu);
} else if (!in_softirq()) {
@@ -994,11 +1042,12 @@ void rcu_check_callbacks(int cpu, int user)
* Get here if this CPU did not take its interrupt from
* softirq, in other words, if it is not interrupting
* a rcu_bh read-side critical section. This is an _bh
- * critical section, so count it.
+ * critical section, so note it.
*/
- rcu_bh_qsctr_inc(cpu);
+ rcu_bh_qs(cpu);
}
+ rcu_preempt_check_callbacks(cpu);
raise_softirq(RCU_SOFTIRQ);
}
@@ -1137,6 +1186,8 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
{
unsigned long flags;
+ WARN_ON_ONCE(rdp->beenonline == 0);
+
/*
* If an RCU GP has gone long enough, go check for dyntick
* idle CPUs and, if needed, send resched IPIs.
@@ -1175,8 +1226,10 @@ static void rcu_process_callbacks(struct softirq_action *unused)
*/
smp_mb(); /* See above block comment. */
- __rcu_process_callbacks(&rcu_state, &__get_cpu_var(rcu_data));
+ __rcu_process_callbacks(&rcu_sched_state,
+ &__get_cpu_var(rcu_sched_data));
__rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
+ rcu_preempt_process_callbacks();
/*
* Memory references from any later RCU read-side critical sections
@@ -1232,13 +1285,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
}
/*
- * Queue an RCU callback for invocation after a grace period.
+ * Queue an RCU-sched callback for invocation after a grace period.
*/
-void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
{
- __call_rcu(head, func, &rcu_state);
+ __call_rcu(head, func, &rcu_sched_state);
}
-EXPORT_SYMBOL_GPL(call_rcu);
+EXPORT_SYMBOL_GPL(call_rcu_sched);
/*
* Queue an RCU for invocation after a quicker grace period.
@@ -1310,10 +1363,11 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
* by the current CPU, returning 1 if so. This function is part of the
* RCU implementation; it is -not- an exported member of the RCU API.
*/
-int rcu_pending(int cpu)
+static int rcu_pending(int cpu)
{
- return __rcu_pending(&rcu_state, &per_cpu(rcu_data, cpu)) ||
- __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu));
+ return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) ||
+ __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) ||
+ rcu_preempt_pending(cpu);
}
/*
@@ -1325,27 +1379,46 @@ int rcu_pending(int cpu)
int rcu_needs_cpu(int cpu)
{
/* RCU callbacks either ready or pending? */
- return per_cpu(rcu_data, cpu).nxtlist ||
- per_cpu(rcu_bh_data, cpu).nxtlist;
+ return per_cpu(rcu_sched_data, cpu).nxtlist ||
+ per_cpu(rcu_bh_data, cpu).nxtlist ||
+ rcu_preempt_needs_cpu(cpu);
}
/*
- * Initialize a CPU's per-CPU RCU data. We take this "scorched earth"
- * approach so that we don't have to worry about how long the CPU has
- * been gone, or whether it ever was online previously. We do trust the
- * ->mynode field, as it is constant for a given struct rcu_data and
- * initialized during early boot.
- *
- * Note that only one online or offline event can be happening at a given
- * time. Note also that we can accept some slop in the rsp->completed
- * access due to the fact that this CPU cannot possibly have any RCU
- * callbacks in flight yet.
+ * Do boot-time initialization of a CPU's per-CPU RCU data.
*/
-static void __cpuinit
-rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
+static void __init
+rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
{
unsigned long flags;
int i;
+ struct rcu_data *rdp = rsp->rda[cpu];
+ struct rcu_node *rnp = rcu_get_root(rsp);
+
+ /* Set up local state, ensuring consistent view of global state. */
+ spin_lock_irqsave(&rnp->lock, flags);
+ rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
+ rdp->nxtlist = NULL;
+ for (i = 0; i < RCU_NEXT_SIZE; i++)
+ rdp->nxttail[i] = &rdp->nxtlist;
+ rdp->qlen = 0;
+#ifdef CONFIG_NO_HZ
+ rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
+#endif /* #ifdef CONFIG_NO_HZ */
+ rdp->cpu = cpu;
+ spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+/*
+ * Initialize a CPU's per-CPU RCU data. Note that only one online or
+ * offline event can be happening at a given time. Note also that we
+ * can accept some slop in the rsp->completed access due to the fact
+ * that this CPU cannot possibly have any RCU callbacks in flight yet.
+ */
+static void __cpuinit
+rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
+{
+ unsigned long flags;
long lastcomp;
unsigned long mask;
struct rcu_data *rdp = rsp->rda[cpu];
@@ -1359,17 +1432,9 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->passed_quiesc = 0; /* We could be racing with new GP, */
rdp->qs_pending = 1; /* so set up to respond to current GP. */
rdp->beenonline = 1; /* We have now been online. */
+ rdp->preemptable = preemptable;
rdp->passed_quiesc_completed = lastcomp - 1;
- rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
- rdp->nxtlist = NULL;
- for (i = 0; i < RCU_NEXT_SIZE; i++)
- rdp->nxttail[i] = &rdp->nxtlist;
- rdp->qlen = 0;
rdp->blimit = blimit;
-#ifdef CONFIG_NO_HZ
- rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
-#endif /* #ifdef CONFIG_NO_HZ */
- rdp->cpu = cpu;
spin_unlock(&rnp->lock); /* irqs remain disabled. */
/*
@@ -1410,16 +1475,16 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
static void __cpuinit rcu_online_cpu(int cpu)
{
- rcu_init_percpu_data(cpu, &rcu_state);
- rcu_init_percpu_data(cpu, &rcu_bh_state);
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+ rcu_init_percpu_data(cpu, &rcu_sched_state, 0);
+ rcu_init_percpu_data(cpu, &rcu_bh_state, 0);
+ rcu_preempt_init_percpu_data(cpu);
}
/*
- * Handle CPU online/offline notifcation events.
+ * Handle CPU online/offline notification events.
*/
-static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
+int __cpuinit rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
@@ -1491,6 +1556,7 @@ static void __init rcu_init_one(struct rcu_state *rsp)
rnp = rsp->level[i];
for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
spin_lock_init(&rnp->lock);
+ rnp->gpnum = 0;
rnp->qsmask = 0;
rnp->qsmaskinit = 0;
rnp->grplo = j * cpustride;
@@ -1508,16 +1574,20 @@ static void __init rcu_init_one(struct rcu_state *rsp)
j / rsp->levelspread[i - 1];
}
rnp->level = i;
+ INIT_LIST_HEAD(&rnp->blocked_tasks[0]);
+ INIT_LIST_HEAD(&rnp->blocked_tasks[1]);
}
}
}
/*
- * Helper macro for __rcu_init(). To be used nowhere else!
- * Assigns leaf node pointers into each CPU's rcu_data structure.
+ * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used
+ * nowhere else! Assigns leaf node pointers into each CPU's rcu_data
+ * structure.
*/
-#define RCU_DATA_PTR_INIT(rsp, rcu_data) \
+#define RCU_INIT_FLAVOR(rsp, rcu_data) \
do { \
+ rcu_init_one(rsp); \
rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \
j = 0; \
for_each_possible_cpu(i) { \
@@ -1525,32 +1595,43 @@ do { \
j++; \
per_cpu(rcu_data, i).mynode = &rnp[j]; \
(rsp)->rda[i] = &per_cpu(rcu_data, i); \
+ rcu_boot_init_percpu_data(i, rsp); \
} \
} while (0)
-static struct notifier_block __cpuinitdata rcu_nb = {
- .notifier_call = rcu_cpu_notify,
-};
+#ifdef CONFIG_TREE_PREEMPT_RCU
+
+void __init __rcu_init_preempt(void)
+{
+ int i; /* All used by RCU_INIT_FLAVOR(). */
+ int j;
+ struct rcu_node *rnp;
+
+ RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data);
+}
+
+#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+
+void __init __rcu_init_preempt(void)
+{
+}
+
+#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
void __init __rcu_init(void)
{
- int i; /* All used by RCU_DATA_PTR_INIT(). */
+ int i; /* All used by RCU_INIT_FLAVOR(). */
int j;
struct rcu_node *rnp;
- printk(KERN_INFO "Hierarchical RCU implementation.\n");
+ rcu_bootup_announce();
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
- rcu_init_one(&rcu_state);
- RCU_DATA_PTR_INIT(&rcu_state, rcu_data);
- rcu_init_one(&rcu_bh_state);
- RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data);
-
- for_each_online_cpu(i)
- rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long)i);
- /* Register notifier for non-boot CPUs */
- register_cpu_notifier(&rcu_nb);
+ RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data);
+ RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data);
+ __rcu_init_preempt();
+ open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
}
module_param(blimit, int, 0);
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 5e872bbf07f5..bf8a6f9f134d 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -1,10 +1,259 @@
+/*
+ * Read-Copy Update mechanism for mutual exclusion (tree-based version)
+ * Internal non-public definitions.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2008
+ *
+ * Author: Ingo Molnar <mingo@elte.hu>
+ * Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ */
+
+#include <linux/cache.h>
+#include <linux/spinlock.h>
+#include <linux/threads.h>
+#include <linux/cpumask.h>
+#include <linux/seqlock.h>
+
+/*
+ * Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT.
+ * In theory, it should be possible to add more levels straightforwardly.
+ * In practice, this has not been tested, so there is probably some
+ * bug somewhere.
+ */
+#define MAX_RCU_LVLS 3
+#define RCU_FANOUT (CONFIG_RCU_FANOUT)
+#define RCU_FANOUT_SQ (RCU_FANOUT * RCU_FANOUT)
+#define RCU_FANOUT_CUBE (RCU_FANOUT_SQ * RCU_FANOUT)
+
+#if NR_CPUS <= RCU_FANOUT
+# define NUM_RCU_LVLS 1
+# define NUM_RCU_LVL_0 1
+# define NUM_RCU_LVL_1 (NR_CPUS)
+# define NUM_RCU_LVL_2 0
+# define NUM_RCU_LVL_3 0
+#elif NR_CPUS <= RCU_FANOUT_SQ
+# define NUM_RCU_LVLS 2
+# define NUM_RCU_LVL_0 1
+# define NUM_RCU_LVL_1 (((NR_CPUS) + RCU_FANOUT - 1) / RCU_FANOUT)
+# define NUM_RCU_LVL_2 (NR_CPUS)
+# define NUM_RCU_LVL_3 0
+#elif NR_CPUS <= RCU_FANOUT_CUBE
+# define NUM_RCU_LVLS 3
+# define NUM_RCU_LVL_0 1
+# define NUM_RCU_LVL_1 (((NR_CPUS) + RCU_FANOUT_SQ - 1) / RCU_FANOUT_SQ)
+# define NUM_RCU_LVL_2 (((NR_CPUS) + (RCU_FANOUT) - 1) / (RCU_FANOUT))
+# define NUM_RCU_LVL_3 NR_CPUS
+#else
+# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
+#endif /* #if (NR_CPUS) <= RCU_FANOUT */
+
+#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3)
+#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
+
+/*
+ * Dynticks per-CPU state.
+ */
+struct rcu_dynticks {
+ int dynticks_nesting; /* Track nesting level, sort of. */
+ int dynticks; /* Even value for dynticks-idle, else odd. */
+ int dynticks_nmi; /* Even value for either dynticks-idle or */
+ /* not in nmi handler, else odd. So this */
+ /* remains even for nmi from irq handler. */
+};
+
+/*
+ * Definition for node within the RCU grace-period-detection hierarchy.
+ */
+struct rcu_node {
+ spinlock_t lock;
+ long gpnum; /* Current grace period for this node. */
+ /* This will either be equal to or one */
+ /* behind the root rcu_node's gpnum. */
+ unsigned long qsmask; /* CPUs or groups that need to switch in */
+ /* order for current grace period to proceed.*/
+ unsigned long qsmaskinit;
+ /* Per-GP initialization for qsmask. */
+ unsigned long grpmask; /* Mask to apply to parent qsmask. */
+ int grplo; /* lowest-numbered CPU or group here. */
+ int grphi; /* highest-numbered CPU or group here. */
+ u8 grpnum; /* CPU/group number for next level up. */
+ u8 level; /* root is at level 0. */
+ struct rcu_node *parent;
+ struct list_head blocked_tasks[2];
+ /* Tasks blocked in RCU read-side critsect. */
+} ____cacheline_internodealigned_in_smp;
+
+/* Index values for nxttail array in struct rcu_data. */
+#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
+#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
+#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
+#define RCU_NEXT_TAIL 3
+#define RCU_NEXT_SIZE 4
+
+/* Per-CPU data for read-copy update. */
+struct rcu_data {
+ /* 1) quiescent-state and grace-period handling : */
+ long completed; /* Track rsp->completed gp number */
+ /* in order to detect GP end. */
+ long gpnum; /* Highest gp number that this CPU */
+ /* is aware of having started. */
+ long passed_quiesc_completed;
+ /* Value of completed at time of qs. */
+ bool passed_quiesc; /* User-mode/idle loop etc. */
+ bool qs_pending; /* Core waits for quiesc state. */
+ bool beenonline; /* CPU online at least once. */
+ bool preemptable; /* Preemptable RCU? */
+ struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
+ unsigned long grpmask; /* Mask to apply to leaf qsmask. */
+
+ /* 2) batch handling */
+ /*
+ * If nxtlist is not NULL, it is partitioned as follows.
+ * Any of the partitions might be empty, in which case the
+ * pointer to that partition will be equal to the pointer for
+ * the following partition. When the list is empty, all of
+ * the nxttail elements point to nxtlist, which is NULL.
+ *
+ * [*nxttail[RCU_NEXT_READY_TAIL], NULL = *nxttail[RCU_NEXT_TAIL]):
+ * Entries that might have arrived after current GP ended
+ * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
+ * Entries known to have arrived before current GP ended
+ * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
+ * Entries that batch # <= ->completed - 1: waiting for current GP
+ * [nxtlist, *nxttail[RCU_DONE_TAIL]):
+ * Entries that batch # <= ->completed
+ * The grace period for these entries has completed, and
+ * the other grace-period-completed entries may be moved
+ * here temporarily in rcu_process_callbacks().
+ */
+ struct rcu_head *nxtlist;
+ struct rcu_head **nxttail[RCU_NEXT_SIZE];
+ long qlen; /* # of queued callbacks */
+ long blimit; /* Upper limit on a processed batch */
+
+#ifdef CONFIG_NO_HZ
+ /* 3) dynticks interface. */
+ struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
+ int dynticks_snap; /* Per-GP tracking for dynticks. */
+ int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */
+#endif /* #ifdef CONFIG_NO_HZ */
+
+ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
+#ifdef CONFIG_NO_HZ
+ unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
+#endif /* #ifdef CONFIG_NO_HZ */
+ unsigned long offline_fqs; /* Kicked due to being offline. */
+ unsigned long resched_ipi; /* Sent a resched IPI. */
+
+ /* 5) __rcu_pending() statistics. */
+ long n_rcu_pending; /* rcu_pending() calls since boot. */
+ long n_rp_qs_pending;
+ long n_rp_cb_ready;
+ long n_rp_cpu_needs_gp;
+ long n_rp_gp_completed;
+ long n_rp_gp_started;
+ long n_rp_need_fqs;
+ long n_rp_need_nothing;
+
+ int cpu;
+};
+
+/* Values for signaled field in struct rcu_state. */
+#define RCU_GP_INIT 0 /* Grace period being initialized. */
+#define RCU_SAVE_DYNTICK 1 /* Need to scan dyntick state. */
+#define RCU_FORCE_QS 2 /* Need to force quiescent state. */
+#ifdef CONFIG_NO_HZ
+#define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
+#else /* #ifdef CONFIG_NO_HZ */
+#define RCU_SIGNAL_INIT RCU_FORCE_QS
+#endif /* #else #ifdef CONFIG_NO_HZ */
+
+#define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+#define RCU_SECONDS_TILL_STALL_CHECK (10 * HZ) /* for rsp->jiffies_stall */
+#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rsp->jiffies_stall */
+#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */
+ /* to take at least one */
+ /* scheduling clock irq */
+ /* before ratting on them. */
+
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+
+/*
+ * RCU global state, including node hierarchy. This hierarchy is
+ * represented in "heap" form in a dense array. The root (first level)
+ * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
+ * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
+ * and the third level in ->node[m+1] and following (->node[m+1] referenced
+ * by ->level[2]). The number of levels is determined by the number of
+ * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
+ * consisting of a single rcu_node.
+ */
+struct rcu_state {
+ struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
+ struct rcu_node *level[NUM_RCU_LVLS]; /* Hierarchy levels. */
+ u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
+ u8 levelspread[NUM_RCU_LVLS]; /* kids/node in each level. */
+ struct rcu_data *rda[NR_CPUS]; /* array of rdp pointers. */
+
+ /* The following fields are guarded by the root rcu_node's lock. */
+
+ u8 signaled ____cacheline_internodealigned_in_smp;
+ /* Force QS state. */
+ long gpnum; /* Current gp number. */
+ long completed; /* # of last completed gp. */
+ spinlock_t onofflock; /* exclude on/offline and */
+ /* starting new GP. */
+ spinlock_t fqslock; /* Only one task forcing */
+ /* quiescent states. */
+ unsigned long jiffies_force_qs; /* Time at which to invoke */
+ /* force_quiescent_state(). */
+ unsigned long n_force_qs; /* Number of calls to */
+ /* force_quiescent_state(). */
+ unsigned long n_force_qs_lh; /* ~Number of calls leaving */
+ /* due to lock unavailable. */
+ unsigned long n_force_qs_ngp; /* Number of calls leaving */
+ /* due to no GP active. */
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+ unsigned long gp_start; /* Time at which GP started, */
+ /* but in jiffies. */
+ unsigned long jiffies_stall; /* Time at which to check */
+ /* for CPU stalls. */
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+#ifdef CONFIG_NO_HZ
+ long dynticks_completed; /* Value of completed @ snap. */
+#endif /* #ifdef CONFIG_NO_HZ */
+};
+
+#ifdef RCU_TREE_NONCORE
/*
* RCU implementation internal declarations:
*/
-extern struct rcu_state rcu_state;
-DECLARE_PER_CPU(struct rcu_data, rcu_data);
+extern struct rcu_state rcu_sched_state;
+DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
extern struct rcu_state rcu_bh_state;
DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
+#ifdef CONFIG_TREE_PREEMPT_RCU
+extern struct rcu_state rcu_preempt_state;
+DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+
+#endif /* #ifdef RCU_TREE_NONCORE */
+
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
new file mode 100644
index 000000000000..47789369ea59
--- /dev/null
+++ b/kernel/rcutree_plugin.h
@@ -0,0 +1,532 @@
+/*
+ * Read-Copy Update mechanism for mutual exclusion (tree-based version)
+ * Internal non-public definitions that provide either classic
+ * or preemptable semantics.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright Red Hat, 2009
+ * Copyright IBM Corporation, 2009
+ *
+ * Author: Ingo Molnar <mingo@elte.hu>
+ * Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ */
+
+
+#ifdef CONFIG_TREE_PREEMPT_RCU
+
+struct rcu_state rcu_preempt_state = RCU_STATE_INITIALIZER(rcu_preempt_state);
+DEFINE_PER_CPU(struct rcu_data, rcu_preempt_data);
+
+/*
+ * Tell them what RCU they are running.
+ */
+static inline void rcu_bootup_announce(void)
+{
+ printk(KERN_INFO
+ "Experimental preemptable hierarchical RCU implementation.\n");
+}
+
+/*
+ * Return the number of RCU-preempt batches processed thus far
+ * for debug and statistics.
+ */
+long rcu_batches_completed_preempt(void)
+{
+ return rcu_preempt_state.completed;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_completed_preempt);
+
+/*
+ * Return the number of RCU batches processed thus far for debug & stats.
+ */
+long rcu_batches_completed(void)
+{
+ return rcu_batches_completed_preempt();
+}
+EXPORT_SYMBOL_GPL(rcu_batches_completed);
+
+/*
+ * Record a preemptable-RCU quiescent state for the specified CPU. Note
+ * that this just means that the task currently running on the CPU is
+ * not in a quiescent state. There might be any number of tasks blocked
+ * while in an RCU read-side critical section.
+ */
+static void rcu_preempt_qs_record(int cpu)
+{
+ struct rcu_data *rdp = &per_cpu(rcu_preempt_data, cpu);
+ rdp->passed_quiesc = 1;
+ rdp->passed_quiesc_completed = rdp->completed;
+}
+
+/*
+ * We have entered the scheduler or are between softirqs in ksoftirqd.
+ * If we are in an RCU read-side critical section, we need to reflect
+ * that in the state of the rcu_node structure corresponding to this CPU.
+ * Caller must disable hardirqs.
+ */
+static void rcu_preempt_qs(int cpu)
+{
+ struct task_struct *t = current;
+ int phase;
+ struct rcu_data *rdp;
+ struct rcu_node *rnp;
+
+ if (t->rcu_read_lock_nesting &&
+ (t->rcu_read_unlock_special & RCU_READ_UNLOCK_BLOCKED) == 0) {
+
+ /* Possibly blocking in an RCU read-side critical section. */
+ rdp = rcu_preempt_state.rda[cpu];
+ rnp = rdp->mynode;
+ spin_lock(&rnp->lock);
+ t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
+ t->rcu_blocked_node = rnp;
+
+ /*
+ * If this CPU has already checked in, then this task
+ * will hold up the next grace period rather than the
+ * current grace period. Queue the task accordingly.
+ * If the task is queued for the current grace period
+ * (i.e., this CPU has not yet passed through a quiescent
+ * state for the current grace period), then as long
+ * as that task remains queued, the current grace period
+ * cannot end.
+ */
+ phase = !(rnp->qsmask & rdp->grpmask) ^ (rnp->gpnum & 0x1);
+ list_add(&t->rcu_node_entry, &rnp->blocked_tasks[phase]);
+ smp_mb(); /* Ensure later ctxt swtch seen after above. */
+ spin_unlock(&rnp->lock);
+ }
+
+ /*
+ * Either we were not in an RCU read-side critical section to
+ * begin with, or we have now recorded that critical section
+ * globally. Either way, we can now note a quiescent state
+ * for this CPU. Again, if we were in an RCU read-side critical
+ * section, and if that critical section was blocking the current
+ * grace period, then the fact that the task has been enqueued
+ * means that we continue to block the current grace period.
+ */
+ rcu_preempt_qs_record(cpu);
+ t->rcu_read_unlock_special &= ~(RCU_READ_UNLOCK_NEED_QS |
+ RCU_READ_UNLOCK_GOT_QS);
+}
+
+/*
+ * Tree-preemptable RCU implementation for rcu_read_lock().
+ * Just increment ->rcu_read_lock_nesting, shared state will be updated
+ * if we block.
+ */
+void __rcu_read_lock(void)
+{
+ ACCESS_ONCE(current->rcu_read_lock_nesting)++;
+ barrier(); /* needed if we ever invoke rcu_read_lock in rcutree.c */
+}
+EXPORT_SYMBOL_GPL(__rcu_read_lock);
+
+static void rcu_read_unlock_special(struct task_struct *t)
+{
+ int empty;
+ unsigned long flags;
+ unsigned long mask;
+ struct rcu_node *rnp;
+ int special;
+
+ /* NMI handlers cannot block and cannot safely manipulate state. */
+ if (in_nmi())
+ return;
+
+ local_irq_save(flags);
+
+ /*
+ * If RCU core is waiting for this CPU to exit critical section,
+ * let it know that we have done so.
+ */
+ special = t->rcu_read_unlock_special;
+ if (special & RCU_READ_UNLOCK_NEED_QS) {
+ t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_NEED_QS;
+ t->rcu_read_unlock_special |= RCU_READ_UNLOCK_GOT_QS;
+ }
+
+ /* Hardware IRQ handlers cannot block. */
+ if (in_irq()) {
+ local_irq_restore(flags);
+ return;
+ }
+
+ /* Clean up if blocked during RCU read-side critical section. */
+ if (special & RCU_READ_UNLOCK_BLOCKED) {
+ t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_BLOCKED;
+
+ /*
+ * Remove this task from the list it blocked on. The
+ * task can migrate while we acquire the lock, but at
+ * most one time. So at most two passes through loop.
+ */
+ for (;;) {
+ rnp = t->rcu_blocked_node;
+ spin_lock(&rnp->lock);
+ if (rnp == t->rcu_blocked_node)
+ break;
+ spin_unlock(&rnp->lock);
+ }
+ empty = list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]);
+ list_del_init(&t->rcu_node_entry);
+ t->rcu_blocked_node = NULL;
+
+ /*
+ * If this was the last task on the current list, and if
+ * we aren't waiting on any CPUs, report the quiescent state.
+ * Note that both cpu_quiet_msk_finish() and cpu_quiet_msk()
+ * drop rnp->lock and restore irq.
+ */
+ if (!empty && rnp->qsmask == 0 &&
+ list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1])) {
+ t->rcu_read_unlock_special &=
+ ~(RCU_READ_UNLOCK_NEED_QS |
+ RCU_READ_UNLOCK_GOT_QS);
+ if (rnp->parent == NULL) {
+ /* Only one rcu_node in the tree. */
+ cpu_quiet_msk_finish(&rcu_preempt_state, flags);
+ return;
+ }
+ /* Report up the rest of the hierarchy. */
+ mask = rnp->grpmask;
+ spin_unlock_irqrestore(&rnp->lock, flags);
+ rnp = rnp->parent;
+ spin_lock_irqsave(&rnp->lock, flags);
+ cpu_quiet_msk(mask, &rcu_preempt_state, rnp, flags);
+ return;
+ }
+ spin_unlock(&rnp->lock);
+ }
+ local_irq_restore(flags);
+}
+
+/*
+ * Tree-preemptable RCU implementation for rcu_read_unlock().
+ * Decrement ->rcu_read_lock_nesting. If the result is zero (outermost
+ * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then
+ * invoke rcu_read_unlock_special() to clean up after a context switch
+ * in an RCU read-side critical section and other special cases.
+ */
+void __rcu_read_unlock(void)
+{
+ struct task_struct *t = current;
+
+ barrier(); /* needed if we ever invoke rcu_read_unlock in rcutree.c */
+ if (--ACCESS_ONCE(t->rcu_read_lock_nesting) == 0 &&
+ unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
+ rcu_read_unlock_special(t);
+}
+EXPORT_SYMBOL_GPL(__rcu_read_unlock);
+
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+
+/*
+ * Scan the current list of tasks blocked within RCU read-side critical
+ * sections, printing out the tid of each.
+ */
+static void rcu_print_task_stall(struct rcu_node *rnp)
+{
+ unsigned long flags;
+ struct list_head *lp;
+ int phase = rnp->gpnum & 0x1;
+ struct task_struct *t;
+
+ if (!list_empty(&rnp->blocked_tasks[phase])) {
+ spin_lock_irqsave(&rnp->lock, flags);
+ phase = rnp->gpnum & 0x1; /* re-read under lock. */
+ lp = &rnp->blocked_tasks[phase];
+ list_for_each_entry(t, lp, rcu_node_entry)
+ printk(" P%d", t->pid);
+ spin_unlock_irqrestore(&rnp->lock, flags);
+ }
+}
+
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+
+/*
+ * Check for preempted RCU readers for the specified rcu_node structure.
+ * If the caller needs a reliable answer, it must hold the rcu_node's
+ * >lock.
+ */
+static int rcu_preempted_readers(struct rcu_node *rnp)
+{
+ return !list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/*
+ * Handle tasklist migration for case in which all CPUs covered by the
+ * specified rcu_node have gone offline. Move them up to the root
+ * rcu_node. The reason for not just moving them to the immediate
+ * parent is to remove the need for rcu_read_unlock_special() to
+ * make more than two attempts to acquire the target rcu_node's lock.
+ *
+ * The caller must hold rnp->lock with irqs disabled.
+ */
+static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
+ struct rcu_node *rnp)
+{
+ int i;
+ struct list_head *lp;
+ struct list_head *lp_root;
+ struct rcu_node *rnp_root = rcu_get_root(rsp);
+ struct task_struct *tp;
+
+ if (rnp == rnp_root) {
+ WARN_ONCE(1, "Last CPU thought to be offlined?");
+ return; /* Shouldn't happen: at least one CPU online. */
+ }
+
+ /*
+ * Move tasks up to root rcu_node. Rely on the fact that the
+ * root rcu_node can be at most one ahead of the rest of the
+ * rcu_nodes in terms of gp_num value. This fact allows us to
+ * move the blocked_tasks[] array directly, element by element.
+ */
+ for (i = 0; i < 2; i++) {
+ lp = &rnp->blocked_tasks[i];
+ lp_root = &rnp_root->blocked_tasks[i];
+ while (!list_empty(lp)) {
+ tp = list_entry(lp->next, typeof(*tp), rcu_node_entry);
+ spin_lock(&rnp_root->lock); /* irqs already disabled */
+ list_del(&tp->rcu_node_entry);
+ tp->rcu_blocked_node = rnp_root;
+ list_add(&tp->rcu_node_entry, lp_root);
+ spin_unlock(&rnp_root->lock); /* irqs remain disabled */
+ }
+ }
+}
+
+/*
+ * Do CPU-offline processing for preemptable RCU.
+ */
+static void rcu_preempt_offline_cpu(int cpu)
+{
+ __rcu_offline_cpu(cpu, &rcu_preempt_state);
+}
+
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+
+/*
+ * Check for a quiescent state from the current CPU. When a task blocks,
+ * the task is recorded in the corresponding CPU's rcu_node structure,
+ * which is checked elsewhere.
+ *
+ * Caller must disable hard irqs.
+ */
+static void rcu_preempt_check_callbacks(int cpu)
+{
+ struct task_struct *t = current;
+
+ if (t->rcu_read_lock_nesting == 0) {
+ t->rcu_read_unlock_special &=
+ ~(RCU_READ_UNLOCK_NEED_QS | RCU_READ_UNLOCK_GOT_QS);
+ rcu_preempt_qs_record(cpu);
+ return;
+ }
+ if (per_cpu(rcu_preempt_data, cpu).qs_pending) {
+ if (t->rcu_read_unlock_special & RCU_READ_UNLOCK_GOT_QS) {
+ rcu_preempt_qs_record(cpu);
+ t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_GOT_QS;
+ } else if (!(t->rcu_read_unlock_special &
+ RCU_READ_UNLOCK_NEED_QS)) {
+ t->rcu_read_unlock_special |= RCU_READ_UNLOCK_NEED_QS;
+ }
+ }
+}
+
+/*
+ * Process callbacks for preemptable RCU.
+ */
+static void rcu_preempt_process_callbacks(void)
+{
+ __rcu_process_callbacks(&rcu_preempt_state,
+ &__get_cpu_var(rcu_preempt_data));
+}
+
+/*
+ * Queue a preemptable-RCU callback for invocation after a grace period.
+ */
+void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+{
+ __call_rcu(head, func, &rcu_preempt_state);
+}
+EXPORT_SYMBOL_GPL(call_rcu);
+
+/*
+ * Check to see if there is any immediate preemptable-RCU-related work
+ * to be done.
+ */
+static int rcu_preempt_pending(int cpu)
+{
+ return __rcu_pending(&rcu_preempt_state,
+ &per_cpu(rcu_preempt_data, cpu));
+}
+
+/*
+ * Does preemptable RCU need the CPU to stay out of dynticks mode?
+ */
+static int rcu_preempt_needs_cpu(int cpu)
+{
+ return !!per_cpu(rcu_preempt_data, cpu).nxtlist;
+}
+
+/*
+ * Initialize preemptable RCU's per-CPU data.
+ */
+static void __cpuinit rcu_preempt_init_percpu_data(int cpu)
+{
+ rcu_init_percpu_data(cpu, &rcu_preempt_state, 1);
+}
+
+/*
+ * Check for a task exiting while in a preemptable-RCU read-side
+ * critical section, clean up if so. No need to issue warnings,
+ * as debug_check_no_locks_held() already does this if lockdep
+ * is enabled.
+ */
+void exit_rcu(void)
+{
+ struct task_struct *t = current;
+
+ if (t->rcu_read_lock_nesting == 0)
+ return;
+ t->rcu_read_lock_nesting = 1;
+ rcu_read_unlock();
+}
+
+#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+
+/*
+ * Tell them what RCU they are running.
+ */
+static inline void rcu_bootup_announce(void)
+{
+ printk(KERN_INFO "Hierarchical RCU implementation.\n");
+}
+
+/*
+ * Return the number of RCU batches processed thus far for debug & stats.
+ */
+long rcu_batches_completed(void)
+{
+ return rcu_batches_completed_sched();
+}
+EXPORT_SYMBOL_GPL(rcu_batches_completed);
+
+/*
+ * Because preemptable RCU does not exist, we never have to check for
+ * CPUs being in quiescent states.
+ */
+static void rcu_preempt_qs(int cpu)
+{
+}
+
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+
+/*
+ * Because preemptable RCU does not exist, we never have to check for
+ * tasks blocked within RCU read-side critical sections.
+ */
+static void rcu_print_task_stall(struct rcu_node *rnp)
+{
+}
+
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+
+/*
+ * Because preemptable RCU does not exist, there are never any preempted
+ * RCU readers.
+ */
+static int rcu_preempted_readers(struct rcu_node *rnp)
+{
+ return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/*
+ * Because preemptable RCU does not exist, it never needs to migrate
+ * tasks that were blocked within RCU read-side critical sections.
+ */
+static void rcu_preempt_offline_tasks(struct rcu_state *rsp,
+ struct rcu_node *rnp)
+{
+}
+
+/*
+ * Because preemptable RCU does not exist, it never needs CPU-offline
+ * processing.
+ */
+static void rcu_preempt_offline_cpu(int cpu)
+{
+}
+
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+
+/*
+ * Because preemptable RCU does not exist, it never has any callbacks
+ * to check.
+ */
+void rcu_preempt_check_callbacks(int cpu)
+{
+}
+
+/*
+ * Because preemptable RCU does not exist, it never has any callbacks
+ * to process.
+ */
+void rcu_preempt_process_callbacks(void)
+{
+}
+
+/*
+ * In classic RCU, call_rcu() is just call_rcu_sched().
+ */
+void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+{
+ call_rcu_sched(head, func);
+}
+EXPORT_SYMBOL_GPL(call_rcu);
+
+/*
+ * Because preemptable RCU does not exist, it never has any work to do.
+ */
+static int rcu_preempt_pending(int cpu)
+{
+ return 0;
+}
+
+/*
+ * Because preemptable RCU does not exist, it never needs any CPU.
+ */
+static int rcu_preempt_needs_cpu(int cpu)
+{
+ return 0;
+}
+
+/*
+ * Because preemptable RCU does not exist, there is no per-CPU
+ * data to initialize.
+ */
+static void __cpuinit rcu_preempt_init_percpu_data(int cpu)
+{
+}
+
+#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index fe1dcdbf1ca3..0ea1bff69727 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -43,6 +43,7 @@
#include <linux/debugfs.h>
#include <linux/seq_file.h>
+#define RCU_TREE_NONCORE
#include "rcutree.h"
static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
@@ -76,8 +77,12 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
static int show_rcudata(struct seq_file *m, void *unused)
{
- seq_puts(m, "rcu:\n");
- PRINT_RCU_DATA(rcu_data, print_one_rcu_data, m);
+#ifdef CONFIG_TREE_PREEMPT_RCU
+ seq_puts(m, "rcu_preempt:\n");
+ PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data, m);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+ seq_puts(m, "rcu_sched:\n");
+ PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
seq_puts(m, "rcu_bh:\n");
PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
return 0;
@@ -102,7 +107,7 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
return;
seq_printf(m, "%d,%s,%ld,%ld,%d,%ld,%d",
rdp->cpu,
- cpu_is_offline(rdp->cpu) ? "\"Y\"" : "\"N\"",
+ cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
rdp->completed, rdp->gpnum,
rdp->passed_quiesc, rdp->passed_quiesc_completed,
rdp->qs_pending);
@@ -124,8 +129,12 @@ static int show_rcudata_csv(struct seq_file *m, void *unused)
seq_puts(m, "\"dt\",\"dt nesting\",\"dn\",\"df\",");
#endif /* #ifdef CONFIG_NO_HZ */
seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\"\n");
- seq_puts(m, "\"rcu:\"\n");
- PRINT_RCU_DATA(rcu_data, print_one_rcu_data_csv, m);
+#ifdef CONFIG_TREE_PREEMPT_RCU
+ seq_puts(m, "\"rcu_preempt:\"\n");
+ PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+ seq_puts(m, "\"rcu_sched:\"\n");
+ PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
seq_puts(m, "\"rcu_bh:\"\n");
PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
return 0;
@@ -171,8 +180,12 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
static int show_rcuhier(struct seq_file *m, void *unused)
{
- seq_puts(m, "rcu:\n");
- print_one_rcu_state(m, &rcu_state);
+#ifdef CONFIG_TREE_PREEMPT_RCU
+ seq_puts(m, "rcu_preempt:\n");
+ print_one_rcu_state(m, &rcu_preempt_state);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+ seq_puts(m, "rcu_sched:\n");
+ print_one_rcu_state(m, &rcu_sched_state);
seq_puts(m, "rcu_bh:\n");
print_one_rcu_state(m, &rcu_bh_state);
return 0;
@@ -193,8 +206,12 @@ static struct file_operations rcuhier_fops = {
static int show_rcugp(struct seq_file *m, void *unused)
{
- seq_printf(m, "rcu: completed=%ld gpnum=%ld\n",
- rcu_state.completed, rcu_state.gpnum);
+#ifdef CONFIG_TREE_PREEMPT_RCU
+ seq_printf(m, "rcu_preempt: completed=%ld gpnum=%ld\n",
+ rcu_preempt_state.completed, rcu_preempt_state.gpnum);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+ seq_printf(m, "rcu_sched: completed=%ld gpnum=%ld\n",
+ rcu_sched_state.completed, rcu_sched_state.gpnum);
seq_printf(m, "rcu_bh: completed=%ld gpnum=%ld\n",
rcu_bh_state.completed, rcu_bh_state.gpnum);
return 0;
@@ -243,8 +260,12 @@ static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
static int show_rcu_pending(struct seq_file *m, void *unused)
{
- seq_puts(m, "rcu:\n");
- print_rcu_pendings(m, &rcu_state);
+#ifdef CONFIG_TREE_PREEMPT_RCU
+ seq_puts(m, "rcu_preempt:\n");
+ print_rcu_pendings(m, &rcu_preempt_state);
+#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+ seq_puts(m, "rcu_sched:\n");
+ print_rcu_pendings(m, &rcu_sched_state);
seq_puts(m, "rcu_bh:\n");
print_rcu_pendings(m, &rcu_bh_state);
return 0;
@@ -264,62 +285,47 @@ static struct file_operations rcu_pending_fops = {
};
static struct dentry *rcudir;
-static struct dentry *datadir;
-static struct dentry *datadir_csv;
-static struct dentry *gpdir;
-static struct dentry *hierdir;
-static struct dentry *rcu_pendingdir;
static int __init rcuclassic_trace_init(void)
{
+ struct dentry *retval;
+
rcudir = debugfs_create_dir("rcu", NULL);
if (!rcudir)
- goto out;
+ goto free_out;
- datadir = debugfs_create_file("rcudata", 0444, rcudir,
+ retval = debugfs_create_file("rcudata", 0444, rcudir,
NULL, &rcudata_fops);
- if (!datadir)
+ if (!retval)
goto free_out;
- datadir_csv = debugfs_create_file("rcudata.csv", 0444, rcudir,
+ retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
NULL, &rcudata_csv_fops);
- if (!datadir_csv)
+ if (!retval)
goto free_out;
- gpdir = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
- if (!gpdir)
+ retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
+ if (!retval)
goto free_out;
- hierdir = debugfs_create_file("rcuhier", 0444, rcudir,
+ retval = debugfs_create_file("rcuhier", 0444, rcudir,
NULL, &rcuhier_fops);
- if (!hierdir)
+ if (!retval)
goto free_out;
- rcu_pendingdir = debugfs_create_file("rcu_pending", 0444, rcudir,
+ retval = debugfs_create_file("rcu_pending", 0444, rcudir,
NULL, &rcu_pending_fops);
- if (!rcu_pendingdir)
+ if (!retval)
goto free_out;
return 0;
free_out:
- if (datadir)
- debugfs_remove(datadir);
- if (datadir_csv)
- debugfs_remove(datadir_csv);
- if (gpdir)
- debugfs_remove(gpdir);
- debugfs_remove(rcudir);
-out:
+ debugfs_remove_recursive(rcudir);
return 1;
}
static void __exit rcuclassic_trace_cleanup(void)
{
- debugfs_remove(datadir);
- debugfs_remove(datadir_csv);
- debugfs_remove(gpdir);
- debugfs_remove(hierdir);
- debugfs_remove(rcu_pendingdir);
- debugfs_remove(rcudir);
+ debugfs_remove_recursive(rcudir);
}
diff --git a/kernel/sched.c b/kernel/sched.c
index 2c75f7daa439..4066241ae9f4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5325,7 +5325,7 @@ need_resched:
preempt_disable();
cpu = smp_processor_id();
rq = cpu_rq(cpu);
- rcu_qsctr_inc(cpu);
+ rcu_sched_qs(cpu);
prev = rq->curr;
switch_count = &prev->nivcsw;
@@ -7053,6 +7053,11 @@ fail:
return ret;
}
+#define RCU_MIGRATION_IDLE 0
+#define RCU_MIGRATION_NEED_QS 1
+#define RCU_MIGRATION_GOT_QS 2
+#define RCU_MIGRATION_MUST_SYNC 3
+
/*
* migration_thread - this is a highprio system thread that performs
* thread migration by bumping thread off CPU then 'pushing' onto
@@ -7060,6 +7065,7 @@ fail:
*/
static int migration_thread(void *data)
{
+ int badcpu;
int cpu = (long)data;
struct rq *rq;
@@ -7094,8 +7100,17 @@ static int migration_thread(void *data)
req = list_entry(head->next, struct migration_req, list);
list_del_init(head->next);
- spin_unlock(&rq->lock);
- __migrate_task(req->task, cpu, req->dest_cpu);
+ if (req->task != NULL) {
+ spin_unlock(&rq->lock);
+ __migrate_task(req->task, cpu, req->dest_cpu);
+ } else if (likely(cpu == (badcpu = smp_processor_id()))) {
+ req->dest_cpu = RCU_MIGRATION_GOT_QS;
+ spin_unlock(&rq->lock);
+ } else {
+ req->dest_cpu = RCU_MIGRATION_MUST_SYNC;
+ spin_unlock(&rq->lock);
+ WARN_ONCE(1, "migration_thread() on CPU %d, expected %d\n", badcpu, cpu);
+ }
local_irq_enable();
complete(&req->done);
@@ -10583,3 +10598,113 @@ struct cgroup_subsys cpuacct_subsys = {
.subsys_id = cpuacct_subsys_id,
};
#endif /* CONFIG_CGROUP_CPUACCT */
+
+#ifndef CONFIG_SMP
+
+int rcu_expedited_torture_stats(char *page)
+{
+ return 0;
+}
+EXPORT_SYMBOL_GPL(rcu_expedited_torture_stats);
+
+void synchronize_sched_expedited(void)
+{
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#else /* #ifndef CONFIG_SMP */
+
+static DEFINE_PER_CPU(struct migration_req, rcu_migration_req);
+static DEFINE_MUTEX(rcu_sched_expedited_mutex);
+
+#define RCU_EXPEDITED_STATE_POST -2
+#define RCU_EXPEDITED_STATE_IDLE -1
+
+static int rcu_expedited_state = RCU_EXPEDITED_STATE_IDLE;
+
+int rcu_expedited_torture_stats(char *page)
+{
+ int cnt = 0;
+ int cpu;
+
+ cnt += sprintf(&page[cnt], "state: %d /", rcu_expedited_state);
+ for_each_online_cpu(cpu) {
+ cnt += sprintf(&page[cnt], " %d:%d",
+ cpu, per_cpu(rcu_migration_req, cpu).dest_cpu);
+ }
+ cnt += sprintf(&page[cnt], "\n");
+ return cnt;
+}
+EXPORT_SYMBOL_GPL(rcu_expedited_torture_stats);
+
+static long synchronize_sched_expedited_count;
+
+/*
+ * Wait for an rcu-sched grace period to elapse, but use "big hammer"
+ * approach to force grace period to end quickly. This consumes
+ * significant time on all CPUs, and is thus not recommended for
+ * any sort of common-case code.
+ *
+ * Note that it is illegal to call this function while holding any
+ * lock that is acquired by a CPU-hotplug notifier. Failing to
+ * observe this restriction will result in deadlock.
+ */
+void synchronize_sched_expedited(void)
+{
+ int cpu;
+ unsigned long flags;
+ bool need_full_sync = 0;
+ struct rq *rq;
+ struct migration_req *req;
+ long snap;
+ int trycount = 0;
+
+ smp_mb(); /* ensure prior mod happens before capturing snap. */
+ snap = ACCESS_ONCE(synchronize_sched_expedited_count) + 1;
+ get_online_cpus();
+ while (!mutex_trylock(&rcu_sched_expedited_mutex)) {
+ put_online_cpus();
+ if (trycount++ < 10)
+ udelay(trycount * num_online_cpus());
+ else {
+ synchronize_sched();
+ return;
+ }
+ if (ACCESS_ONCE(synchronize_sched_expedited_count) - snap > 0) {
+ smp_mb(); /* ensure test happens before caller kfree */
+ return;
+ }
+ get_online_cpus();
+ }
+ rcu_expedited_state = RCU_EXPEDITED_STATE_POST;
+ for_each_online_cpu(cpu) {
+ rq = cpu_rq(cpu);
+ req = &per_cpu(rcu_migration_req, cpu);
+ init_completion(&req->done);
+ req->task = NULL;
+ req->dest_cpu = RCU_MIGRATION_NEED_QS;
+ spin_lock_irqsave(&rq->lock, flags);
+ list_add(&req->list, &rq->migration_queue);
+ spin_unlock_irqrestore(&rq->lock, flags);
+ wake_up_process(rq->migration_thread);
+ }
+ for_each_online_cpu(cpu) {
+ rcu_expedited_state = cpu;
+ req = &per_cpu(rcu_migration_req, cpu);
+ rq = cpu_rq(cpu);
+ wait_for_completion(&req->done);
+ spin_lock_irqsave(&rq->lock, flags);
+ if (unlikely(req->dest_cpu == RCU_MIGRATION_MUST_SYNC))
+ need_full_sync = 1;
+ req->dest_cpu = RCU_MIGRATION_IDLE;
+ spin_unlock_irqrestore(&rq->lock, flags);
+ }
+ rcu_expedited_state = RCU_EXPEDITED_STATE_IDLE;
+ mutex_unlock(&rcu_sched_expedited_mutex);
+ put_online_cpus();
+ if (need_full_sync)
+ synchronize_sched();
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#endif /* #else #ifndef CONFIG_SMP */
diff --git a/kernel/softirq.c b/kernel/softirq.c
index eb5e131a0485..7db25067cd2d 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -227,7 +227,7 @@ restart:
preempt_count() = prev_count;
}
- rcu_bh_qsctr_inc(cpu);
+ rcu_bh_qs(cpu);
}
h++;
pending >>= 1;
@@ -721,7 +721,7 @@ static int ksoftirqd(void * __bind_cpu)
preempt_enable_no_resched();
cond_resched();
preempt_disable();
- rcu_qsctr_inc((long)__bind_cpu);
+ rcu_sched_qs((long)__bind_cpu);
}
preempt_enable();
set_current_state(TASK_INTERRUPTIBLE);
diff --git a/kernel/timer.c b/kernel/timer.c
index a7f07d5a6241..a3d25f415019 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1156,8 +1156,7 @@ void update_process_times(int user_tick)
/* Note: this timer irq context must be accounted for as well. */
account_process_tick(p, user_tick);
run_local_timers();
- if (rcu_pending(cpu))
- rcu_check_callbacks(cpu, user_tick);
+ rcu_check_callbacks(cpu, user_tick);
printk_tick();
scheduler_tick();
run_posix_cpu_timers(p);