summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--fs/proc/stat.c2
-rw-r--r--include/linux/kernel_stat.h1
-rw-r--r--kernel/irq/internals.h8
-rw-r--r--kernel/irq/irqdesc.c52
-rw-r--r--kernel/irq/proc.c22
5 files changed, 83 insertions, 2 deletions
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 1cf86c0e8689..b5c72a3be359 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -159,7 +159,7 @@ static int show_stat(struct seq_file *p, void *v)
/* sum again ? it could be updated? */
for_each_irq_nr(j)
- seq_put_decimal_ull(p, ' ', kstat_irqs(j));
+ seq_put_decimal_ull(p, ' ', kstat_irqs_usr(j));
seq_printf(p,
"\nctxt %llu\n"
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 51c72be4a7c3..4b2053a232c9 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -74,6 +74,7 @@ static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
* Number of interrupts per specific IRQ source, since bootup
*/
extern unsigned int kstat_irqs(unsigned int irq);
+extern unsigned int kstat_irqs_usr(unsigned int irq);
/*
* Number of interrupts per cpu, since bootup
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 001fa5bab490..8a160e8a44e8 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -74,6 +74,14 @@ extern void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu);
extern void mask_irq(struct irq_desc *desc);
extern void unmask_irq(struct irq_desc *desc);
+#ifdef CONFIG_SPARSE_IRQ
+extern void irq_lock_sparse(void);
+extern void irq_unlock_sparse(void);
+#else
+static inline void irq_lock_sparse(void) { }
+static inline void irq_unlock_sparse(void) { }
+#endif
+
extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr);
irqreturn_t handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action);
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 8ab8e9390297..07d45516b540 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -131,6 +131,16 @@ static void free_masks(struct irq_desc *desc)
static inline void free_masks(struct irq_desc *desc) { }
#endif
+void irq_lock_sparse(void)
+{
+ mutex_lock(&sparse_irq_lock);
+}
+
+void irq_unlock_sparse(void)
+{
+ mutex_unlock(&sparse_irq_lock);
+}
+
static struct irq_desc *alloc_desc(int irq, int node, struct module *owner)
{
struct irq_desc *desc;
@@ -167,6 +177,12 @@ static void free_desc(unsigned int irq)
unregister_irq_proc(irq, desc);
+ /*
+ * sparse_irq_lock protects also show_interrupts() and
+ * kstat_irq_usr(). Once we deleted the descriptor from the
+ * sparse tree we can free it. Access in proc will fail to
+ * lookup the descriptor.
+ */
mutex_lock(&sparse_irq_lock);
delete_irq_desc(irq);
mutex_unlock(&sparse_irq_lock);
@@ -489,6 +505,15 @@ void dynamic_irq_cleanup(unsigned int irq)
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
+/**
+ * kstat_irqs_cpu - Get the statistics for an interrupt on a cpu
+ * @irq: The interrupt number
+ * @cpu: The cpu number
+ *
+ * Returns the sum of interrupt counts on @cpu since boot for
+ * @irq. The caller must ensure that the interrupt is not removed
+ * concurrently.
+ */
unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
struct irq_desc *desc = irq_to_desc(irq);
@@ -497,6 +522,14 @@ unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
*per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
}
+/**
+ * kstat_irqs - Get the statistics for an interrupt
+ * @irq: The interrupt number
+ *
+ * Returns the sum of interrupt counts on all cpus since boot for
+ * @irq. The caller must ensure that the interrupt is not removed
+ * concurrently.
+ */
unsigned int kstat_irqs(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
@@ -509,3 +542,22 @@ unsigned int kstat_irqs(unsigned int irq)
sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
return sum;
}
+
+/**
+ * kstat_irqs_usr - Get the statistics for an interrupt
+ * @irq: The interrupt number
+ *
+ * Returns the sum of interrupt counts on all cpus since boot for
+ * @irq. Contrary to kstat_irqs() this can be called from any
+ * preemptible context. It's protected against concurrent removal of
+ * an interrupt descriptor when sparse irqs are enabled.
+ */
+unsigned int kstat_irqs_usr(unsigned int irq)
+{
+ int sum;
+
+ irq_lock_sparse();
+ sum = kstat_irqs(irq);
+ irq_unlock_sparse();
+ return sum;
+}
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 36f6ee181b0c..095cd7230aef 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -15,6 +15,23 @@
#include "internals.h"
+/*
+ * Access rules:
+ *
+ * procfs protects read/write of /proc/irq/N/ files against a
+ * concurrent free of the interrupt descriptor. remove_proc_entry()
+ * immediately prevents new read/writes to happen and waits for
+ * already running read/write functions to complete.
+ *
+ * We remove the proc entries first and then delete the interrupt
+ * descriptor from the radix tree and free it. So it is guaranteed
+ * that irq_to_desc(N) is valid as long as the read/writes are
+ * permitted by procfs.
+ *
+ * The read from /proc/interrupts is a different problem because there
+ * is no protection. So the lookup and the access to irqdesc
+ * information must be protected by sparse_irq_lock.
+ */
static struct proc_dir_entry *root_irq_dir;
#ifdef CONFIG_SMP
@@ -437,9 +454,10 @@ int show_interrupts(struct seq_file *p, void *v)
seq_putc(p, '\n');
}
+ irq_lock_sparse();
desc = irq_to_desc(i);
if (!desc)
- return 0;
+ goto outsparse;
raw_spin_lock_irqsave(&desc->lock, flags);
for_each_online_cpu(j)
@@ -479,6 +497,8 @@ int show_interrupts(struct seq_file *p, void *v)
seq_putc(p, '\n');
out:
raw_spin_unlock_irqrestore(&desc->lock, flags);
+outsparse:
+ irq_unlock_sparse();
return 0;
}
#endif