diff options
| author | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-04-12 12:34:41 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-08-13 14:34:50 -0700 |
| commit | 1bb5f9b95afe5d9d6b586389ce5e8f461a5b671c (patch) | |
| tree | e9fbae8771f5b45cc11b299883c3d477902642f1 | |
| parent | 18cd8c93e69e3853eb408980089fb3c58813f922 (diff) | |
rcu/nocb: Use separate flag to indicate disabled ->cblist
NULLing the RCU_NEXT_TAIL pointer was a clever way to save a byte, but
forward-progress considerations would require that this pointer be both
NULL and non-NULL, which, absent a quantum-computer port of the Linux
kernel, simply won't happen. This commit therefore creates as separate
->enabled flag to replace the current NULL checks.
[ paulmck: Add include files per 0day test robot and -next. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| -rw-r--r-- | include/linux/rcu_segcblist.h | 4 | ||||
| -rw-r--r-- | kernel/rcu/rcu_segcblist.c | 3 | ||||
| -rw-r--r-- | kernel/rcu/rcu_segcblist.h | 2 | ||||
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 2 |
4 files changed, 8 insertions, 3 deletions
diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h index 87404cb015f1..ed2cfd3c0743 100644 --- a/include/linux/rcu_segcblist.h +++ b/include/linux/rcu_segcblist.h @@ -14,6 +14,9 @@ #ifndef __INCLUDE_LINUX_RCU_SEGCBLIST_H #define __INCLUDE_LINUX_RCU_SEGCBLIST_H +#include <linux/types.h> +#include <linux/atomic.h> + /* Simple unsegmented callback lists. */ struct rcu_cblist { struct rcu_head *head; @@ -67,6 +70,7 @@ struct rcu_segcblist { unsigned long gp_seq[RCU_CBLIST_NSEGS]; long len; long len_lazy; + u8 enabled; }; #define RCU_SEGCBLIST_INITIALIZER(n) \ diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index 9bd5f6023c21..b305dcac34c9 100644 --- a/kernel/rcu/rcu_segcblist.c +++ b/kernel/rcu/rcu_segcblist.c @@ -58,6 +58,7 @@ void rcu_segcblist_init(struct rcu_segcblist *rsclp) rsclp->tails[i] = &rsclp->head; rsclp->len = 0; rsclp->len_lazy = 0; + rsclp->enabled = 1; } /* @@ -69,7 +70,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp) WARN_ON_ONCE(!rcu_segcblist_empty(rsclp)); WARN_ON_ONCE(rcu_segcblist_n_cbs(rsclp)); WARN_ON_ONCE(rcu_segcblist_n_lazy_cbs(rsclp)); - rsclp->tails[RCU_NEXT_TAIL] = NULL; + rsclp->enabled = 0; } /* diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h index 822a39da0533..b2de7b32da29 100644 --- a/kernel/rcu/rcu_segcblist.h +++ b/kernel/rcu/rcu_segcblist.h @@ -63,7 +63,7 @@ static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp) */ static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp) { - return !!rsclp->tails[RCU_NEXT_TAIL]; + return rsclp->enabled; } /* diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 0a3f8680b450..b8a43cf9bb4e 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2189,8 +2189,8 @@ static bool init_nocb_callback_list(struct rcu_data *rdp) rcu_segcblist_n_cbs(&rdp->cblist)); atomic_long_set(&rdp->nocb_q_count_lazy, rcu_segcblist_n_lazy_cbs(&rdp->cblist)); - rcu_segcblist_init(&rdp->cblist); } + rcu_segcblist_init(&rdp->cblist); rcu_segcblist_disable(&rdp->cblist); return true; } |