diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-09-13 16:15:11 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2009-09-17 22:06:53 (GMT) |
commit | 16e3081191837a6a04733de5cd5d1d1b303140d4 (patch) | |
tree | 6b64a4613b9ac57da30518626a259b6aeeef4944 | |
parent | c3422bea5f09b0e85704f51f2b01271630b8940b (diff) | |
download | linux-16e3081191837a6a04733de5cd5d1d1b303140d4.tar.xz |
rcu: Fix synchronize_rcu() for TREE_PREEMPT_RCU
The redirection of synchronize_sched() to synchronize_rcu() was
appropriate for TREE_RCU, but not for TREE_PREEMPT_RCU.
Fix this by creating an underlying synchronize_sched(). TREE_RCU
then redirects synchronize_rcu() to synchronize_sched(), while
TREE_PREEMPT_RCU has its own version of synchronize_rcu().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
LKML-Reference: <12528585111916-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r-- | include/linux/rcupdate.h | 23 | ||||
-rw-r--r-- | include/linux/rcutree.h | 4 | ||||
-rw-r--r-- | kernel/rcupdate.c | 44 |
3 files changed, 50 insertions, 21 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 95e0615..39dce83 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -52,8 +52,13 @@ struct rcu_head { }; /* Exported common interfaces */ +#ifdef CONFIG_TREE_PREEMPT_RCU extern void synchronize_rcu(void); +#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ +#define synchronize_rcu synchronize_sched +#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ extern void synchronize_rcu_bh(void); +extern void synchronize_sched(void); extern void rcu_barrier(void); extern void rcu_barrier_bh(void); extern void rcu_barrier_sched(void); @@ -262,24 +267,6 @@ struct rcu_synchronize { extern void wakeme_after_rcu(struct rcu_head *head); /** - * synchronize_sched - block until all CPUs have exited any non-preemptive - * kernel code sequences. - * - * This means that all preempt_disable code sequences, including NMI and - * hardware-interrupt handlers, in progress on entry will have completed - * before this primitive returns. However, this does not guarantee that - * softirq handlers will have completed, since in some kernels, these - * handlers can run in process context, and can block. - * - * This primitive provides the guarantees made by the (now removed) - * synchronize_kernel() API. In contrast, synchronize_rcu() only - * guarantees that rcu_read_lock() sections will have completed. - * In "classic RCU", these two guarantees happen to be one and - * the same, but can differ in realtime RCU implementations. - */ -#define synchronize_sched() __synchronize_sched() - -/** * 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 diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index a893077..00d08c0 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -53,6 +53,8 @@ static inline void __rcu_read_unlock(void) preempt_enable(); } +#define __synchronize_sched() synchronize_rcu() + static inline void exit_rcu(void) { } @@ -68,8 +70,6 @@ static inline void __rcu_read_unlock_bh(void) local_bh_enable(); } -#define __synchronize_sched() synchronize_rcu() - extern void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index bd5d5c8..28d2f24 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -74,6 +74,8 @@ void wakeme_after_rcu(struct rcu_head *head) complete(&rcu->completion); } +#ifdef CONFIG_TREE_PREEMPT_RCU + /** * synchronize_rcu - wait until a grace period has elapsed. * @@ -87,7 +89,7 @@ void synchronize_rcu(void) { struct rcu_synchronize rcu; - if (rcu_blocking_is_gp()) + if (!rcu_scheduler_active) return; init_completion(&rcu.completion); @@ -98,6 +100,46 @@ void synchronize_rcu(void) } EXPORT_SYMBOL_GPL(synchronize_rcu); +#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ + +/** + * synchronize_sched - wait until an rcu-sched grace period has elapsed. + * + * Control will return to the caller some time after a full rcu-sched + * grace period has elapsed, in other words after all currently executing + * rcu-sched read-side critical sections have completed. These read-side + * critical sections are delimited by rcu_read_lock_sched() and + * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(), + * local_irq_disable(), and so on may be used in place of + * rcu_read_lock_sched(). + * + * This means that all preempt_disable code sequences, including NMI and + * hardware-interrupt handlers, in progress on entry will have completed + * before this primitive returns. However, this does not guarantee that + * softirq handlers will have completed, since in some kernels, these + * handlers can run in process context, and can block. + * + * This primitive provides the guarantees made by the (now removed) + * synchronize_kernel() API. In contrast, synchronize_rcu() only + * guarantees that rcu_read_lock() sections will have completed. + * In "classic RCU", these two guarantees happen to be one and + * the same, but can differ in realtime RCU implementations. + */ +void synchronize_sched(void) +{ + struct rcu_synchronize rcu; + + if (rcu_blocking_is_gp()) + return; + + 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); + /** * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed. * |