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Date: Mon, 14 Jul 2008 14:57:26 +0900 From: Tejun Heo <tj@...nel.org> To: dipankar@...ibm.com, Andrew Morton <akpm@...ux-foundation.org>, Jens Axboe <jens.axboe@...cle.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: [PATCH] RCU: implement rcu_read_[un]lock_preempt() With the introduction of preemptible RCU, RCU doesn't gurantee that its critical section runs on the CPU it started to run. As there are cases where non-preemptible RCU critical section makes sense, create new RCU read lock variants which turns of preemption - rcu_read_[un]lock_preempt() which are identical to rcu_read_[un]lock() for classic implementation and have enclosing preempt disable/enable for preemptible RCU. Signed-off-by: Tejun Heo <tj@...nel.org> --- This will be used by following block layer updates. If this and the block changes get acked, it'll be best to push this through block tree. Thanks. include/linux/rcuclassic.h | 2 ++ include/linux/rcupdate.h | 18 ++++++++++++++++++ include/linux/rcupreempt.h | 6 ++++-- 3 files changed, 24 insertions(+), 2 deletions(-) diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h index b3aa05b..08c6153 100644 --- a/include/linux/rcuclassic.h +++ b/include/linux/rcuclassic.h @@ -136,6 +136,8 @@ extern struct lockdep_map rcu_lock_map; __release(RCU); \ preempt_enable(); \ } while (0) +#define __rcu_read_lock_preempt() __rcu_read_lock() +#define __rcu_read_unlock_preempt() __rcu_read_unlock() #define __rcu_read_lock_bh() \ do { \ local_bh_disable(); \ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index d42dbec..e0e3486 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -112,6 +112,24 @@ struct rcu_head { #define rcu_read_unlock() __rcu_read_unlock() /** + * rcu_read_lock_preempt - mark the beginning of non-preemptible RCU + * critical section + * + * Identical to rcu_read_lock() but the critical section is guaranteed + * to be non-preemptible. Note that this is identical to + * rcu_read_lock() on classic RCU implementation. + */ +#define rcu_read_lock_preempt() __rcu_read_lock_preempt() + +/** + * rcu_read_unlock_preempt - mark the end of of non-preemptible RCU + * critical section + * + * See rcu_read_lock_preempt() for more information. + */ +#define rcu_read_unlock_preempt() __rcu_read_unlock_preempt() + +/** * rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical section * * This is equivalent of rcu_read_lock(), but to be used when updates diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h index 8a05c7e..b263ceb 100644 --- a/include/linux/rcupreempt.h +++ b/include/linux/rcupreempt.h @@ -49,8 +49,10 @@ extern void __rcu_read_unlock(void) __releases(RCU); extern int rcu_pending(int cpu); extern int rcu_needs_cpu(int cpu); -#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } -#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } +#define __rcu_read_lock_preempt() { rcu_read_lock(); preempt_disable(); } +#define __rcu_read_unlock_preempt() { preempt_enable(); rcu_read_unlock(); } +#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } +#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } extern void __synchronize_sched(void); -- 1.5.4.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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