From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: linux-kernel@vger.kernel.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Subject: [PATCH 1/8] srcu: simplify __srcu_read_unlock() via this_cpu_dec()
Date: Thu, 29 Nov 2012 16:46:02 +0800 [thread overview]
Message-ID: <1354178770-6028-2-git-send-email-laijs@cn.fujitsu.com> (raw)
In-Reply-To: <1354178770-6028-1-git-send-email-laijs@cn.fujitsu.com>
this_cpu_dec() can do the same thing and sometimes it is better.
(avoid preempt_disable() and use more tiny instructions)
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/srcu.c | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/kernel/srcu.c b/kernel/srcu.c
index b363b09..b2e4f36 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -317,10 +317,8 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock);
*/
void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{
- preempt_disable();
smp_mb(); /* C */ /* Avoid leaking the critical section. */
- ACCESS_ONCE(this_cpu_ptr(sp->per_cpu_ref)->c[idx]) -= 1;
- preempt_enable();
+ this_cpu_dec(sp->per_cpu_ref->c[idx]);
}
EXPORT_SYMBOL_GPL(__srcu_read_unlock);
--
1.7.4.4
next prev parent reply other threads:[~2012-11-29 8:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-29 8:46 [PATCH 0/8] srcu: cleanup for 3.8 Lai Jiangshan
2012-11-29 8:46 ` Lai Jiangshan [this message]
2012-11-29 8:46 ` [PATCH 2/8] srcu: add might_sleep() annotation to synchronize_srcu() Lai Jiangshan
2012-11-29 8:46 ` [PATCH 3/8] srcu: simple cleanup for cleanup_srcu_struct() Lai Jiangshan
2012-11-29 8:46 ` [PATCH 4/8] srcu: srcu_read_lock() can be called from offline cpu Lai Jiangshan
2012-12-04 19:15 ` Paul E. McKenney
2012-11-29 8:46 ` [PATCH 5/8] srcu: srcu_read_lock() can be called from idle loop Lai Jiangshan
2012-11-29 8:46 ` [PATCH 6/8] srcu: update the comments of synchronize_srcu() Lai Jiangshan
2012-11-29 8:46 ` [PATCH 7/8] srcu: update the comments of synchronize_srcu_expedited() Lai Jiangshan
2012-11-29 8:46 ` [PATCH 8/8] srcu: use ACCESS_ONCE() to access sp->completed in srcu_read_lock() Lai Jiangshan
2012-11-29 22:05 ` Paul E. McKenney
2012-11-30 8:14 ` Lai Jiangshan
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