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srcu: Simplify __srcu_read_unlock() via this_cpu_dec() 

This commit replaces disabling of preemption and decrement of a per-CPU
variable with this_cpu_dec(), which avoids preemption disabling on x86
and shortens the code on all platforms.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Lai Jiangshan 2012-11-29 16:46:02 +08:00 committed by Paul E. McKenney
parent 0351096eb0
commit 5a41344a3d
1 changed files with 1 additions and 3 deletions
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4
kernel/srcu.c
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@ -321,10 +321,8 @@ 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);