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locking/percpu-rwsem: Clean up the lockdep annotations in percpu_down_read() 

Based on Peter Zijlstra's earlier patch.

Change percpu_down_read() to use __down_read(), this way we can
do rwsem_acquire_read() unconditionally at the start to make this
code more symmetric and clean.

Originally-From: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Oleg Nesterov 2015-08-21 19:43:03 +02:00 committed by Paul E. McKenney
parent f324a76324
commit cc5f730b41
1 changed files with 6 additions and 6 deletions
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12
kernel/locking/percpu-rwsem.c
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@ -70,14 +70,14 @@ static bool update_fast_ctr(struct percpu_rw_semaphore *brw, unsigned int val)
void percpu_down_read(struct percpu_rw_semaphore *brw)
{
might_sleep();
if (likely(update_fast_ctr(brw, +1))) {
rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_);
return;
}
rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_);
down_read(&brw->rw_sem);
if (likely(update_fast_ctr(brw, +1)))
return;
/* Avoid rwsem_acquire_read() and rwsem_release() */
__down_read(&brw->rw_sem);
atomic_inc(&brw->slow_read_ctr);
/* avoid up_read()->rwsem_release() */
__up_read(&brw->rw_sem);
}
EXPORT_SYMBOL_GPL(percpu_down_read);