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Message-ID: <20150821174303.GA17920@redhat.com>
Date: Fri, 21 Aug 2015 19:43:03 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>,
Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH v2 8/8] percpu-rwsem: cleanup the lockdep annotations in
percpu_down_read()
Stolen from Peter's 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.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
kernel/locking/percpu-rwsem.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
index 69704eb..5694849 100644
--- a/kernel/locking/percpu-rwsem.c
+++ b/kernel/locking/percpu-rwsem.c
@@ -69,14 +69,14 @@ 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_);
+ rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 0, _RET_IP_);
+
+ if (likely(update_fast_ctr(brw, +1)))
return;
- }
- down_read(&brw->rw_sem);
+ /* 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);
}
--
1.5.5.1
--
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