* [PATCH] locks should not be needed for reading completion state
@ 2015-01-17 4:05 Nicholas Mc Guire
2015-02-04 14:37 ` [tip:locking/core] sched/completion: Remove unnecessary -> wait.lock serialization when " tip-bot for Nicholas Mc Guire
0 siblings, 1 reply; 2+ messages in thread
From: Nicholas Mc Guire @ 2015-01-17 4:05 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Peter Zijlstra, linux-kernel, Nicholas Mc Guire
Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
---
Should that not be enough to wrap it into ACCESS_ONCE() here ?
Not a wild performance benefit - but might be worth it anyway
kernel/sched/completion.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
index 607f852..7c5cd70 100644
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -288,13 +288,6 @@ EXPORT_SYMBOL(try_wait_for_completion);
*/
bool completion_done(struct completion *x)
{
- unsigned long flags;
- int ret = 1;
-
- spin_lock_irqsave(&x->wait.lock, flags);
- if (!x->done)
- ret = 0;
- spin_unlock_irqrestore(&x->wait.lock, flags);
- return ret;
+ return !ACCESS_ONCE(x->done);
}
EXPORT_SYMBOL(completion_done);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:locking/core] sched/completion: Remove unnecessary -> wait.lock serialization when reading completion state
2015-01-17 4:05 [PATCH] locks should not be needed for reading completion state Nicholas Mc Guire
@ 2015-02-04 14:37 ` tip-bot for Nicholas Mc Guire
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Nicholas Mc Guire @ 2015-02-04 14:37 UTC (permalink / raw)
To: linux-tip-commits
Cc: hpa, der.herr, peterz, linux-kernel, tglx, torvalds, mingo
Commit-ID: de30ec47302c101c7badc8fe687641fd75e596e7
Gitweb: http://git.kernel.org/tip/de30ec47302c101c7badc8fe687641fd75e596e7
Author: Nicholas Mc Guire <der.herr@hofr.at>
AuthorDate: Sat, 17 Jan 2015 05:05:34 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 4 Feb 2015 07:57:36 +0100
sched/completion: Remove unnecessary ->wait.lock serialization when reading completion state
Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1421467534-22834-1-git-send-email-der.herr@hofr.at
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/completion.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
index 607f852..9d1fe32d 100644
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -288,13 +288,6 @@ EXPORT_SYMBOL(try_wait_for_completion);
*/
bool completion_done(struct completion *x)
{
- unsigned long flags;
- int ret = 1;
-
- spin_lock_irqsave(&x->wait.lock, flags);
- if (!x->done)
- ret = 0;
- spin_unlock_irqrestore(&x->wait.lock, flags);
- return ret;
+ return !!ACCESS_ONCE(x->done);
}
EXPORT_SYMBOL(completion_done);
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2015-02-04 14:38 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-01-17 4:05 [PATCH] locks should not be needed for reading completion state Nicholas Mc Guire
2015-02-04 14:37 ` [tip:locking/core] sched/completion: Remove unnecessary -> wait.lock serialization when " tip-bot for Nicholas Mc Guire
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).