Messages in this thread Patch in this message | | | From | Nicholas Mc Guire <> | Subject | [PATCH RFC v2] sched: completion: locks should not be needed for reading completion state | Date | Fri, 23 Jan 2015 12:46:40 +0100 |
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Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at> ---
v2: proper subsystem tag in subject line
The ACCESS_ONCE is needed for calls in a loop that, if inlined, could optimize out the re-fetching of x->done. An explicit memory barrier is not needed as complete() and complete_all() imply a barrier.
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
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