diff options
author | Steven Rostedt <[email protected]> | 2017-08-16 13:12:02 -0400 |
---|---|---|
committer | Ingo Molnar <[email protected]> | 2017-08-16 20:08:10 +0200 |
commit | 9c8783201cb58e9af8ddeb0cc68f37b0a44ca16c (patch) | |
tree | 212c0a154e726ca945bc890886a1190e60568c31 | |
parent | 1e58565e6d147751d85ee9e692d1226059b3318f (diff) |
sched/completion: Document that reinit_completion() must be called after complete_all()
The complete_all() function modifies the completion's "done" variable to
UINT_MAX, and no other caller (wait_for_completion(), etc) will modify
it back to zero. That means that any call to complete_all() must have a
reinit_completion() before that completion can be used again.
Document this fact by the complete_all() function.
Also document that completion_done() will always return true if
complete_all() is called.
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
-rw-r--r-- | kernel/sched/completion.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c index 13fc5ae9bf2f..2950f446820d 100644 --- a/kernel/sched/completion.c +++ b/kernel/sched/completion.c @@ -47,6 +47,13 @@ EXPORT_SYMBOL(complete); * * It may be assumed that this function implies a write memory barrier before * changing the task state if and only if any tasks are woken up. + * + * Since complete_all() sets the completion of @x permanently to done + * to allow multiple waiters to finish, a call to reinit_completion() + * must be used on @x if @x is to be used again. The code must make + * sure that all waiters have woken and finished before reinitializing + * @x. Also note that the function completion_done() can not be used + * to know if there are still waiters after complete_all() has been called. */ void complete_all(struct completion *x) { @@ -297,6 +304,7 @@ EXPORT_SYMBOL(try_wait_for_completion); * Return: 0 if there are waiters (wait_for_completion() in progress) * 1 if there are no waiters. * + * Note, this will always return true if complete_all() was called on @X. */ bool completion_done(struct completion *x) { |