Date: Mon, 27 Jul 2026 16:12:35 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 3c6f63902b03 - main - pthread_cond_wait.3: describe spurious wakeups Message-ID: <6a678373.1dc99.30c0735b@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=3c6f63902b037e36648fae435d4d5f56f9dc389b commit 3c6f63902b037e36648fae435d4d5f56f9dc389b Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2026-07-25 20:02:24 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-07-27 16:12:12 +0000 pthread_cond_wait.3: describe spurious wakeups Reviewed by: markc Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D58458 --- share/man/man3/pthread_cond_wait.3 | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/share/man/man3/pthread_cond_wait.3 b/share/man/man3/pthread_cond_wait.3 index c09e7aa68738..d26602c69cfc 100644 --- a/share/man/man3/pthread_cond_wait.3 +++ b/share/man/man3/pthread_cond_wait.3 @@ -45,13 +45,26 @@ variable specified by .Fa cond , and releases the mutex specified by .Fa mutex . -The waiting thread unblocks only after another thread calls +The waiting thread unblocks after another thread calls .Xr pthread_cond_signal 3 , or .Xr pthread_cond_broadcast 3 with the same condition variable, and the current thread reacquires the lock on .Fa mutex . +.Pp +It is possible that the +.Fn pthread_cond_wait +function returns without corresponding wakeup from either +.Fn pthread_cond_signal +or +.Fn pthread_cond_broadcast . +Such condition is called spurious wakeup, and is allowed by +.St -p1003.1-96 . +Applications should have a boolean expression used for each wait +on the condition variable, and recheck it after return from the +.Fn pthread_cond_wait +function. .Sh RETURN VALUES If successful, the .Fn pthread_cond_waithome | help
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