From 6f942a1f264e875c5f3ad6f505d7b500a3e7fa82 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 24 Sep 2014 10:18:46 +0200 Subject: [PATCH] locking/mutex: Don't assume TASK_RUNNING We're going to make might_sleep() test for TASK_RUNNING, because blocking without TASK_RUNNING will destroy the task state by setting it to TASK_RUNNING. There are a few occasions where its 'valid' to call blocking primitives (and mutex_lock in particular) and not have TASK_RUNNING, typically such cases are right before we set TASK_RUNNING anyhow. Robustify the code by not assuming this; this has the beneficial side effect of allowing optional code emission for fixing the above might_sleep() false positives. Signed-off-by: Peter Zijlstra (Intel) Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: Oleg Nesterov Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20140924082241.988560063@infradead.org Signed-off-by: Ingo Molnar --- kernel/locking/mutex.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index dadbf88c22c4..454195194d4a 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -378,8 +378,14 @@ done: * reschedule now, before we try-lock the mutex. This avoids getting * scheduled out right after we obtained the mutex. */ - if (need_resched()) + if (need_resched()) { + /* + * We _should_ have TASK_RUNNING here, but just in case + * we do not, make it so, otherwise we might get stuck. + */ + __set_current_state(TASK_RUNNING); schedule_preempt_disabled(); + } return false; }