On Thu, Jul 31, 2014 at 03:44:11PM +0200, Ingo Molnar wrote:
>
> > diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
> > index ae712b25e492..3d726fdaa764 100644
> > --- a/kernel/locking/mutex.c
> > +++ b/kernel/locking/mutex.c
> > @@ -473,8 +473,12 @@ __mutex_lock_common(struct mutex *lock, long state,
> > unsigned int subclass,
> > * 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()) {
> > + if (WARN_ON_ONCE(current->state != TASK_RUNNING))
> > + __set_current_state(TASK_RUNNING);
> > +
> > schedule_preempt_disabled();
> > + }
>
> Might make sense to add that debug check under mutex debugging or so,
> with a sensible kernel message printed.Something like so? I suppose we should do a similar one for rwsem, semaphores and possibly wait_event*() too. --- Subject: locking/mutex: Add debug check for task state Calling blocking locks with current->state != TASK_RUNNING is a bug. Signed-off-by: Peter Zijlstra <[email protected]> --- kernel/locking/mutex.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index ae712b25e492..d5daf8c38899 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -375,6 +375,17 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, unsigned long flags; int ret; +#ifdef CONFIG_DEBUG_MUTEXES + /* + * Blocking primitives (including this one) will set (and therefore + * destroy) current->state, since we will exit with TASK_RUNNING + * make sure we enter with it, otherwise we will destroy state. + */ + if (WARN_ONCE(current->state != TASK_RUNNING, + "do not call blocking locks when !TASK_RUNNING\n")) + __set_current_state(TASK_RUNNING); +#endif + preempt_disable(); mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
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