On Mon, May 18, 2009 at 02:59:52PM +0800, Lai Jiangshan wrote:
> Paul E. McKenney wrote:
> > +void sched_expedited_wake(void *unused)
> > +{
> > + mutex_lock(&__get_cpu_var(sched_expedited_done_mutex));
> > + if (__get_cpu_var(sched_expedited_done_qs) ==
> > + SCHED_EXPEDITED_QS_DONE_QS) {
> > + __get_cpu_var(sched_expedited_done_qs) =
> > + SCHED_EXPEDITED_QS_NEED_QS;
> > + wake_up(&__get_cpu_var(sched_expedited_qs_wq));
> > + }
> > + mutex_unlock(&__get_cpu_var(sched_expedited_done_mutex));
> > +}
>
> [...]
>
> > + get_online_cpus();
> > + preempt_disable();
> > + mycpu = smp_processor_id();
> > + smp_call_function(sched_expedited_wake, NULL, 1);
>
> sched_expedited_wake() calls mutex_lock() which may sleep?
Good eyes! Fixing this and the failure to release this lock in
krcu_sched_expedited_percpu() allows it to survive 10 hours of
rcutorture running in parallel with onlining/offlining random CPUs.
> And I think you have re-implement workqueue.
Hmmm... I suppose I could use schedule_work(), though I am concerned
about interference from other work. But I will give this some thought.
Thanx, Paul
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