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Re: [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for deadline tasks

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
Date 2016-06-14 22:30 +0200
Message-ID <rK38e-1hi-33@gated-at.bofh.it> (permalink)
References <rHvDI-7fg-35@gated-at.bofh.it> <rHvNo-7ix-27@gated-at.bofh.it> <rK1zr-bN-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tue, Jun 14, 2016 at 02:42:17PM -0400, Steven Rostedt wrote:
> On Tue, 07 Jun 2016 21:56:37 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
> > +	/*
> > +	 * We should deboost before waking the top waiter task such that
> > +	 * we don't run two tasks with the 'same' priority. This however
> > +	 * can lead to prio-inversion if we would get preempted after
> > +	 * the deboost but before waking our high-prio task, hence the
> > +	 * preempt_disable before unlock. Pairs with preempt_enable() in
> > +	 * rt_mutex_postunlock();
> > +	 */
> > +	preempt_disable();
> > +
> 
> This looks like a possible maintenance nightmare. Can we add some more
> comments at the start of the functions that state that
> rt_mutex_slowunlock() calls must be paired with rt_mutex_postunlock()?

Please look at patches 4 and 5 that clean this up.

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Re: [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for  deadline tasks Steven Rostedt <rostedt@goodmis.org> - 2016-06-14 20:50 +0200
  Re: [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for  deadline tasks Peter Zijlstra <peterz@infradead.org> - 2016-06-14 22:30 +0200
    Re: [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for  deadline tasks Steven Rostedt <rostedt@goodmis.org> - 2016-06-15 18:20 +0200

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