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From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: mingo@kernel.org, tglx@linutronix.de, juri.lelli@arm.com,
	xlpang@redhat.com, linux-kernel@vger.kernel.org,
	mathieu.desnoyers@efficios.com, jdesfossez@efficios.com,
	bristot@redhat.com, Ingo Molnar <mingo@redhat.com>
Subject: Re: [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for deadline tasks
Date: Tue, 14 Jun 2016 22:28:34 +0200	[thread overview]
Message-ID: <20160614202834.GF30909@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160614144217.2b5e71ad@grimm.local.home>

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.

  reply	other threads:[~2016-06-14 20:28 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-07 19:56 [RFC][PATCH 0/8] PI and assorted failings Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 1/8] rtmutex: Deboost before waking up the top waiter Peter Zijlstra
2016-06-14  9:09   ` Juri Lelli
2016-06-14 12:54     ` Peter Zijlstra
2016-06-14 13:20       ` Juri Lelli
2016-06-14 13:59         ` Peter Zijlstra
2016-06-14 16:36     ` Davidlohr Bueso
2016-06-14 17:01       ` Juri Lelli
2016-06-14 18:22   ` Steven Rostedt
2016-06-07 19:56 ` [RFC][PATCH 2/8] sched/rtmutex/deadline: Fix a PI crash for deadline tasks Peter Zijlstra
2016-06-14 10:21   ` Juri Lelli
2016-06-14 12:30     ` Peter Zijlstra
2016-06-14 12:53     ` Xunlei Pang
2016-06-14 13:07       ` Juri Lelli
2016-06-14 16:39         ` Juri Lelli
2016-06-14 18:42   ` Steven Rostedt
2016-06-14 20:28     ` Peter Zijlstra [this message]
2016-06-15 16:14       ` Steven Rostedt
2016-06-07 19:56 ` [RFC][PATCH 3/8] sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update Peter Zijlstra
2016-06-14 10:43   ` Juri Lelli
2016-06-14 12:09     ` Peter Zijlstra
2016-06-15 16:30   ` Steven Rostedt
2016-06-15 17:55     ` Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 4/8] rtmutex: Remove rt_mutex_fastunlock() Peter Zijlstra
2016-06-15 16:43   ` Steven Rostedt
2016-06-07 19:56 ` [RFC][PATCH 5/8] rtmutex: Clean up Peter Zijlstra
2016-06-14 12:08   ` Juri Lelli
2016-06-14 12:32     ` Peter Zijlstra
2016-06-14 12:41       ` Juri Lelli
2016-06-07 19:56 ` [RFC][PATCH 6/8] sched/rtmutex: Refactor rt_mutex_setprio() Peter Zijlstra
2016-06-14 13:14   ` Juri Lelli
2016-06-14 14:08     ` Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 7/8] sched,tracing: Update trace_sched_pi_setprio() Peter Zijlstra
2016-06-07 19:56 ` [RFC][PATCH 8/8] rtmutex: Fix PI chain order integrity Peter Zijlstra
2016-06-14 17:39   ` Juri Lelli
2016-06-14 19:44     ` Peter Zijlstra
2016-06-15  7:25       ` Juri Lelli
2016-06-27 12:23         ` Peter Zijlstra
2016-06-27 12:40           ` Thomas Gleixner
2016-06-28  9:05           ` Juri Lelli

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