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From: Thomas Gleixner <tglx@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Brad Mouring <bmouring@ni.com>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Clark Williams <williams@redhat.com>
Subject: Re: [PATCH 1/1] rtmutex: Handle when top lock owner changes
Date: Fri, 6 Jun 2014 07:44:23 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.10.1406060743260.23174@nanos> (raw)
In-Reply-To: <alpine.DEB.2.10.1406060739030.23174@nanos>

On Fri, 6 Jun 2014, Thomas Gleixner wrote:
> On Thu, 5 Jun 2014, Steven Rostedt wrote:
> > On Wed, 4 Jun 2014 17:32:37 +0200 (CEST)
> > Thomas Gleixner <tglx@linutronix.de> wrote:
> > +	/*
> > +	 * When we dropped the spinlocks, if the owner of the lock we
> > +	 * are currently processing changed since we chain walked
> > +	 * to that lock, we are done with the chain walk. The previous
> > +	 * owner was obviously running to release it.
> > +	 */
> > +	if (lock && rt_mutex_owner(lock) != task)
> > +		goto out_unlock_pi;
> 
> NO. You CANNOT derefernce lock after dropping the locks. It might be
> gone already.

The only information we can check is, whether @task changed the
blocked on lock, really.

Thanks,

	tglx



  reply	other threads:[~2014-06-06  5:44 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-23 14:30 [PATCH 0/1] Faux deadlock detection fixup Brad Mouring
2014-05-23 14:30 ` [PATCH 1/1] rtmutex: Handle when top lock owner changes Brad Mouring
2014-06-04  1:06   ` Steven Rostedt
2014-06-04 13:05     ` Brad Mouring
2014-06-04 14:16       ` Steven Rostedt
2014-06-04 14:38         ` Brad Mouring
2014-06-04 14:58           ` Steven Rostedt
2014-06-04 15:11             ` Brad Mouring
2014-06-04 15:32     ` Thomas Gleixner
2014-06-04 15:44       ` Steven Rostedt
2014-06-04 18:02         ` Thomas Gleixner
2014-06-04 18:12           ` Steven Rostedt
2014-06-04 20:49             ` Thomas Gleixner
2014-06-04 19:25           ` Brad Mouring
2014-06-04 19:53             ` Thomas Gleixner
2014-06-04 20:07               ` Brad Mouring
2014-06-04 20:41                 ` Thomas Gleixner
2014-06-04 22:22                   ` [PATCH] " Brad Mouring
2014-06-04 23:03                     ` Thomas Gleixner
2014-06-06  3:19       ` [PATCH 1/1] " Steven Rostedt
2014-06-06  5:40         ` Thomas Gleixner
2014-06-06  5:44           ` Thomas Gleixner [this message]
2014-06-06  8:53           ` Steven Rostedt

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