From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH RT 1/3] rt: Move migrate_disable up in trylocks
Date: Fri, 2 May 2014 17:31:53 +0200
Message-ID: <20140502153153.GG9178@linutronix.de>
References: <20140501004757.583708392@goodmis.org>
 <20140501005004.241785945@goodmis.org>
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	linux-rt-users <linux-rt-users@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Carsten Emde <C.Emde@osadl.org>,
	John Kacur <jkacur@redhat.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Mike Galbraith <umgwanakikbuti@gmail.com>,
	Nicholas Mc Guire <der.herr@hofr.at>,
	Clark Williams <williams@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
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* Steven Rostedt | 2014-04-30 20:47:58 [-0400]:

>From: Steven Rostedt <rostedt@goodmis.org>
>
>The changes to move the migrate_disable() down in the trylocks()
>caused race conditions to appear in the cpu hotplug code. The
>migrate disables must be done before any of the rtmutexes are
>taken, otherwise a lock may be held that prevents hotplug from
>moving forward.
>
>Link: http://lkml.kernel.org/r/20140429201308.63292691@gandalf.local.home

Okay. I am taking a modified version (so it applies) of this into v3.14
tree. Mike also suggested to drop
migrate_disable-pushd-down-in-atomic_dec_and_spin_lo.patch because we
which is basicaly the some thing. And then we have
migrate_disable-pushd-down-in-rt_spin_trylock_irqsav.patch which we
could drop as well for the same reason.

Sebastian