From: Dave Jones <davej@redhat.com>
Date: Fri, 7 Jul 2006 16:31:27 +0000 (-0400)
Subject: [PATCH] Fix cpufreq vs hotplug lockdep recursion.
X-Git-Tag: v2.6.18-rc2~260
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a496e25dfb25493a57bcee5d66875d6ff80a9093;p=pandora-kernel.git

[PATCH] Fix cpufreq vs hotplug lockdep recursion.

[ There's some not quite baked bits in cpufreq-git right now
  so sending this on as a patch instead ]

On Thu, 2006-07-06 at 07:58 -0700, Tom London wrote:

> After installing .2356 I get this each time I boot:
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> -------------------------------------------------------
> S06cpuspeed/1620 is trying to acquire lock:
>  (dbs_mutex){--..}, at: [<c060d6bb>] mutex_lock+0x21/0x24
>
> but task is already holding lock:
>  (cpucontrol){--..}, at: [<c060d6bb>] mutex_lock+0x21/0x24
>
> which lock already depends on the new lock.
>

make sure the cpu hotplug recursive mutex (yuck) is taken early in the
cpufreq codepaths to avoid a AB-BA deadlock.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

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