From: Andrea Righi <righi.andrea@gmail.com>
Date: Wed, 4 Feb 2009 23:12:03 +0000 (-0800)
Subject: fbmem: don't call copy_from/to_user() with mutex held
X-Git-Tag: v2.6.29-rc4~44
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1f5e31d7e55ac7fbd4ec5e5b20c8868b0e4564c9;p=pandora-kernel.git

fbmem: don't call copy_from/to_user() with mutex held

Avoid calling copy_from/to_user() with fb_info->lock mutex held in fbmem
ioctl().

fb_mmap() is called under mm->mmap_sem (A) held, that also acquires
fb_info->lock (B); fb_ioctl() takes fb_info->lock (B) and does
copy_from/to_user() that might acquire mm->mmap_sem (A), causing a
deadlock.

NOTE: it doesn't push down the fb_info->lock in each own driver's
fb_ioctl(), so there are still potential deadlocks elsewhere.

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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