From: Jonathan Nieder <jrnieder@gmail.com>
Date: Sun, 1 May 2011 09:29:37 +0000 (-0300)
Subject: cx88: fix locking of sub-driver operations
X-Git-Tag: v2.6.39.1~41
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=09c90392d070959e7f4b7942482326aa502298f0;p=pandora-kernel.git

cx88: fix locking of sub-driver operations

commit 1fe70e963028f34ba5e32488a7870ff4b410b19b upstream.

The BKL conversion of this driver seems to have gone wrong.
Loading the cx88-blackbird driver deadlocks.

The cause: mpeg_ops::open in the cx2388x blackbird driver acquires the
device lock and calls the sub-driver's request_acquire, which tries to
acquire the lock again.  Fix it by clarifying the semantics of
request_acquire, request_release, advise_acquire, and advise_release:
now all will rely on the caller to acquire the device lock.

Based on work by Ben Hutchings <ben@decadent.org.uk>.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=31962

Reported-by: Andi Huber <hobrom@gmx.at>
Tested-by: Andi Huber <hobrom@gmx.at>
Tested-by: Marlon de Boer <marlon@hyves.nl>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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