From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 10 Mar 2009 21:44:01 +0000 (+0100)
Subject: HID: fix waitqueue usage in hiddev
X-Git-Tag: v2.6.29~17^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=96fe2ab830d7dffee1b3d8abf27ced4d7d5765e7;p=pandora-kernel.git

HID: fix waitqueue usage in hiddev

DECLARE_WAITQUEUE doesn't initialize the wait descriptor's task_list
to 'empty' but to zero.

prepare_to_wait() will not enqueue the descriptor to the waitqueue and
finish_wait() will do list_del_init() on a list head that contains
NULL pointers, which oopses.

This was introduced by 079034073 "HID: hiddev cleanup -- handle all
error conditions properly".

The prior code used an unconditional add_to_waitqueue() which didn't
care about the wait descriptor's list head and enqueued the thing
unconditionally.

The new code uses prepare_to_wait() which DOES check the prior list
state, so use DEFINE_WAIT instead.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oliver Neukum <oliver@neukum.name>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---

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