From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Sat, 1 Nov 2014 13:32:28 +0000 (-0300)
Subject: [media] v4l: vb2: Fix race condition in vb2_fop_poll
X-Git-Tag: omap-for-v3.19/fixes-rc1~133^2~30
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f6cee18858b3c0adaa30cbe45a1766c8ef053c5d;p=pandora-kernel.git

[media] v4l: vb2: Fix race condition in vb2_fop_poll

The vb2_fop_poll() implementation tries to be clever on whether it needs
to lock the queue mutex by checking whether polling might start fileio.
The test requires reading the q->num_buffer field, which is racy if we
don't hold the queue mutex in the first place.

Remove the extra cleverness and just lock the mutex.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
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