[media] uvcvideo: Don't call vb2 mmap and get_unmapped_area with queue lock held
authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Mon, 16 Feb 2015 17:38:28 +0000 (14:38 -0300)
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>
Thu, 2 Apr 2015 20:29:28 +0000 (17:29 -0300)
commit9e68c53910721ffc55c05ee9bbc08129c796b470
treeb46ceedf3b73da8a2c9405ab6afb22e4bef4ed1a
parentcfa967224382f8ac3adbb40117be776838b91ebc
[media] uvcvideo: Don't call vb2 mmap and get_unmapped_area with queue lock held

videobuf2 has long been subject to AB-BA style deadlocks due to the
queue lock and mmap_sem being taken in different orders for the mmap and
get_unmapped_area operations. The problem has been fixed by making those
two operations callable without taking the queue lock, using an
mmap_lock internal to videobuf2.

The uvcvideo driver still calls the mmap and get_unmapped_area
operations with the queue lock held, resulting in a potential deadlock.
As the operations can now be called without locking the queue, fix it.

Reported-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
drivers/media/usb/uvc/uvc_queue.c