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[media] videobuf2-core: take mmap_sem before calling __qbuf_userptr

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(Changes since v2: dropped local variable as suggested by Laurent)

Commit f035eb4e97 (videobuf2: fix lockdep warning)
unfortunately removed the mmap_sem lock that is needed around the call to
__qbuf_userptr. Amazingly nobody noticed this (especially me as the author)
until Jan Kara pointed this out to me.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Jan Kara <jack@suse.cz>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Hans Verkuil 2014-08-25 08:57:59 -03:00 committed by Mauro Carvalho Chehab
parent 825fd08dbb
commit 12561ad622
1 changed files with 2 additions and 0 deletions
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2
drivers/media/v4l2-core/videobuf2-core.c
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@ -1627,7 +1627,9 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
ret = __qbuf_mmap(vb, b);
break;
case V4L2_MEMORY_USERPTR:
down_read(&current->mm->mmap_sem);
ret = __qbuf_userptr(vb, b);
up_read(&current->mm->mmap_sem);
break;
case V4L2_MEMORY_DMABUF:
ret = __qbuf_dmabuf(vb, b);