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authorHans Verkuil <hans.verkuil@cisco.com>2015-01-19 06:16:18 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-01-21 21:07:26 -0200
commit6cf11ee6300f38b7cfc43af9b7be2afaa5e05869 (patch)
treed6df278332bd72f37c6d6f38586d1fc2a7b57cb5
parent42d74e4fe6508308abc1baac95ba36ad0cc5143e (diff)
downloadlinux-6cf11ee6300f38b7cfc43af9b7be2afaa5e05869.tar.gz
[media] vb2: fix vb2_thread_stop race conditions
The locking scheme inside the vb2 thread is unsafe when stopping the thread. In particular kthread_stop was called *after* internal data structures were cleaned up instead of doing that before. In addition, internal vb2 functions were called after threadio->stop was set to true and vb2_internal_streamoff was called. This is also not allowed. All this led to a variety of race conditions and kernel warnings and/or oopses. Fixed by moving the kthread_stop call up before the cleanup takes place, and by checking threadio->stop before calling internal vb2 queuing operations. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Cc: <stable@vger.kernel.org> # for v3.16 and up Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
-rw-r--r--drivers/media/v4l2-core/videobuf2-core.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index d09a8916e94..bc08a829bc1 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -3146,27 +3146,26 @@ static int vb2_thread(void *data)
prequeue--;
} else {
call_void_qop(q, wait_finish, q);
- ret = vb2_internal_dqbuf(q, &fileio->b, 0);
+ if (!threadio->stop)
+ ret = vb2_internal_dqbuf(q, &fileio->b, 0);
call_void_qop(q, wait_prepare, q);
dprintk(5, "file io: vb2_dqbuf result: %d\n", ret);
}
- if (threadio->stop)
- break;
- if (ret)
+ if (ret || threadio->stop)
break;
try_to_freeze();
vb = q->bufs[fileio->b.index];
if (!(fileio->b.flags & V4L2_BUF_FLAG_ERROR))
- ret = threadio->fnc(vb, threadio->priv);
- if (ret)
- break;
+ if (threadio->fnc(vb, threadio->priv))
+ break;
call_void_qop(q, wait_finish, q);
if (set_timestamp)
v4l2_get_timestamp(&fileio->b.timestamp);
- ret = vb2_internal_qbuf(q, &fileio->b);
+ if (!threadio->stop)
+ ret = vb2_internal_qbuf(q, &fileio->b);
call_void_qop(q, wait_prepare, q);
- if (ret)
+ if (ret || threadio->stop)
break;
}
@@ -3235,11 +3234,11 @@ int vb2_thread_stop(struct vb2_queue *q)
threadio->stop = true;
vb2_internal_streamoff(q, q->type);
call_void_qop(q, wait_prepare, q);
+ err = kthread_stop(threadio->thread);
q->fileio = NULL;
fileio->req.count = 0;
vb2_reqbufs(q, &fileio->req);
kfree(fileio);
- err = kthread_stop(threadio->thread);
threadio->thread = NULL;
kfree(threadio);
q->fileio = NULL;