diff options
| author | Hans Verkuil <hans.verkuil@cisco.com> | 2015-01-19 06:16:18 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-29 17:40:44 -0800 |
| commit | 7536e0dce329aabda3f06a0356ac974bcdb42cae (patch) | |
| tree | 7674dee4a43818be7ee500fe5cd27bbf192ffe1d | |
| parent | 5d9aa9e5e8eb25585367caa034bba3cdc4f59f34 (diff) | |
vb2: fix vb2_thread_stop race conditions
commit 6cf11ee6300f38b7cfc43af9b7be2afaa5e05869 upstream.
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>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/media/v4l2-core/videobuf2-core.c | 19 |
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 f2e43de3dd87..ea36447c74f9 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -3142,27 +3142,26 @@ 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; } @@ -3231,11 +3230,11 @@ 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; |