4.4-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 699f685569434510d944e419f4048c4e3ba8d631 ]
Using fence->status to determine whether or not there are callbacks remaining on the sync_fence is racy since fence->status may have been decremented to 0 on another CPU before fence_check_cb_func() has completed. By unconditionally calling fence_remove_callback() for each fence in the sync_fence, we guarantee that each callback has either completed (since fence_remove_callback() grabs the fence lock) or been removed.
Signed-off-by: Andrew Bresticker abrestic@chromium.org Signed-off-by: Dmitry Torokhov dtor@chromium.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/staging/android/sync.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c index f83e00c78051..50a9945da27e 100644 --- a/drivers/staging/android/sync.c +++ b/drivers/staging/android/sync.c @@ -519,12 +519,10 @@ static const struct fence_ops android_fence_ops = { static void sync_fence_free(struct kref *kref) { struct sync_fence *fence = container_of(kref, struct sync_fence, kref); - int i, status = atomic_read(&fence->status); + int i;
for (i = 0; i < fence->num_fences; ++i) { - if (status) - fence_remove_callback(fence->cbs[i].sync_pt, - &fence->cbs[i].cb); + fence_remove_callback(fence->cbs[i].sync_pt, &fence->cbs[i].cb); fence_put(fence->cbs[i].sync_pt); }