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authorChris Wilson <chris@chris-wilson.co.uk>2016-08-29 20:16:13 +0200
committerSumit Semwal <sumit.semwal@linaro.org>2016-09-13 16:39:49 +0200
commitecebca79f6976ddaddfd054d699272515869ea28 (patch)
tree2afcc2ba082109305f86932c6c3751870fe6804a /drivers/dma-buf/sync_file.c
parentdrm/fence: allow fence waiting to be interrupted by userspace (diff)
downloadlinux-ecebca79f6976ddaddfd054d699272515869ea28.tar.xz
linux-ecebca79f6976ddaddfd054d699272515869ea28.zip
dma-buf/sync-file: Avoid enable fence signaling if poll(.timeout=0)
If we being polled with a timeout of zero, a nonblocking busy query, we don't need to install any fence callbacks as we will not be waiting. As we only install the callback once, the overhead comes from the atomic bit test that also causes serialisation between threads. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Gustavo Padovan <gustavo@padovan.org> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: http://patchwork.freedesktop.org/patch/msgid/20160829181613.30722-1-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/dma-buf/sync_file.c')
-rw-r--r--drivers/dma-buf/sync_file.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 486d29c1a830..abb5fdab75fd 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -306,7 +306,8 @@ static unsigned int sync_file_poll(struct file *file, poll_table *wait)
poll_wait(file, &sync_file->wq, wait);
- if (!test_and_set_bit(POLL_ENABLED, &sync_file->fence->flags)) {
+ if (!poll_does_not_wait(wait) &&
+ !test_and_set_bit(POLL_ENABLED, &sync_file->fence->flags)) {
if (fence_add_callback(sync_file->fence, &sync_file->cb,
fence_check_cb_func) < 0)
wake_up_all(&sync_file->wq);