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authorChris Wilson <chris@chris-wilson.co.uk>2016-08-29 19:16:13 +0100
committerSumit Semwal <sumit.semwal@linaro.org>2016-09-13 20:09:49 +0530
commitecebca79f6976ddaddfd054d699272515869ea28 (patch)
tree2afcc2ba082109305f86932c6c3751870fe6804a /drivers/dma-buf
parentf6ce410a59a48aff47bb7e18ab40497e4e80d275 (diff)
downloadop-kernel-dev-ecebca79f6976ddaddfd054d699272515869ea28.zip
op-kernel-dev-ecebca79f6976ddaddfd054d699272515869ea28.tar.gz
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')
-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 486d29c..abb5fda 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);
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