dma-buf/sync_file: only enable fence signalling on poll()
Signalling doesn't need to be enabled at sync_file creation, it is only
required if userspace waiting the fence to signal through poll().
Thus we delay fence_add_callback() until poll is called. It only adds the
callback the first time poll() is called. This avoid re-adding the same
callback multiple times.
v2: rebase and update to work with new fence support for sync_file
v3: use atomic operation to set enabled and protect fence_add_callback()
v4: use user bit from fence flags (comment from Chris Wilson)
v5: use ternary if on poll return (comment from Chris Wilson)
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: remove unused var status]
Link: http://patchwork.freedesktop.org/patch/msgid/1470404378-27961-1-git-send-email-gustavo@padovan.org
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
index f7de5a0..aa17ccf 100644
--- a/include/linux/sync_file.h
+++ b/include/linux/sync_file.h
@@ -45,6 +45,8 @@
struct fence_cb cb;
};
+#define POLL_ENABLED FENCE_FLAG_USER_BITS
+
struct sync_file *sync_file_create(struct fence *fence);
struct fence *sync_file_get_fence(int fd);