From: Gustavo Padovan gustavo.padovan@collabora.co.uk
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)
Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.co.uk --- drivers/dma-buf/sync_file.c | 22 +++++++++++++--------- include/linux/sync_file.h | 2 ++ 2 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index 2873760..ec61c50 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -86,8 +86,6 @@ struct sync_file *sync_file_create(struct fence *fence) fence->ops->get_timeline_name(fence), fence->context, fence->seqno);
- fence_add_callback(fence, &sync_file->cb, fence_check_cb_func); - return sync_file; } EXPORT_SYMBOL(sync_file_create); @@ -274,9 +272,6 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, goto err; }
- fence_add_callback(sync_file->fence, &sync_file->cb, - fence_check_cb_func); - strlcpy(sync_file->name, name, sizeof(sync_file->name)); return sync_file;
@@ -291,7 +286,8 @@ static void sync_file_free(struct kref *kref) struct sync_file *sync_file = container_of(kref, struct sync_file, kref);
- fence_remove_callback(sync_file->fence, &sync_file->cb); + if (test_bit(POLL_ENABLED, &sync_file->fence->flags)) + fence_remove_callback(sync_file->fence, &sync_file->cb); fence_put(sync_file->fence); kfree(sync_file); } @@ -311,13 +307,21 @@ 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 (fence_add_callback(sync_file->fence, &sync_file->cb, + fence_check_cb_func) < 0) + wake_up_all(&sync_file->wq); + } + status = fence_is_signaled(sync_file->fence);
- if (status) - return POLLIN; + if (!status) + return 0; + if (status < 0) return POLLERR; - return 0; + + return POLLIN; }
static long sync_file_ioctl_merge(struct sync_file *sync_file, 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 sync_file { 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);