Commit e2416553 authored by Gustavo Padovan's avatar Gustavo Padovan Committed by Sumit Semwal
Browse files

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: default avatarGustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarSumit 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
parent 395dec6f

drivers/dma-buf/sync_file.c

+8 −13
Original line number Diff line number Diff line
@@ -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;
@@ -291,6 +286,7 @@ static void sync_file_free(struct kref *kref) 
	struct sync_file *sync_file = container_of(kref, struct sync_file,

						     kref);



	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);
@@ -307,17 +303,16 @@ static int sync_file_release(struct inode *inode, struct file *file) 
static unsigned int sync_file_poll(struct file *file, poll_table *wait)

{

	struct sync_file *sync_file = file->private_data;

	int status;



	poll_wait(file, &sync_file->wq, wait);



	status = fence_is_signaled(sync_file->fence);

	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);

	}



	if (status)

		return POLLIN;

	if (status < 0)

		return POLLERR;

	return 0;

	return fence_is_signaled(sync_file->fence) ? POLLIN : 0;

}



static long sync_file_ioctl_merge(struct sync_file *sync_file,

include/linux/sync_file.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

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