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Commit 0cf4daee authored by Brandon Philips's avatar Brandon Philips Committed by Mauro Carvalho Chehab
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V4L/DVB (7562): videobuf: Require spinlocks for all videobuf users 



A spinlock is necessary for queue_cancel to work with every driver in the tree.
Otherwise a race exists between IRQ handlers removing buffers from the queue
and queue_cancel invalidating the queue.

Signed-off-by: default avatarBrandon Philips <bphilips@suse.de>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent aa9479ed

drivers/media/video/videobuf-core.c

+18 −28
Original line number Diff line number Diff line
@@ -123,6 +123,9 @@ void videobuf_queue_core_init(struct videobuf_queue *q, 
	BUG_ON(!q->ops->buf_queue);

	BUG_ON(!q->ops->buf_release);



	/* Lock is mandatory for queue_cancel to work */

	BUG_ON(!irqlock);



	/* Having implementations for abstract methods are mandatory */

	BUG_ON(!q->int_ops);
@@ -180,7 +183,6 @@ void videobuf_queue_cancel(struct videobuf_queue *q) 
	wake_up_interruptible_sync(&q->wait);



	/* remove queued buffers from list */

	if (q->irqlock)

	spin_lock_irqsave(q->irqlock, flags);

	for (i = 0; i < VIDEO_MAX_FRAME; i++) {

		if (NULL == q->bufs[i])
@@ -191,7 +193,6 @@ void videobuf_queue_cancel(struct videobuf_queue *q) 
			wake_up_all(&q->bufs[i]->done);

		}

	}

	if (q->irqlock)

	spin_unlock_irqrestore(q->irqlock, flags);



	/* free all buffers + clear queue */
@@ -548,10 +549,8 @@ int videobuf_qbuf(struct videobuf_queue *q, 


	list_add_tail(&buf->stream, &q->stream);

	if (q->streaming) {

		if (q->irqlock)

		spin_lock_irqsave(q->irqlock, flags);

		q->ops->buf_queue(q, buf);

		if (q->irqlock)

		spin_unlock_irqrestore(q->irqlock, flags);

	}

	dprintk(1, "qbuf: succeded\n");
@@ -689,12 +688,10 @@ int videobuf_streamon(struct videobuf_queue *q) 
	if (q->streaming)

		goto done;

	q->streaming = 1;

	if (q->irqlock)

	spin_lock_irqsave(q->irqlock, flags);

	list_for_each_entry(buf, &q->stream, stream)

		if (buf->state == VIDEOBUF_PREPARED)

			q->ops->buf_queue(q, buf);

	if (q->irqlock)

	spin_unlock_irqrestore(q->irqlock, flags);



	wake_up_interruptible_sync(&q->wait);
@@ -751,10 +748,8 @@ static ssize_t videobuf_read_zerocopy(struct videobuf_queue *q, 
		goto done;



	/* start capture & wait */

	if (q->irqlock)

	spin_lock_irqsave(q->irqlock, flags);

	q->ops->buf_queue(q, q->read_buf);

	if (q->irqlock)

	spin_unlock_irqrestore(q->irqlock, flags);

	retval = videobuf_waiton(q->read_buf, 0, 0);

	if (0 == retval) {
@@ -816,12 +811,11 @@ ssize_t videobuf_read_one(struct videobuf_queue *q, 
			q->read_buf = NULL;

			goto done;

		}

		if (q->irqlock)

			spin_lock_irqsave(q->irqlock, flags);



		spin_lock_irqsave(q->irqlock, flags);

		q->ops->buf_queue(q, q->read_buf);

		if (q->irqlock)

		spin_unlock_irqrestore(q->irqlock, flags);



		q->read_off = 0;

	}
@@ -887,11 +881,9 @@ static int __videobuf_read_start(struct videobuf_queue *q) 
			return err;

		list_add_tail(&q->bufs[i]->stream, &q->stream);

	}

	if (q->irqlock)

	spin_lock_irqsave(q->irqlock, flags);

	for (i = 0; i < count; i++)

		q->ops->buf_queue(q, q->bufs[i]);

	if (q->irqlock)

	spin_unlock_irqrestore(q->irqlock, flags);

	q->reading = 1;

	return 0;
@@ -1004,10 +996,8 @@ ssize_t videobuf_read_stream(struct videobuf_queue *q, 
		if (q->read_off == q->read_buf->size) {

			list_add_tail(&q->read_buf->stream,

				      &q->stream);

			if (q->irqlock)

			spin_lock_irqsave(q->irqlock, flags);

			q->ops->buf_queue(q, q->read_buf);

			if (q->irqlock)

			spin_unlock_irqrestore(q->irqlock, flags);

			q->read_buf = NULL;

		}