Commit b04bce47 authored by Andy Walls's avatar Andy Walls Committed by Mauro Carvalho Chehab
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V4L/DVB (8772): cx18: Convert cx18_queue buffers member to atomic_t 



cx18: Convert cx18_queue buffers member to atomic_t.  This allows safe
concurrent access to check if a queue has data without having to acquire the
queue spinlock.

Signed-off-by: default avatarAndy Walls <awalls@radix.net>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 59ba2b00

drivers/media/video/cx18/cx18-driver.h

+1 −1
Original line number Diff line number Diff line
@@ -216,7 +216,7 @@ struct cx18_buffer { 


struct cx18_queue {

	struct list_head list;

	u32 buffers;

	atomic_t buffers;

	u32 bytesused;

};

drivers/media/video/cx18/cx18-fileops.c

+2 −2
Original line number Diff line number Diff line
@@ -223,7 +223,7 @@ static struct cx18_buffer *cx18_get_buffer(struct cx18_stream *s, int non_block, 
		prepare_to_wait(&s->waitq, &wait, TASK_INTERRUPTIBLE);

		/* New buffers might have become available before we were added

		   to the waitqueue */

		if (!s->q_full.buffers)

		if (!atomic_read(&s->q_full.buffers))

			schedule();

		finish_wait(&s->waitq, &wait);

		if (signal_pending(current)) {
@@ -509,7 +509,7 @@ unsigned int cx18_v4l2_enc_poll(struct file *filp, poll_table *wait) 
	CX18_DEBUG_HI_FILE("Encoder poll\n");

	poll_wait(filp, &s->waitq, wait);



	if (s->q_full.buffers || s->q_io.buffers)

	if (atomic_read(&s->q_full.buffers) || atomic_read(&s->q_io.buffers))

		return POLLIN | POLLRDNORM;

	if (eof)

		return POLLHUP;

drivers/media/video/cx18/cx18-ioctl.c

+2 −1
Original line number Diff line number Diff line
@@ -731,7 +731,8 @@ static int cx18_log_status(struct file *file, void *fh) 
			continue;

		CX18_INFO("Stream %s: status 0x%04lx, %d%% of %d KiB (%d buffers) in use\n",

			  s->name, s->s_flags,

			  (s->buffers - s->q_free.buffers) * 100 / s->buffers,

			  (s->buffers - atomic_read(&s->q_free.buffers))

				* 100 / s->buffers,

			  (s->buffers * s->buf_size) / 1024, s->buffers);

	}

	CX18_INFO("Read MPEG/VBI: %lld/%lld bytes\n",

drivers/media/video/cx18/cx18-queue.c

+6 −6
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ void cx18_buf_swap(struct cx18_buffer *buf) 
void cx18_queue_init(struct cx18_queue *q)

{

	INIT_LIST_HEAD(&q->list);

	q->buffers = 0;

	atomic_set(&q->buffers, 0);

	q->bytesused = 0;

}
@@ -54,7 +54,7 @@ void cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf, 
	}

	spin_lock_irqsave(&s->qlock, flags);

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

	q->buffers++;

	atomic_inc(&q->buffers);

	q->bytesused += buf->bytesused - buf->readpos;

	spin_unlock_irqrestore(&s->qlock, flags);

}
@@ -68,7 +68,7 @@ struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q) 
	if (!list_empty(&q->list)) {

		buf = list_entry(q->list.next, struct cx18_buffer, list);

		list_del_init(q->list.next);

		q->buffers--;

		atomic_dec(&q->buffers);

		q->bytesused -= buf->bytesused - buf->readpos;

	}

	spin_unlock_irqrestore(&s->qlock, flags);
@@ -92,8 +92,8 @@ struct cx18_buffer *cx18_queue_get_buf_irq(struct cx18_stream *s, u32 id, 
		/* the transport buffers are handled differently,

		   they are not moved to the full queue */

		if (s->type != CX18_ENC_STREAM_TYPE_TS) {

			s->q_free.buffers--;

			s->q_full.buffers++;

			atomic_dec(&s->q_free.buffers);

			atomic_inc(&s->q_full.buffers);

			s->q_full.bytesused += buf->bytesused;

			list_move_tail(&buf->list, &s->q_full.list);

		}
@@ -119,7 +119,7 @@ static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q) 
		buf = list_entry(q->list.next, struct cx18_buffer, list);

		list_move_tail(q->list.next, &s->q_free.list);

		buf->bytesused = buf->readpos = buf->b_flags = 0;

		s->q_free.buffers++;

		atomic_inc(&s->q_free.buffers);

	}

	cx18_queue_init(q);

	spin_unlock_irqrestore(&s->qlock, flags);