cx18: Convert cx18_queue buffers member to atomic_t

From: Andy Walls <awalls@radix.net>

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.

Priority: normal

Signed-off-by: Andy Walls <awalls@radix.net>

1 files changed, 6 insertions, 6 deletions

diff --git a/linux/drivers/media/video/cx18/cx18-queue.c b/linux/drivers/media/video/cx18/cx18-queue.c
index 902fbd118..78a0f04be 100644
--- a/linux/drivers/media/video/cx18/cx18-queue.c
+++ b/linux/drivers/media/video/cx18/cx18-queue.c
@@ -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);