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: Andy Walls <awalls@radix.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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parent
59ba2b0022
commit
b04bce476c
drivers/media/video/cx18
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@ -216,7 +216,7 @@ struct cx18_buffer {
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struct cx18_queue {
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struct list_head list;
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u32 buffers;
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atomic_t buffers;
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u32 bytesused;
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};
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@ -223,7 +223,7 @@ static struct cx18_buffer *cx18_get_buffer(struct cx18_stream *s, int non_block,
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prepare_to_wait(&s->waitq, &wait, TASK_INTERRUPTIBLE);
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/* New buffers might have become available before we were added
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to the waitqueue */
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if (!s->q_full.buffers)
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if (!atomic_read(&s->q_full.buffers))
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schedule();
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finish_wait(&s->waitq, &wait);
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if (signal_pending(current)) {
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@ -509,7 +509,7 @@ unsigned int cx18_v4l2_enc_poll(struct file *filp, poll_table *wait)
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CX18_DEBUG_HI_FILE("Encoder poll\n");
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poll_wait(filp, &s->waitq, wait);
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if (s->q_full.buffers || s->q_io.buffers)
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if (atomic_read(&s->q_full.buffers) || atomic_read(&s->q_io.buffers))
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return POLLIN | POLLRDNORM;
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if (eof)
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return POLLHUP;
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@ -731,7 +731,8 @@ static int cx18_log_status(struct file *file, void *fh)
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continue;
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CX18_INFO("Stream %s: status 0x%04lx, %d%% of %d KiB (%d buffers) in use\n",
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s->name, s->s_flags,
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(s->buffers - s->q_free.buffers) * 100 / s->buffers,
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(s->buffers - atomic_read(&s->q_free.buffers))
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* 100 / s->buffers,
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(s->buffers * s->buf_size) / 1024, s->buffers);
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}
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CX18_INFO("Read MPEG/VBI: %lld/%lld bytes\n",
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@ -37,7 +37,7 @@ void cx18_buf_swap(struct cx18_buffer *buf)
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void cx18_queue_init(struct cx18_queue *q)
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{
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INIT_LIST_HEAD(&q->list);
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q->buffers = 0;
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atomic_set(&q->buffers, 0);
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q->bytesused = 0;
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}
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@ -54,7 +54,7 @@ void cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
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}
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spin_lock_irqsave(&s->qlock, flags);
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list_add_tail(&buf->list, &q->list);
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q->buffers++;
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atomic_inc(&q->buffers);
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q->bytesused += buf->bytesused - buf->readpos;
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spin_unlock_irqrestore(&s->qlock, flags);
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}
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@ -68,7 +68,7 @@ struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
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if (!list_empty(&q->list)) {
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buf = list_entry(q->list.next, struct cx18_buffer, list);
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list_del_init(q->list.next);
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q->buffers--;
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atomic_dec(&q->buffers);
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q->bytesused -= buf->bytesused - buf->readpos;
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}
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spin_unlock_irqrestore(&s->qlock, flags);
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@ -92,8 +92,8 @@ struct cx18_buffer *cx18_queue_get_buf_irq(struct cx18_stream *s, u32 id,
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/* the transport buffers are handled differently,
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they are not moved to the full queue */
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if (s->type != CX18_ENC_STREAM_TYPE_TS) {
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s->q_free.buffers--;
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s->q_full.buffers++;
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atomic_dec(&s->q_free.buffers);
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atomic_inc(&s->q_full.buffers);
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s->q_full.bytesused += buf->bytesused;
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list_move_tail(&buf->list, &s->q_full.list);
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}
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@ -119,7 +119,7 @@ static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q)
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buf = list_entry(q->list.next, struct cx18_buffer, list);
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list_move_tail(q->list.next, &s->q_free.list);
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buf->bytesused = buf->readpos = buf->b_flags = 0;
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s->q_free.buffers++;
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atomic_inc(&s->q_free.buffers);
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}
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cx18_queue_init(q);
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spin_unlock_irqrestore(&s->qlock, flags);
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