From b04bce476c57ac844962462ee4c813c44fa942cf Mon Sep 17 00:00:00 2001 From: Andy Walls Date: Fri, 22 Aug 2008 21:03:11 -0300 Subject: [PATCH] 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 Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/cx18/cx18-driver.h | 2 +- drivers/media/video/cx18/cx18-fileops.c | 4 ++-- drivers/media/video/cx18/cx18-ioctl.c | 3 ++- drivers/media/video/cx18/cx18-queue.c | 12 ++++++------ 4 files changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/media/video/cx18/cx18-driver.h b/drivers/media/video/cx18/cx18-driver.h index 28c490b..8812a5e 100644 --- a/drivers/media/video/cx18/cx18-driver.h +++ b/drivers/media/video/cx18/cx18-driver.h @@ -216,7 +216,7 @@ struct cx18_buffer { struct cx18_queue { struct list_head list; - u32 buffers; + atomic_t buffers; u32 bytesused; }; diff --git a/drivers/media/video/cx18/cx18-fileops.c b/drivers/media/video/cx18/cx18-fileops.c index 2fdbfb9..eb0144f 100644 --- a/drivers/media/video/cx18/cx18-fileops.c +++ b/drivers/media/video/cx18/cx18-fileops.c @@ -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; diff --git a/drivers/media/video/cx18/cx18-ioctl.c b/drivers/media/video/cx18/cx18-ioctl.c index a7f8396..5325c7a 100644 --- a/drivers/media/video/cx18/cx18-ioctl.c +++ b/drivers/media/video/cx18/cx18-ioctl.c @@ -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", diff --git a/drivers/media/video/cx18/cx18-queue.c b/drivers/media/video/cx18/cx18-queue.c index 4f3bd43..a33ba04 100644 --- a/drivers/media/video/cx18/cx18-queue.c +++ b/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); -- 2.7.4