From 0cf4daee31d88086cf3508d1d8d1f4e451c27906 Mon Sep 17 00:00:00 2001 From: Brandon Philips Date: Fri, 28 Mar 2008 10:18:33 -0700 Subject: [PATCH] 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: Brandon Philips Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/videobuf-core.c | 46 +++++++++++++++---------------------- 1 file changed, 18 insertions(+), 28 deletions(-) diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c index 45a8cbd..848a2d0 100644 --- a/drivers/media/video/videobuf-core.c +++ b/drivers/media/video/videobuf-core.c @@ -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); @@ -180,8 +183,7 @@ 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); + spin_lock_irqsave(q->irqlock, flags); for (i = 0; i < VIDEO_MAX_FRAME; i++) { if (NULL == q->bufs[i]) continue; @@ -191,8 +193,7 @@ void videobuf_queue_cancel(struct videobuf_queue *q) wake_up_all(&q->bufs[i]->done); } } - if (q->irqlock) - spin_unlock_irqrestore(q->irqlock, flags); + spin_unlock_irqrestore(q->irqlock, flags); /* free all buffers + clear queue */ for (i = 0; i < VIDEO_MAX_FRAME; i++) { @@ -548,11 +549,9 @@ 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); + spin_lock_irqsave(q->irqlock, flags); q->ops->buf_queue(q, buf); - if (q->irqlock) - spin_unlock_irqrestore(q->irqlock, flags); + spin_unlock_irqrestore(q->irqlock, flags); } dprintk(1, "qbuf: succeded\n"); retval = 0; @@ -689,13 +688,11 @@ int videobuf_streamon(struct videobuf_queue *q) if (q->streaming) goto done; q->streaming = 1; - if (q->irqlock) - spin_lock_irqsave(q->irqlock, flags); + 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); + spin_unlock_irqrestore(q->irqlock, flags); wake_up_interruptible_sync(&q->wait); done: @@ -751,11 +748,9 @@ static ssize_t videobuf_read_zerocopy(struct videobuf_queue *q, goto done; /* start capture & wait */ - 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); + spin_unlock_irqrestore(q->irqlock, flags); retval = videobuf_waiton(q->read_buf, 0, 0); if (0 == retval) { CALL(q, sync, q, q->read_buf); @@ -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); + spin_unlock_irqrestore(q->irqlock, flags); + q->read_off = 0; } @@ -887,12 +881,10 @@ 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); + 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); + spin_unlock_irqrestore(q->irqlock, flags); q->reading = 1; return 0; } @@ -1004,11 +996,9 @@ 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); + spin_lock_irqsave(q->irqlock, flags); q->ops->buf_queue(q, q->read_buf); - if (q->irqlock) - spin_unlock_irqrestore(q->irqlock, flags); + spin_unlock_irqrestore(q->irqlock, flags); q->read_buf = NULL; } if (retval < 0) -- 2.7.4