From 6c9de52884aeafb05a935467c3a2c05a2d445ab7 Mon Sep 17 00:00:00 2001 From: Andy Walls Date: Wed, 3 Sep 2008 17:11:54 -0300 Subject: [PATCH] V4L/DVB (8769): cx18: Simplify queue flush logic to prevent oops in cx18_flush_queues() cx18: Simplify queue flush logic to prevent oops in cx18_flush_queues(). If accounting of a queue is in error, logic borrowed from ivtv will cause an oops when flushing the queues for a stream. This change greatly simplifies the queue flush logic, and sets the queue back to sane defaults on a flush. Signed-off-by: Andy Walls Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/cx18/cx18-queue.c | 98 ++++----------------------- 1 file changed, 15 insertions(+), 83 deletions(-) diff --git a/drivers/media/video/cx18/cx18-queue.c b/drivers/media/video/cx18/cx18-queue.c index a31da49f91..dbe792ac30 100644 --- a/drivers/media/video/cx18/cx18-queue.c +++ b/drivers/media/video/cx18/cx18-queue.c @@ -110,99 +110,31 @@ struct cx18_buffer *cx18_queue_get_buf_irq(struct cx18_stream *s, u32 id, return NULL; } -static void cx18_queue_move_buf(struct cx18_stream *s, struct cx18_queue *from, - struct cx18_queue *to, int clear, int full) -{ - struct cx18_buffer *buf = - list_entry(from->list.next, struct cx18_buffer, list); - - list_move_tail(from->list.next, &to->list); - from->buffers--; - from->length -= s->buf_size; - from->bytesused -= buf->bytesused - buf->readpos; - /* special handling for q_free */ - if (clear) - buf->bytesused = buf->readpos = buf->b_flags = 0; - else if (full) { - /* special handling for stolen buffers, assume - all bytes are used. */ - buf->bytesused = s->buf_size; - buf->readpos = buf->b_flags = 0; - } - to->buffers++; - to->length += s->buf_size; - to->bytesused += buf->bytesused - buf->readpos; -} - -/* Move 'needed_bytes' worth of buffers from queue 'from' into queue 'to'. - If 'needed_bytes' == 0, then move all buffers from 'from' into 'to'. - If 'steal' != NULL, then buffers may also taken from that queue if - needed. - - The buffer is automatically cleared if it goes to the free queue. It is - also cleared if buffers need to be taken from the 'steal' queue and - the 'from' queue is the free queue. - - When 'from' is q_free, then needed_bytes is compared to the total - available buffer length, otherwise needed_bytes is compared to the - bytesused value. For the 'steal' queue the total available buffer - length is always used. - - -ENOMEM is returned if the buffers could not be obtained, 0 if all - buffers where obtained from the 'from' list and if non-zero then - the number of stolen buffers is returned. */ -static int cx18_queue_move(struct cx18_stream *s, struct cx18_queue *from, - struct cx18_queue *steal, struct cx18_queue *to, - int needed_bytes) +/* Move all buffers of a queue to q_free, while flushing the buffers */ +static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q) { unsigned long flags; - int rc = 0; - int from_free = from == &s->q_free; - int to_free = to == &s->q_free; - int bytes_available; - - spin_lock_irqsave(&s->qlock, flags); - if (needed_bytes == 0) { - from_free = 1; - needed_bytes = from->length; - } - - bytes_available = from_free ? from->length : from->bytesused; - bytes_available += steal ? steal->length : 0; + struct cx18_buffer *buf; - if (bytes_available < needed_bytes) { - spin_unlock_irqrestore(&s->qlock, flags); - return -ENOMEM; - } - if (from_free) { - u32 old_length = to->length; + if (q == &s->q_free) + return; - while (to->length - old_length < needed_bytes) { - if (list_empty(&from->list)) - from = steal; - if (from == steal) - rc++; /* keep track of 'stolen' buffers */ - cx18_queue_move_buf(s, from, to, 1, 0); - } - } else { - u32 old_bytesused = to->bytesused; - - while (to->bytesused - old_bytesused < needed_bytes) { - if (list_empty(&from->list)) - from = steal; - if (from == steal) - rc++; /* keep track of 'stolen' buffers */ - cx18_queue_move_buf(s, from, to, to_free, rc); - } + spin_lock_irqsave(&s->qlock, flags); + while (!list_empty(&q->list)) { + 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++; + s->q_free.length += s->buf_size; } + cx18_queue_init(q); spin_unlock_irqrestore(&s->qlock, flags); - return rc; } void cx18_flush_queues(struct cx18_stream *s) { - cx18_queue_move(s, &s->q_io, NULL, &s->q_free, 0); - cx18_queue_move(s, &s->q_full, NULL, &s->q_free, 0); + cx18_queue_flush(s, &s->q_io); + cx18_queue_flush(s, &s->q_full); } int cx18_stream_alloc(struct cx18_stream *s) -- 2.39.5