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V4L/DVB: dvb: fix smscore_getbuffer() logic

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Drivers shouldn't sleep while holding a spinlock. A previous workaround
were to release the spinlock before callinc schedule().

This patch uses a different approach: it just waits for the
siano hardware to answer.

Signed-off-by: Richard Zidlicky <rz@linux-m68k.org>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Richard Zidlicky 2010-08-24 09:52:36 -03:00 committed by Mauro Carvalho Chehab
parent 970d14c6cc
commit 3cdadc50bb
1 changed files with 13 additions and 20 deletions
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33
drivers/media/dvb/siano/smscoreapi.c
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@ -1098,33 +1098,26 @@ EXPORT_SYMBOL_GPL(smscore_onresponse);
*
* @return pointer to descriptor on success, NULL on error.
*/
struct smscore_buffer_t *smscore_getbuffer(struct smscore_device_t *coredev)
struct smscore_buffer_t *get_entry(struct smscore_device_t *coredev)
{
struct smscore_buffer_t *cb = NULL;
unsigned long flags;
DEFINE_WAIT(wait);
spin_lock_irqsave(&coredev->bufferslock, flags);
/* This function must return a valid buffer, since the buffer list is
* finite, we check that there is an available buffer, if not, we wait
* until such buffer become available.
*/
prepare_to_wait(&coredev->buffer_mng_waitq, &wait, TASK_INTERRUPTIBLE);
if (list_empty(&coredev->buffers)) {
spin_unlock_irqrestore(&coredev->bufferslock, flags);
schedule();
spin_lock_irqsave(&coredev->bufferslock, flags);
if (!list_empty(&coredev->buffers)) {
cb = (struct smscore_buffer_t *) coredev->buffers.next;
list_del(&cb->entry);
}
finish_wait(&coredev->buffer_mng_waitq, &wait);
cb = (struct smscore_buffer_t *) coredev->buffers.next;
list_del(&cb->entry);
spin_unlock_irqrestore(&coredev->bufferslock, flags);
return cb;
}
struct smscore_buffer_t *smscore_getbuffer(struct smscore_device_t *coredev)
{
struct smscore_buffer_t *cb = NULL;
wait_event(coredev->buffer_mng_waitq, (cb = get_entry(coredev)));
return cb;
}