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Date: Mon, 7 Jun 2010 15:00:48 +0200
From: Richard Zidlicky <rz@...ux-m68k.org>
To: Jiri Slaby <jirislaby@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 2.6.34] schedule inside spin_lock_irqsave
On Sun, Jun 06, 2010 at 07:51:56PM +0200, Jiri Slaby wrote:
> On 06/06/2010 02:43 PM, Richard Zidlicky wrote:
> > Hi,
> >
> > I have done a minimaly invasive patch for the stable 2.6.34 kernel and stress-tested
> > it for many hours, definitely seems to improve the behaviour.
> >
> > I have left out your beautification suggestion for now, want to do more playing with
> > other aspects of the driver. There still seem to be issues when the device is unplugged
> > while in use and such.
> >
> > --- linux-2.6.34/drivers/media/dvb/siano/smscoreapi.c.rz 2010-06-03 21:58:11.000000000 +0200
> > +++ linux-2.6.34/drivers/media/dvb/siano/smscoreapi.c 2010-06-04 23:00:35.000000000 +0200
> > @@ -1100,31 +1100,26 @@
> > *
> > * @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(void)
> > {
> > struct smscore_buffer_t *cb = NULL;
> > unsigned long flags;
> >
> > - DEFINE_WAIT(wait);
> > -
> > spin_lock_irqsave(&coredev->bufferslock, flags);
>
> Sorry, maybe I'm just blind, but where is 'coredev' defined in this
> scope? You probably forgot to pass it to get_entry?
>
> How could this be compiled? Is there coredev defined globally?
good catch. I think it failed and despite a different kernel id the old module was
loaded.
Here is the new version, this time lightly tested
--- linux-2.6.34/drivers/media/dvb/siano/smscoreapi.c.rz 2010-06-03 21:58:11.000000000 +0200
+++ linux-2.6.34/drivers/media/dvb/siano/smscoreapi.c 2010-06-07 14:32:06.000000000 +0200
@@ -1100,31 +1100,26 @@
*
* @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))
- schedule();
-
- finish_wait(&coredev->buffer_mng_waitq, &wait);
-
+ if (!list_empty(&coredev->buffers)) {
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;
}
Richard
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