Re: [PATCH 2.6.34] schedule inside spin_lock_irqsave

[Jiri Slaby]

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?

> -
> -	/* 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()));
>  
>  	return cb;
>  }

-- 
js
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