linux-kernel - Re: [PATCH] ALSA: sh: aica: Remove deprecated create

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Date:	Tue, 07 Jun 2016 11:24:38 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	"Bhaktipriya Shridhar" <bhaktipriya96@...il.com>
Cc:	"Jaroslav Kysela" <perex@...ex.cz>, <alsa-devel@...a-project.org>,
	"Tejun Heo" <tj@...nel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: sh: aica: Remove deprecated create_workqueue

On Tue, 07 Jun 2016 05:41:48 +0200,
Bhaktipriya Shridhar wrote:
> 
> System workqueues have been able to handle high level of concurrency
> for a long time now and there's no reason to use dedicated workqueues
> just to gain concurrency. Since aica_queue for AICA sound
> driver has workitem dreamcastcard->spu_dma_work (maps to run_spu_dma)
> which is involved in aica dma transfers and is not being used on a memory
> reclaim path, dedicated aica_queue has been replaced with the
> use of system_wq.
> 
> Unlike a dedicated per-cpu workqueue created with create_workqueue(),
> system_wq allows multiple work items to overlap executions even on
> the same CPU; however, a per-cpu workqueue doesn't have any CPU
> locality or global ordering guarantees unless the target CPU is
> explicitly specified and thus the increase of local concurrency
> shouldn't make any difference.
> 
> Since the work items could be pending, flush_work() has been used in
> snd_aicapcm_pcm_close() to ensure that there is no pending task while
> disconnecting the driver.
> 
> Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@...il.com>

Applied, thanks.


Takashi

> ---
>  sound/sh/aica.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/sound/sh/aica.c b/sound/sh/aica.c
> index ad3d9ae..fbbc252 100644
> --- a/sound/sh/aica.c
> +++ b/sound/sh/aica.c
> @@ -63,9 +63,6 @@ MODULE_PARM_DESC(id, "ID string for " CARD_NAME " soundcard.");
>  module_param(enable, bool, 0644);
>  MODULE_PARM_DESC(enable, "Enable " CARD_NAME " soundcard.");
> 
> -/* Use workqueue */
> -static struct workqueue_struct *aica_queue;
> -
>  /* Simple platform device */
>  static struct platform_device *pd;
>  static struct resource aica_memory_space[2] = {
> @@ -327,7 +324,7 @@ static void aica_period_elapsed(unsigned long timer_var)
>  		dreamcastcard->current_period = play_period;
>  	if (unlikely(dreamcastcard->dma_check == 0))
>  		dreamcastcard->dma_check = 1;
> -	queue_work(aica_queue, &(dreamcastcard->spu_dma_work));
> +	schedule_work(&(dreamcastcard->spu_dma_work));
>  }
> 
>  static void spu_begin_dma(struct snd_pcm_substream *substream)
> @@ -337,7 +334,7 @@ static void spu_begin_dma(struct snd_pcm_substream *substream)
>  	runtime = substream->runtime;
>  	dreamcastcard = substream->pcm->private_data;
>  	/*get the queue to do the work */
> -	queue_work(aica_queue, &(dreamcastcard->spu_dma_work));
> +	schedule_work(&(dreamcastcard->spu_dma_work));
>  	/* Timer may already be running */
>  	if (unlikely(dreamcastcard->timer.data)) {
>  		mod_timer(&dreamcastcard->timer, jiffies + 4);
> @@ -381,7 +378,7 @@ static int snd_aicapcm_pcm_close(struct snd_pcm_substream
>  				 *substream)
>  {
>  	struct snd_card_aica *dreamcastcard = substream->pcm->private_data;
> -	flush_workqueue(aica_queue);
> +	flush_work(&(dreamcastcard->spu_dma_work));
>  	if (dreamcastcard->timer.data)
>  		del_timer(&dreamcastcard->timer);
>  	kfree(dreamcastcard->channel);
> @@ -633,9 +630,6 @@ static int snd_aica_probe(struct platform_device *devptr)
>  	if (unlikely(err < 0))
>  		goto freedreamcast;
>  	platform_set_drvdata(devptr, dreamcastcard);
> -	aica_queue = create_workqueue(CARD_NAME);
> -	if (unlikely(!aica_queue))
> -		goto freedreamcast;
>  	snd_printk
>  	    ("ALSA Driver for Yamaha AICA Super Intelligent Sound Processor\n");
>  	return 0;
> @@ -671,10 +665,6 @@ static int __init aica_init(void)
> 
>  static void __exit aica_exit(void)
>  {
> -	/* Destroy the aica kernel thread            *
> -	 * being extra cautious to check if it exists*/
> -	if (likely(aica_queue))
> -		destroy_workqueue(aica_queue);
>  	platform_device_unregister(pd);
>  	platform_driver_unregister(&snd_aica_driver);
>  	/* Kill any sound still playing and reset ARM7 to safe state */
> --
> 2.1.4
> 
>