At Thu, 11 Jul 2013 22:13:35 +0800, Ming Lei wrote:

On Thu, Jul 11, 2013 at 9:50 PM, Takashi Iwai tiwai@suse.de wrote:

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At Thu, 11 Jul 2013 17:08:30 +0400, Sergei Shtylyov wrote:

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On 11-07-2013 13:06, Ming Lei wrote:

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Complete() will be run with interrupt enabled, so change to spin_lock_irqsave().

Changelog doesn't match the patch.

Yep, but moreover...

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Cc: Jaroslav Kysela perex@perex.cz Cc: Takashi Iwai tiwai@suse.de Cc: alsa-devel@alsa-project.org Signed-off-by: Ming Lei ming.lei@canonical.com

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sound/usb/usx2y/usbusx2yaudio.c | 4 ++++ 1 file changed, 4 insertions(+)

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diff --git a/sound/usb/usx2y/usbusx2yaudio.c b/sound/usb/usx2y/usbusx2yaudio.c index 4967fe9..e2ee893 100644 --- a/sound/usb/usx2y/usbusx2yaudio.c +++ b/sound/usb/usx2y/usbusx2yaudio.c @@ -273,7 +273,11 @@ static void usX2Y_clients_stop(struct usX2Ydev *usX2Y) struct snd_usX2Y_substream *subs = usX2Y->subs[s]; if (subs) { if (atomic_read(&subs->state) >= state_PRERUNNING) {

•                       unsigned long flags;
  

•                       local_irq_save(flags);
                        snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN);
  

•                       local_irq_restore(flags);
                }
  

... actually this snd_pcm_stop() call should have been covered by snd_pcm_stream_lock(). Maybe it'd be enough to have a single patch together with the change, i.e. wrapping with snd_pcm_stream_lock_irqsave().

Please use snd_pcm_stream_lock_irqsave() so that I can avoid sending out similar patch later, :-)

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I'll prepare the patch for 3.11 independently from your patch series, so please drop this one.

OK, thanks for dealing with that.

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BTW, the word "cleanup" in the subject is inappropriate. This is rather a fix together with the core change.

It is a cleanup since the patchset only addresses lock problem which is caused by the tasklet conversion.

Well, the conversion to irqsave() is needed for the future drop of irq_save() in the caller, right? Then this isn't a cleanup but a preparation for movement ahead.

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And, I wonder whether we can take a safer approach. When the caller condition changed, we often introduced either a different ops (e.g. ioctl case) or a flag for the new condition, at least during the transition period.

Interrupt is't enabled until all current drivers are cleaned up, so it is really safe, please see patch [2].

OK.

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Last but not least, is a conversion to tasklet really preferred? tasklet is rather an obsoleted infrastructure nowadays, and people don't recommend to use it any longer, AFAIK.

We discussed the problem in the below link previously[1], Steven and Thomas suggested to use threaded irq handler, but which may degrade USB mass storage performance, so we have to take tasklet now until we rewrite transport part of USB mass storage driver.

Also the conversion[2] has avoided the tasklet spin lock problem already.

OK, good to know.

thanks,

Takashi

[1], http://marc.info/?t=137079119200001&r=1&w=2 [2], http://marc.info/?l=linux-usb&m=137286326726326&w=2

Thanks,

Ming Lei