netdev - Re: [PATCH 45/50] sound: usb: usx2y: spin

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Date:	Thu, 11 Jul 2013 22:52:59 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, Oliver Neukum <oliver@...kum.org>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-input@...r.kernel.org, linux-bluetooth@...r.kernel.org,
	netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
	linux-media@...r.kernel.org, alsa-devel@...a-project.org,
	Jaroslav Kysela <perex@...ex.cz>
Subject: Re: [PATCH 45/50] sound: usb: usx2y: spin_lock in complete() cleanup

On Thu, Jul 11, 2013 at 10:34 PM, Takashi Iwai <tiwai@...e.de> wrote:
> At Thu, 11 Jul 2013 22:13:35 +0800,
> Ming Lei wrote:
>>
>> On Thu, Jul 11, 2013 at 9:50 PM, Takashi Iwai <tiwai@...e.de> wrote:
>> > At Thu, 11 Jul 2013 17:08:30 +0400,
>> > Sergei Shtylyov wrote:
>> >>
>> >> On 11-07-2013 13:06, Ming Lei wrote:
>> >>
>> >> > Complete() will be run with interrupt enabled, so change to
>> >> > spin_lock_irqsave().
>> >>
>> >>     Changelog doesn't match the patch.
>> >
>> > Yep, but moreover...
>> >
>> >> > Cc: Jaroslav Kysela <perex@...ex.cz>
>> >> > Cc: Takashi Iwai <tiwai@...e.de>
>> >> > Cc: alsa-devel@...a-project.org
>> >> > Signed-off-by: Ming Lei <ming.lei@...onical.com>
>> >> > ---
>> >> >   sound/usb/usx2y/usbusx2yaudio.c |    4 ++++
>> >> >   1 file changed, 4 insertions(+)
>> >>
>> >> > 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, :-)
>>
>> >
>> > I'll prepare the patch for 3.11 independently from your patch series,
>> > so please drop this one.
>>
>> OK, thanks for dealing with that.
>>
>> >
>> >
>> > 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.

Sounds more accurate, and I will change the title in next round, :-)

Thanks,
--
Ming Lei
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