From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: alsa-devel@alsa-project.org,
Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
open list <linux-kernel@vger.kernel.org>,
Sameer Pujar <spujar@nvidia.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Takashi Iwai <tiwai@suse.com>,
vkoul@kernel.org, broonie@kernel.org,
Gyeongtaek Lee <gt82.lee@samsung.com>,
Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Subject: Re: [RFC PATCH v3 05/13] ASoC: soc-pcm: align BE 'atomicity' with that of the FE
Date: Fri, 15 Oct 2021 12:08:48 -0500 [thread overview]
Message-ID: <c0803288-efb1-aaeb-218f-e1a6ba87abd7@linux.intel.com> (raw)
In-Reply-To: <s5hmtnateeo.wl-tiwai@suse.de>
>> I have not been able to figure out when you need
>> a) the pcm_mutex only
>> b) the fe stream lock only
>> c) both pcm_mutex and fe stream lock
>
> The pcm_mutex is needed for every sleepable function that treat DPCM
> FE link, but the mutex is taken only at the upper level, i.e. the
> top-most caller like PCM ops FE itself or the DAPM calls.
>
> That said, pcm_mutex is the top-most protection of BE links in FE.
> But, there is a code path where a mutex can't be used, and that's the
> FE and BE trigger. For protecting against this, the FE stream lock is
> taken only at the placing both adding and deleting a BE *in addition*.
> At those places, both pcm_mutex and FE stream lock are taken.
>
> BE stream lock is taken in addition below the above mutex and FE
> locks.
Thanks Takashi, now I get the idea. Makes sense indeed. I'll make sure
to add this explanation to the commit message/cover so that it's not lost.
I added your three patches to my tests, so far so good, code is that
https://github.com/thesofproject/linux/pull/3215
Thanks and have a nice week-end.
-Pierre
next prev parent reply other threads:[~2021-10-15 17:08 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20211013143050.244444-1-pierre-louis.bossart@linux.intel.com>
2021-10-13 14:30 ` [RFC PATCH v3 01/13] ASoC: soc-pcm: remove snd_soc_dpcm_fe_can_update() Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 02/13] ASoC: soc-pcm: don't export local functions, use static Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 03/13] ASoC: soc-pcm: use proper indentation on 'continue' Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 04/13] ASoC: soc-pcm: introduce snd_soc_dpcm_fe_lock_irq/unlock_irq() Pierre-Louis Bossart
2021-10-15 6:24 ` Sameer Pujar
2021-10-15 12:24 ` Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 05/13] ASoC: soc-pcm: align BE 'atomicity' with that of the FE Pierre-Louis Bossart
2021-10-15 6:24 ` Sameer Pujar
2021-10-15 7:39 ` Takashi Iwai
2021-10-15 11:22 ` Pierre-Louis Bossart
2021-10-15 12:04 ` Pierre-Louis Bossart
2021-10-15 15:38 ` Takashi Iwai
2021-10-15 16:22 ` Pierre-Louis Bossart
2021-10-15 16:56 ` Takashi Iwai
2021-10-15 17:08 ` Pierre-Louis Bossart [this message]
2021-10-13 14:30 ` [RFC PATCH v3 06/13] ASoC: soc-pcm: remove dpcm spin_lock, use PCM stream lock Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 07/13] ASoC: soc-pcm: protect for_each_dpcm_be() loops Pierre-Louis Bossart
2021-10-15 6:24 ` Sameer Pujar
2021-10-15 11:02 ` Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 08/13] ASoC: soc-compress: " Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 09/13] ASoC: sh: rcar: " Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 10/13] ASoC: fsl: asrc_dma: " Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 11/13] ASoC: soc-pcm: serialize BE triggers Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 12/13] ASoC: soc-pcm: test refcount before triggering Pierre-Louis Bossart
2021-10-13 14:30 ` [RFC PATCH v3 13/13] ASoC: soc-pcm: fix BE handling of PAUSE_RELEASE Pierre-Louis Bossart
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