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d="scan'208";a="917443074" Received: from skotini-mobl.amr.corp.intel.com (HELO [10.209.169.137]) ([10.209.169.137]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Sep 2023 07:02:05 -0700 Message-ID: Date: Tue, 12 Sep 2023 10:02:04 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.15.0 Subject: Re: [PATCH v4 01/11] ASoC: SOF: core: add 'no_wq' probe and remove callbacks To: =?UTF-8?Q?P=c3=a9ter_Ujfalusi?= , Kai Vehmanen , Maarten Lankhorst Cc: alsa-devel@alsa-project.org, Jaroslav Kysela , Takashi Iwai , Cezary Rojewski , Liam Girdwood , Bard Liao , Ranjani Sridharan , Mark Brown , Daniel Baluta , linux-kernel@vger.kernel.org, sound-open-firmware@alsa-project.org References: <20230830153652.217855-1-maarten.lankhorst@linux.intel.com> <20230830153652.217855-2-maarten.lankhorst@linux.intel.com> <4252a4dc-0cf3-4ff2-aa55-c03e56345276@linux.intel.com> <4d84a799-c07e-e917-7c82-2f24456e3ac2@linux.intel.com> <6d39eac7-06c7-45f0-0318-72be1753641f@linux.intel.com> <34d34e99-c6a3-2d08-2c4b-c548b6b87e9a@linux.intel.com> Content-Language: en-US From: Pierre-Louis Bossart In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Message-ID-Hash: 6OTCY24JXPASWFIFSEGMJXYDVBRPHYW4 X-Message-ID-Hash: 6OTCY24JXPASWFIFSEGMJXYDVBRPHYW4 X-MailFrom: pierre-louis.bossart@linux.intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 9/12/23 02:10, Péter Ujfalusi wrote: > > > On 12/09/2023 03:25, Pierre-Louis Bossart wrote: >> >> >>> What we have atm: >>> snd_sof_probe - might be called from wq >>> snd_sof_remove - might be called from wq (cleans up the snd_sof_probe >>> step) >> >> I don't think it's correct, snd_sof_remove cannot be called from a wq. >> The device core knows nothing about workqueues. > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/sof/core.c#n328 > > it is called on the error path of sof_probe_continue(), which can be run > in a workque. > >>> We want a callbacks for hardware/device probing, right, split the >>> snd_sof_probe (and remove) to be able to support a sane level of >>> deferred probing support. >>> >>> With that in mind: >>> snd_sof_device_probe - Not called from wq (to handle deferred probing) >>> snd_sof_probe - might be called from wq >>> >>> snd_sof_remove - might be called from wq (cleans up the snd_sof_probe >>> step) >>> snd_sof_device_remove - Not called from wq (to up the >>> snd_sof_device_probe step) >>> >>> Naming option: s/device/hardware >> >> I like the 'device' hint since it's directly related to the device (or >> subsystem) callbacks. >> >>> However, I think the snd_sof_device_remove itself is redundant and we >>> might not need it at all as in case we have wq and there is a failure in >>> there we do want to release resources as much as possible. The module >>> will be kept loaded (no deferred handling in wq) and that might block >>> PM, other devices to behave correctly. Iow, if the wq has failure we >>> should do a cleanup to the best effort to reach a level like the driver >>> is not even loaded. >> >> If we have a failure in a workqueue used for probe, then we have to >> clean-up everything since nothing in the device core will do so for us. > > Yes, this makes the snd_sof_device_remove() redundant or at least the > definition of it is no longer a mirror of snd_sof_device_probe(): > > snd_sof_device_remove - might be called from wq (cleans up the > snd_sof_device_probe step) > > Any failure in sof_probe_continue() should execute the > snd_sof_device_remove(), snd_sof_remove() is only involved after the > snd_sof_probe() have returned with success. > > I think this makes actually makes sense and it is well defined. > On module remove we need to take into account the case when we have > failed in wq similarly as we do currently (the resources have been freed > up already). Agree, I stand corrected, thanks Peter.