From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1526577051; cv=none; d=google.com; s=arc-20160816; b=cS27OM10Kn7B6YBve7QM+yBG8zzEGDyM3Ou5HqW3GPC/9ak3MmSOJEoXNP3hH2FZnw Es4TjfWmEE/EOanInPCcblx+65mES4O1Bo1JBy1l0v4aTlv2lV+jLxIOXyhXMN9NAPgl bu92OdIAO482Dk7AYchFV92eKgG1gNis0Sz5eu3PpSz/i+cXSzeN0je3l9PalYYjxIXK 09TLXjG5MU4MhudNWl+hfAx27OHlu/kIosNrVdLvNRh5w/y7yuLQQj7YMg26BVfSoGuP U8oBKWylmqAJ+2MGKjoEKmAiYWVafnLeAqM0eVgVC4xRbKB199B2KWKM31FG+6Wj7+Jb jPNQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject :dkim-signature:arc-authentication-results; bh=gvGXpNY9l6BhV7N/bSeE7mefgT7777YK9wsrHMGyLP8=; b=qiNAxmLgxyoOr01svNKxVdcXoGqOuJ02sAHWBsgfyasVBvzC9QRzm7HdbowJsopk0Q q8Xk499chPsvCq93NSmjLZJsOEi+zeOVS8hUrUVtLSg2bIzxFVtpWGXAyH/wmuAVE3XN CbajnzfDM0Y73zwvHbLO4RDMONxUoZG32JXw3gJJNakOiLvZaZ/pIByDUdEiVlAzxI65 UdqE271EgBcvg9GMrmaT/MABQhjP4Z4PCoOq9ylnm4DdeYPnEaeMHyKrVifEdMlthhse 6ngaz0/6Erv/g0ydXA4DSAjQZAJgDgk7+VmLfZwWMPyQDbPaWgJl9bos1xCeHa1uPB08 A3zQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=TbN2fPok; spf=pass (google.com: domain of srinivas.kandagatla@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=srinivas.kandagatla@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=TbN2fPok; spf=pass (google.com: domain of srinivas.kandagatla@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=srinivas.kandagatla@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org X-Google-Smtp-Source: AB8JxZqeubQ5Acz0r73HF6dmaIBJz148sXxtzggejJWFMOtuSt4s77HmCMto7ANvH+y/8qZE/LpBSw== Subject: Re: [PATCH v8 09/24] ASoC: qdsp6: q6afe: Add q6afe driver To: Mark Brown Cc: andy.gross@linaro.org, linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org, robh+dt@kernel.org, bgoswami@codeaurora.org, gregkh@linuxfoundation.org, david.brown@linaro.org, mark.rutland@arm.com, lgirdwood@gmail.com, plai@codeaurora.org, tiwai@suse.com, perex@perex.cz, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rohkumar@qti.qualcomm.com, spatakok@qti.qualcomm.com References: <20180509125635.5653-1-srinivas.kandagatla@linaro.org> <20180509125635.5653-10-srinivas.kandagatla@linaro.org> <20180517065544.GO20254@sirena.org.uk> From: Srinivas Kandagatla Message-ID: <507b8b76-0846-a492-73e6-782b9953bc36@linaro.org> Date: Thu, 17 May 2018 18:10:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20180517065544.GO20254@sirena.org.uk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599991553144563990?= X-GMAIL-MSGID: =?utf-8?q?1600732058650695478?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Thanks for the review. On 17/05/18 07:55, Mark Brown wrote: > On Wed, May 09, 2018 at 01:56:20PM +0100, Srinivas Kandagatla wrote: > >> +static struct q6afe_port *afe_find_port(struct q6afe *afe, int token) >> +{ >> + struct q6afe_port *p = NULL; >> + struct q6afe_port *ret = NULL; >> + unsigned long flags; >> + >> + spin_lock_irqsave(&afe->port_list_lock, flags); >> + list_for_each_entry(p, &afe->port_list, node) >> + if (p->token == token) { >> + ret = p; >> + break; >> + } >> + >> + spin_unlock_irqrestore(&afe->port_list_lock, flags); >> + return ret; > > This lock only protects the list, it does nothing to ensure that the > port we look up is still valid by the time we return to the caller. > That means we won't crash during list traversal but does nothing to > ensure we won't crash immediately afterwards if the port is deallocated > just after we look it up. What stops that happening? Each port is allocated and de-allocated in dai probe and remove calls respectively. Lets say... So for this case to happen the dai has to be removed (unload module) at the same time when the interrupt callback happens due to delayed response from previous commands. This case would be almost impossible because all the calls to afe service are synchronous with timeouts, if any of the previous calls times out the respective caller would get an error, this should prevent him from unloading the module in the first place. thanks, srini >