From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rohit Kumar Subject: Re: [alsa-devel] [PATCH] ASoC: core: Invoke pcm_new() for all DAI-link Date: Fri, 2 Nov 2018 17:36:49 +0530 Message-ID: <48c78f67-8178-2d07-e35d-2e4eca51ccbc@codeaurora.org> References: <1541075929-29323-1-git-send-email-rohitkr@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Takashi Iwai , olivier.moysan@st.com Cc: plai@codeaurora.org, bgoswami@codeaurora.org, lgirdwood@gmail.com, broonie@kernel.org, perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, rohkumar@qti.qualcomm.com, srinivas.kandagatla@linaro.org List-Id: alsa-devel@alsa-project.org On 11/2/2018 1:12 PM, Takashi Iwai wrote: > On Thu, 01 Nov 2018 13:38:49 +0100, > Rohit kumar wrote: >> Remove no_pcm check to invoke pcm_new() for backend dai-links >> too. This fixes crash in hdmi codec driver during hdmi_codec_startup() >> while accessing chmap_info struct. chmap_info struct memory is >> allocated in pcm_new() of hdmi codec driver which is not invoked >> in case of DPCM when hdmi codec driver is part of backend dai-link. >> >> Below is the crash stack: >> >> [ 61.635493] Unable to handle kernel NULL pointer dereference at virtual address 00000018 >> .. >> [ 61.666696] CM = 0, WnR = 1 >> [ 61.669778] user pgtable: 4k pages, 39-bit VAs, pgd = ffffffc0d6633000 >> [ 61.676526] [0000000000000018] *pgd=0000000153fc8003, *pud=0000000153fc8003, *pmd=0000000000000000 >> [ 61.685793] Internal error: Oops: 96000046 [#1] PREEMPT SMP >> [ 61.722955] CPU: 7 PID: 2238 Comm: aplay Not tainted 4.14.72 #21 >> .. >> [ 61.740269] PC is at hdmi_codec_startup+0x124/0x164 >> [ 61.745308] LR is at hdmi_codec_startup+0xe4/0x164 >> >> Signed-off-by: Rohit kumar > Did you check whether all drivers have no side-effect by this change? > The hdmi-codec isn't the only driver that has pcm_new ops, so we have > to make sure that such a fundamental change wouldn't bring any > regressions. > Below are the drivers calling pcm_new() other than hdmi codec driver. sound/soc/meson/axg-frddr.c sound/soc/meson/axg-toddr.c These two drivers are frontend DAI drivers and should not be impacted because of this. Other than this, pcm_new() is called from sound/soc/stm/stm32_sai_sub.c I could not get much info about this driver. However, it is just adding kcontrols in pcm_new() which uses internal private structs in get()/put(). Olivier Moysan can too confirm on this. Thanks, Rohit > thanks, > > Takashi -- Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc.is a member of the Code Aurora Forum, hosted by the Linux Foundation.