Messages in this thread | | | Subject | Re: [alsa-devel] [PATCH] ASoC: core: Invoke pcm_new() for all DAI-link | From | Rohit Kumar <> | Date | Mon, 5 Nov 2018 23:44:44 +0530 |
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Hello Arnaud,
On 11/5/2018 4:43 PM, Arnaud Pouliquen wrote: > Hello Rohit, > > On 11/2/18 1:06 PM, Rohit Kumar wrote: >> 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 <rohitkr@codeaurora.org> >>> 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. > First, i'm answering for Olivier: no regression identified for the SAI > driver, it is not a DPCM driver. > > Then i have a concern about the call of pcm_new for a no-PCM backend. > Does it make sense? In DPCM concept, the backend is not linked to the > PCM device... > > Instead, I would suggest that you add protection in HDMI_codec on > chmap_info pointer. > > The drawback would be that the control is no more available...do you > need it? I don't need chmap_info, but ELD kcontrol is also defined in pcm_new() which we need. We should probably update the driver to make it compatible with DPCM. Any suggestions? > Regards > Arnaud > >> Thanks, >> Rohit >>> thanks, >>> >>> Takashi Thanks, Rohit
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