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SubjectRe: [alsa-devel] [PATCH] ASoC: core: Invoke pcm_new() for all DAI-link
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.


thanks,

Takashi

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