linux-kernel - Re: [PATCH] ASoC: dapm: Check for NULL widget in dapm_update_dai

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Date:   Wed, 6 Feb 2019 10:59:55 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
CC:     Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, <alsa-devel@...a-project.org>,
        <linux-kernel@...r.kernel.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH] ASoC: dapm: Check for NULL widget in
 dapm_update_dai_unlocked

On Wed, Feb 06, 2019 at 11:22:33AM +0100, Krzysztof Kozlowski wrote:
> On Wed, 6 Feb 2019 at 11:05, Charles Keepax
> <ckeepax@...nsource.cirrus.com> wrote:
> >
> > DAIs linked to the dummy will not have an associated playback/capture
> > widget, so we need to skip the update in that case.
> >
> > Fixes: 078a85f2806f ("ASoC: dapm: Only power up active channels from a DAI")
> > Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
> > ---
> >
> > Ok so that all makes sense, this patch is probably the best fix?
> >
> > Thanks,
> > Charles
> 
> For this particular issue (NULL-pointer):
> Reported-by: Krzysztof Kozlowski <krzk@...nel.org>
> Tested-by: Krzysztof Kozlowski <krzk@...nel.org>
> 
> However now I see bug sleeping in atomic context:
> 
> [   64.000828] BUG: sleeping function called from invalid context at
> ../kernel/locking/mutex.c:908

Does this probably definitely get fixed by reverting my patch?
It's just a bit odd as this seems to be complaining about a clock
operation in i2s_trigger and I don't think my patch should have
any affect on the trigger callback. It should get run from either
the dai_link DAPM event or hw_params, neither of which should
happen in an atomic context.

> [   64.307534] the existing dependency chain (in reverse order) is:
> [   64.314985]
> [   64.314985] -> #1 (&(&pri_dai->spinlock)->rlock){....}:
> [   64.321667]        clk_mux_set_parent+0x34/0xb8
> [   64.326162]        clk_core_set_parent_nolock+0x21c/0x54c
> [   64.331535]        clk_set_parent+0x38/0x6c
> [   64.335696]        of_clk_set_defaults+0x11c/0x384
> [   64.340460]        of_clk_add_provider+0x8c/0xc8
> [   64.345054]        samsung_i2s_probe+0x484/0x64c
> [   64.349651]        platform_drv_probe+0x6c/0xa4
> [   64.354153]        really_probe+0x280/0x414
> [   64.358311]        driver_probe_device+0x78/0x1c4
> [   64.362991]        bus_for_each_drv+0x74/0xb8
> [   64.367323]        __device_attach+0xd4/0x16c
> [   64.371655]        bus_probe_device+0x88/0x90
> [   64.375988]        deferred_probe_work_func+0x4c/0xd0
> [   64.381017]        process_one_work+0x228/0x810
> [   64.385520]        worker_thread+0x30/0x570
> [   64.389681]        kthread+0x134/0x164
> [   64.393405]        ret_from_fork+0x14/0x20
> [   64.397477]          (null)
> [   64.400249]
> [   64.400249] -> #0 (prepare_lock){+.+.}:
> [   64.405539]        __mutex_lock+0x7c/0xa98
> [   64.409610]        mutex_lock_nested+0x1c/0x24
> [   64.414029]        clk_prepare_lock+0x50/0xf8
> [   64.418362]        clk_core_get_rate+0xc/0x60
> [   64.422695]        i2s_trigger+0x444/0x6c8
> [   64.426768]        soc_pcm_trigger+0x100/0x140
> [   64.431188]        snd_pcm_action_single+0x38/0x80
> [   64.435953]        snd_pcm_action+0x54/0x5c
> [   64.440112]        snd_pcm_action_lock_irq+0x28/0x3c
> [   64.445052]        snd_pcm_ioctl+0x920/0x123c
> [   64.449386]        do_vfs_ioctl+0xb0/0x9f8
> [   64.453457]        ksys_ioctl+0x34/0x5c
> [   64.457269]        ret_fast_syscall+0x0/0x28
> [   64.461516]        0xbe8db8ec

Thanks,
Charles