Re: [PATCH for-4.11] ASoC: don't dereference NULL pcm_{new,free}

From: Brian Norris <briannorris@chromium.org>
To: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	linux-kernel@vger.kernel.org, Jaroslav Kysela <perex@perex.cz>,
	Takashi Iwai <tiwai@suse.com>,
	alsa-devel@alsa-project.org
Subject: Re: [PATCH for-4.11] ASoC: don't dereference NULL pcm_{new,free}
Date: Fri, 10 Mar 2017 16:39:39 -0800	[thread overview]
Message-ID: <20170311003939.GB4586@google.com> (raw)
In-Reply-To: <87varjz31k.wl%kuninori.morimoto.gx@renesas.com>

Hi Kuninori,

On Thu, Mar 09, 2017 at 12:53:50AM +0000, Kuninori Morimoto wrote:
> > All I know is that I'm definitely hitting a NULL
> > platform->driver->pcm_new callback, and that either reverting your patch
> > or applying the patch I just sent fixes it.
> 
> I want to know why this happen.
> Can you show me which driver is calling snd_soc_add_platform() in your case ?

There are 4 drivers calling that:

  snd_soc_dummy_probe
  rt5514_spi_probe
  2 instances of snd_dmaengine_pcm_register, via rockchip_i2s_probe

Only the latter two seem to run the assignment here:

	if (platform_drv->pcm_new)
		platform->component.pcm_new = snd_soc_platform_drv_pcm_new;

Both snd_soc_dummy_probe and rt5514_spi_probe find ->pcm_new NULL here.

I'm running with the sound/soc/rockchip/rk3399_gru_sound.c platform
driver. If it helps, I'm using the DT posted at [1]. IIUC, the "RT5514
DSP" link is trying to link up a "snd-soc-dummy" instance.

I'm fairly thoroughly confused. Any better ideas?

Brian

[1] https://www.spinics.net/lists/arm-kernel/msg561964.html
    [PATCH v2 4/6] arm64: dts: rockchip: add Gru/Kevin DTS