[PATCH] ASoC: da7219: Fix general protection fault in da7219_register_dai_clks

[Zhi, Yong]

Hi, Adam,

> -----Original Message-----
> From: Adam Thomson <Adam.Thomson.Opensource at diasemi.com>
> Sent: Thursday, July 30, 2020 10:54 AM
> To: Zhi, Yong <yong.zhi at intel.com>; alsa-devel at alsa-project.org;
> broonie at kernel.org
> Cc: pierre-louis.bossart at linux.intel.com; Adam Thomson
> <Adam.Thomson.Opensource at diasemi.com>
> Subject: RE: [PATCH] ASoC: da7219: Fix general protection fault in
> da7219_register_dai_clks
> 
> On 30 July 2020 15:04, Yong Zhi wrote:
> 
> > clkdev_drop(cl) does not null the removed cl, if
> > da7219_register_dai_clks() entered again after card removal,
> > devm_clk_register() will return -EEXIST, the goto err to clkdev_drop() will
> trigger board reboot.
> >
> > Test commands:
> >    modprobe -r snd_sof_pci
> >    modprobe snd_sof_pci
> >
> > The oops looks like:
> >
> > da7219 i2c-DLGS7219:00: Using default DAI clk names: da7219-dai-wclk,
> > da7219- dai-bclk
> > da7219 i2c-DLGS7219:00: Failed to register da7219-dai-wclk: -17
> > general protection fault: 0000 [#1] PREEMPT SMP NOPTI
> > RIP: 0010:clkdev_drop+0x20/0x52
> > Call Trace:
> >  da7219_probe+0x52e/0x6dc [snd_soc_da7219]
> >  soc_probe_component+0x206/0x3a1
> >  snd_soc_bind_card+0x4ee/0x9a6
> >  devm_snd_soc_register_card+0x48/0x7b
> >  audio_probe+0x1f0/0x221 [snd_soc_sof_da7219_max98373]
> >  platform_drv_probe+0x89/0xa2
> >  really_probe+0x129/0x30d
> >  driver_probe_device+0x59/0xec
> >  ? driver_sysfs_remove+0x55/0x55
> >  bus_for_each_drv+0xa1/0xdc
> >  __device_attach+0xc2/0x146
> >  bus_probe_device+0x32/0x97
> >  device_add+0x311/0x3b4
> >  platform_device_add+0x184/0x1eb
> >
> > Fix by marking (nullifying) the da7219->dai_clks_lookup[i] after
> > clkdev_drop().
> >
> > Signed-off-by: Yong Zhi <yong.zhi at intel.com>
> > ---
> >  sound/soc/codecs/da7219.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
> > index 153ea30b5a8f..54da7cfbb5f4 100644
> > --- a/sound/soc/codecs/da7219.c
> > +++ b/sound/soc/codecs/da7219.c
> > @@ -2369,8 +2369,10 @@ static void da7219_remove(struct
> > snd_soc_component *component)
> >
> >  #ifdef CONFIG_COMMON_CLK
> >  	for (i = DA7219_DAI_NUM_CLKS - 1; i >= 0; --i) {
> > -		if (da7219->dai_clks_lookup[i])
> > +		if (da7219->dai_clks_lookup[i]) {
> >  			clkdev_drop(da7219->dai_clks_lookup[i]);
> > +			da7219->dai_clks_lookup[i] = NULL;
> > +		}
> 
> It seems to me that devm_* functions should have freed up everything when the
> codec module was removed. I can only assume the codec isn't being removed in
> your test hence devm is never freeing the clock resource and is why you're
> getting -EEXIST. Is this the case and is your use-case expected behaviour? It's
> not something that has been reported previously so am keen to understand
> exactly what's happening here.
> 
> >  	}
> >  #endif
> >

When the card was uninstalled with modprobe -r, the da7219 codec was not removed, only component da7219_remove() is invoked, do you suggest the component driver probe and remove has to happen with da7219_i2_driver probe and remove together? Thanks for the code review.  

> > --
> > 2.7.4