On 2022-07-11 4:12 PM, Takashi Iwai wrote:
On Mon, 11 Jul 2022 10:25:17 +0200,
Cezary Rojewski wrote:
...
avs-driver i.e. the bus driver takes responsibility for the codec
device only. There is no real probe(), just the device creation and
initialization of its fields. The rest is handled by the component
driver (sound/soc/hda.c). If this field is cleared and the test is
limited to reloading HDAudio codec module alone, we get a
panic. Something similar to the stack found below my message.
In regard to the other question - are presets freed at all? It seems
all of them are part of the static device-driver matching list. If so,
the pointer is always valid.
When the codec driver is unbound and the module is unloaded, the whole
objects and symbols are gone.
hda_codec_driver_remove() won't get even called when soc-card is being
unbound so everything is still here.
[ 136.827856] RIP: 0010:hda_codec_probe+0x16c/0x560 [snd_soc_hda_codec]
[ 136.828568] Call Trace:
[ 136.828593] <TASK>
[ 136.828628] snd_soc_component_probe+0x3a/0x60 [snd_soc_core]
[ 136.828981] soc_probe_component+0x276/0x4a0 [snd_soc_core]
[ 136.829274] snd_soc_bind_card+0x819/0x13d0 [snd_soc_core]
[ 136.829560] ? __kasan_slab_alloc+0x32/0x90
[ 136.829614] snd_soc_register_card+0x24e/0x260 [snd_soc_core]
[ 136.829900] devm_snd_soc_register_card+0x48/0x90 [snd_soc_core]
[ 136.830204] avs_hdaudio_probe+0x298/0x2c0 [snd_soc_avs_hdaudio]
(...)
Hmm, in the Oops above, at which moment,
snd_hda_codec_cleanup_for_unbind() is called via which function?
Is it the unload of HD-audio codec driver during the probe of AVS
HD-audio?
The preset is assigned to the given HD-audio device object for the
attached codec driver. Once after the codec driver gets unbound, you
must not access to this codec driver's methods any longer, hence we
clear the preset field.
So I wonder how the access to the codec->preset happens after the
codec unbind.
Test scenario:
- enumerate avs-driver stack on machine with HDAudio codec present
- rmmod snd_soc_avs_hdaudio // just the machine board driver i.e.
soc-card driver
- modprobe snd_soc_avs_hdaudio
>>> panic <<<
snd_hda_codec_cleanup_for_unbind() is called in more places than just
HDAudio codec driver's probe() and remove(). It's also called whenever
HDAudio codec soc-component is being removed. Relevant part of the stack
showing when does the cleanup function get called during rmmod:
[ 220.549349] snd_hda_codec_cleanup_for_unbind+0x25/0x451 [snd_hda_codec]
[ 220.549536] ? dump_stack_lvl+0x45/0x49
[ 220.549568] hda_codec_remove.cold+0x14/0x138 [snd_soc_hda_codec]
[ 220.549609] snd_soc_component_remove+0x34/0x40 [snd_soc_core]
[ 220.549942] soc_remove_component+0x113/0x120 [snd_soc_core]
[ 220.550249] soc_cleanup_card_resources+0x1a7/0x4a0 [snd_soc_core]
[ 220.550561] snd_soc_unbind_card+0x9e/0x190 [snd_soc_core]
[ 220.550885] snd_soc_unregister_card+0x28/0x80 [snd_soc_core]
[ 220.551193] devm_card_release+0x1d/0x20 [snd_soc_core]
[ 220.551527] release_nodes+0x73/0x170
[ 220.551549] ? preempt_count_sub+0x18/0xc0
[ 220.551576] devres_release_all+0x10a/0x150
[ 220.551600] ? devres_remove_group+0x260/0x260
[ 220.551630] device_unbind_cleanup+0x14/0xd0
[ 220.551656] device_release_driver_internal+0x146/0x1d0
[ 220.551688] driver_detach+0x81/0xf0
[ 220.551716] bus_remove_driver+0xae/0x170
[ 220.551743] driver_unregister+0x4d/0x70
[ 220.551770] platform_driver_unregister+0x12/0x20
[ 220.551799] avs_hdaudio_driver_exit+0x10/0x12 [snd_soc_avs_hdaudio]
Regards,
Czarek
