On 1/17/23 09:47, Cezary Rojewski wrote: > Several functions that take part in codec's initialization and removal > are re-used by ASoC codec drivers implementations. Drivers mimic the > behavior of hda_codec_driver_probe/remove() found in > sound/pci/hda/hda_bind.c with their component->probe/remove() instead. > > One of the reasons for that is the expectation of > snd_hda_codec_device_new() to receive a valid struct snd_card pointer > what cannot be fulfilled on ASoC side until a card is attempted to be very hard to follow. Is there a spurious 'what' to be removed? Or is there missing text? Please consider rewording with simpler sentences. > bound and its component probing is triggered. > > As ASoC sound card may be unbound without codec device being actually > removed from the system, unsetting ->preset in > snd_hda_codec_cleanup_for_unbind() interferes with module unload -> load > scenario causing null-ptr-deref. Preset is assigned only once, during > device/driver matching whereas ASoC codec driver's module reloading may > occur several times throughout the lifetime of an audio stack. > > Signed-off-by: Cezary Rojewski <cezary.rojewski@xxxxxxxxx> > --- > > This is a continuation of a discussion that begun in the middle of 2022 > [1] and was part of a larger series addressing several HDAudio topics. > > Single rmmod on ASoC's codec driver module is enough to cause a panic. > Given our results, no regression shows up with modprobe/rmmod on > snd_hda_intel side with this patch applied. > > [1]: https://lore.kernel.org/alsa-devel/20220706120230.427296-2-cezary.rojewski@xxxxxxxxx/ > > sound/pci/hda/hda_codec.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c > index edd653ece70d..ac1cc7c5290e 100644 > --- a/sound/pci/hda/hda_codec.c > +++ b/sound/pci/hda/hda_codec.c > @@ -795,7 +795,6 @@ void snd_hda_codec_cleanup_for_unbind(struct hda_codec *codec) > snd_array_free(&codec->cvt_setups); > snd_array_free(&codec->spdif_out); > snd_array_free(&codec->verbs); > - codec->preset = NULL; > codec->follower_dig_outs = NULL; > codec->spdif_status_reset = 0; > snd_array_free(&codec->mixers);
