On 2023-01-17 5:01 PM, Takashi Iwai wrote:
...
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.
I think one possible regression by this change would be the case you
reload another codec driver. With keeping codec->preset, it's still
thought as if already matched, and a wrong one could be used.
And, this would be nothing but a leak of the possibly freed address.
After hda_codec_driver_remove(), card->preset may point to an already
freed address.
So, just removing isn't right. It has to be cleared somewhere
instead, e.g. in hda_bind.c.
But, one thing I'm still concerned is that your comment about the call
without the card binding. Do you mean that the
snd_hda_codec_cleanup_for_unbind() may be called even if codec->card
isn't set?
One proposition would be to add line:
codec->preset = NULL;
after both invocations of snd_hda_codec_cleanup_for_unbind() in
hda_codec_driver_probe/remove() in sound/pci/hda/hda_bind.c.
In regard to your last question - no, cleanup is only called either in
component->probe()'s error path or in component->remove() once
snd_hda_codec_device_new() succeeds and thus, codec->card points to a
valid sound card.
What I meant by my comment, is that removal of any components of an ASoC
sound card will cause all other components to have their ->remove() op
called too. Let's say I unload snd_soc_avs_hdaudio module without
unloading snd_soc_avs. As bus (snd_soc_avs) owns the codecs, its
platform component->remove() gets called right after codec
component->remove() but the actual devices are still present in the
system even with the sound card module (snd_soc_avs_hdaudio) unloaded.
Regards,
Czarek
