Commit c647f806b8 ("ALSA: hda - Allow multiple ADCs for mic mute LED
controls") changed the return value of the snd_hda_gen_add_micmute_led()
without actually updating the callers.
Admittedly, almost no callers actually cared about the return value.
But one call site very much did: the Dell wmi code. It would see the
registration return zero, which _used_ to mean "failed" but now means
"success", and clear the dell_micmute_led_set_func pointer.
End result: the successful registration would end up calling the Dell
code that thought it had all failed, and call through a NULL pointer.
To make matters worse, it ends up being a tail-call, and with the
retpoline sequence you don't even see the caller (dell_micmute_update())
in the stack trace, so the error ended up way less obvious than it
should have been.
Fixes: c647f806b8 "ALSA: hda - Allow multiple ADCs for mic mute LED controls"
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
70b20dd7f8