Reproducible deadlock w. alsa/maestro3 when sleeping (ACPI,) 2.6.0-test1

From: P. Christeas (p_christ@hol.gr)
Date: Mon Jul 14 2003 - 11:17:22 EST


I have been experiencing some fully reproducible deadlock when waking from
sleep, using artsd over ALSA.
The scenario is:
I use ALSA, with the maestro3 device and everything else compiled as modules.
>From userspace, I launch artsd, which uses its native ALSA support to connect
to /dev/pcmXXXXX .
I only have a custom script, which sleeps the machine by a 'echo 1>
/proc/acpi/sleep' . It does NOT stop alsa .
When the machine weaks, it has a deadlock. The suspended 'artsd' process waits
for the /dev/pcmXXXX to become available (presumably; I can see 'D' on the
'ps' line), while the maestro3 module waits for the 'artsd' process to free
/dev/pcmXXX .
I have tried to kill (w. 15, 9 etc.) the artsd process, rmmod the
'snd_maestro3' module (w. '-f' or '-l' options to rmmod). Nothing would
happen. In the worst case (after the rmmod), the whole module mechanism would
lock as well ('lsmod' would hang ).
I could not find any relevant message for this case. However, on a subsequent
sleep, the system refuses to sleep because it cannot suspend 'artsd'.

ps. My scripts (including module-init-tools) are definitely messy. However,
since 'artsd' or any ALSA client works in userspace and can be launched at
any time, I believe this problem leads to serious trouble for the system.

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