Re: [alsa-devel] sound: uninterruptible hang in snd_seq_oss_writeq_sync

On Tue, 01 Mar 2016 13:33:27 +0100, Dmitry Vyukov wrote:

Hello,

The following program creates an unkillable process:

.....

The hang stack is:

[<ffffffff85309f77>] snd_seq_oss_writeq_sync+0x327/0x790 sound/core/seq/oss/seq_oss_writeq.c:121

This is wait_event_interruptible_timeout(q->sync_sleep, ! q->sync_event_put, HZ);

and this should return zero if (signal_pending(current)) /* interrupted - return 0 to finish sync */ q->sync_event_put = 0; if (! q->sync_event_put || q->sync_time >= time) return 0; return 1;

[<ffffffff852fa353>] snd_seq_oss_drain_write+0x113/0x160

... and this loop should break: while (snd_seq_oss_writeq_sync(dp->writeq)) ;

So, I see no obvious error in the code, so far.

I'm running your test program now with 8 parallel runs, but I couldn't reproduce it. Any other specifics?

thanks,

Takashi