Re: [ACPI] S3 and sigwait (was Re: 2.6.13-rc3: swsusp works (TP 600X))

From: Pavel Machek
Date: Sat Jul 30 2005 - 05:32:09 EST


> >> One other glitch is that pdnsd (a nameserver caching daemon) has crashed
> >> when the system wakes up from swsusp. It also happens when waking up
> >> from S3, which was working with although not with 2.6.13-rc3.
> >> Many people have said mysql also does not suspend well. Is their use of
> >> a named pipe or socket causing the problem?
> > No idea, strace?
> The upshot of stracing is in tthe Debian BTS <>
> #319572. Paul Rombouts, an author of pdnsd, reproduced the strace
> crash and found the problem:
> > Apparently strace causes sigwait to return EINTR, which is
> > inconsistent with the documentation I could find on sigwait.
> Which is true. The sigwait man entry (Debian 'etch') says:
> The !sigwait! function never returns an error.
> His patch (available in the BTS and included below) fixed the problem
> of strace or S3 sleep crashing pdnsd.

If you think it is a linux bug, can you produce small test case doing
just the sigwait, and post it on l-k with big title "sigwait() breaks
when straced, and on suspend"?

That way it is going to get some attetion, and you'll get either
documentation or kernel fixed.

teflon -- maybe it is a trademark, but it should not be.
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