svn commit: r211896 - head/sbin/hastd
Pawel Jakub Dawidek
pjd at FreeBSD.org
Sat Aug 28 08:50:56 UTC 2010
On Sat, Aug 28, 2010 at 11:43:55AM +0300, Kostik Belousov wrote:
> On Fri, Aug 27, 2010 at 11:54:02PM +0200, Pawel Jakub Dawidek wrote:
> > On Sat, Aug 28, 2010 at 12:38:27AM +0300, Kostik Belousov wrote:
> > > > --- head/sbin/hastd/primary.c Fri Aug 27 20:48:12 2010 (r211895)
> > > > +++ head/sbin/hastd/primary.c Fri Aug 27 20:49:06 2010 (r211896)
> > > > @@ -1988,7 +1988,9 @@ guard_thread(void *arg)
> > > > rw_unlock(&hio_remote_lock[ii]);
> > > > }
> > > > }
> > > > - (void)cv_timedwait(&hio_guard_cond, &hio_guard_lock, timeout);
> > > > + /* Sleep only if a signal wasn't delivered in the meantime. */
> > > > + if (!sigexit_received && !sighup_received && !sigchld_received)
> > > > + cv_timedwait(&hio_guard_cond, &hio_guard_lock, timeout);
> > > > mtx_unlock(&hio_guard_lock);
> > > > }
> > > > /* NOTREACHED */
> > > I wanted to say that this is racy, because if a signal is delivered after
> > > the check is done but before the sleep, you loose.
> > Yes, I know it is racy, but the race isn't critical anymore, as we will
> > eventually wait at most 10 seconds to handle signals.
> > > After looking at the signal handler, I noted that you call not async-safe
> > > functions in the handler. This is easy way to get undefined behaviour,
> > > i.e. probably crash. And wakeup from the handler would have the same
> > > race as sigXXX_received check.
> > Which aren't async-safe? pthread stuff?
> Yes. All pthread_* namespace is not async-signal safe.
Ehh, I'm lame. All I need to do is to use cv_timedwait_sig() instead of
cv_timedwait() and I can remove all pthread stuff from the sighandler.
Pawel Jakub Dawidek http://www.wheelsystems.com
pjd at FreeBSD.org http://www.FreeBSD.org
FreeBSD committer Am I Evil? Yes, I Am!
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