Date: Sat, 28 Aug 2010 10:50:42 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r211896 - head/sbin/hastd Message-ID: <20100828085042.GE2077@garage.freebsd.pl> In-Reply-To: <20100828084355.GH2396@deviant.kiev.zoral.com.ua> References: <201008272049.o7RKn63o007138@svn.freebsd.org> <20100827213827.GD2396@deviant.kiev.zoral.com.ua> <20100827215402.GB2077@garage.freebsd.pl> <20100828084355.GH2396@deviant.kiev.zoral.com.ua>
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[-- Attachment #1 --] 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. Thanks! -- Pawel Jakub Dawidek http://www.wheelsystems.com pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAkx4zeEACgkQForvXbEpPzQzVwCg6vf4JuovOKYGcXPIkBI+M8fK 6egAoJbBt5qDJAxFcTbQozb+dQUVfFK/ =EJHx -----END PGP SIGNATURE-----help
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