Date: Wed, 25 Feb 2009 12:22:25 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org Subject: Re: svn commit: r189029 - stable/7/sys/net Message-ID: <alpine.BSF.2.00.0902251221390.72282@fledge.watson.org> In-Reply-To: <200902251118.n1PBIIcQ094668@svn.freebsd.org> References: <200902251118.n1PBIIcQ094668@svn.freebsd.org>
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On Wed, 25 Feb 2009, Robert Watson wrote: > Author: rwatson > Date: Wed Feb 25 11:18:18 2009 > New Revision: 189029 > URL: http://svn.freebsd.org/changeset/base/189029 > > Log: > Correct a deadlock and a rtentry leak in rt_check(): > > - In the event that a gateway route has to be looked up, drop the lock > on 'rt' before reacquiring it 'rt0' in order to avoid deadlock. > > - In the event the original route has evaporated or is no longer up > after the gateway route lookup, call RTFREE() on the gateway route > before retrying. > > This is a potential errata candidate patch. Just to clarify preemptively: rt_check() isn't present in 8.x due to the link layer routing rewrite, so this was committed directly to 7.x. Robert N M Watson Computer Laboratory University of Cambridge > > PR: kern/130652 > Submitted by: Dmitrij Tejblum <tejblum at yandex-team.ru> > Reviewed by: bz > Tested by: Pete French <petefrench at ticketswitch.com> > > Modified: > stable/7/sys/net/route.c > > Modified: stable/7/sys/net/route.c > ============================================================================== > --- stable/7/sys/net/route.c Wed Feb 25 11:13:13 2009 (r189028) > +++ stable/7/sys/net/route.c Wed Feb 25 11:18:18 2009 (r189029) > @@ -1650,27 +1650,34 @@ retry: > return (ENETUNREACH); > } > /* > - * Relock it and lose the added reference. > - * All sorts of things could have happenned while we > - * had no lock on it, so check for them. > + * Relock it and lose the added reference. All sorts > + * of things could have happenned while we had no > + * lock on it, so check for them. rt need to be > + * unlocked to avoid possible deadlock. > */ > + RT_UNLOCK(rt); > RT_RELOCK(rt0); > - if (rt0 == NULL || ((rt0->rt_flags & RTF_UP) == 0)) > + if (rt0 == NULL || ((rt0->rt_flags & RTF_UP) == 0)) { > /* Ru-roh.. what we had is no longer any good */ > + RTFREE(rt); > goto retry; > + } > /* > * While we were away, someone replaced the gateway. > * Since a reference count is involved we can't just > * overwrite it. > */ > if (rt0->rt_gwroute) { > - if (rt0->rt_gwroute != rt) { > - RTFREE_LOCKED(rt); > - goto retry; > - } > + if (rt0->rt_gwroute != rt) > + RTFREE(rt); > } else { > rt0->rt_gwroute = rt; > } > + /* > + * Since rt was not locked, we need recheck that > + * it still may be used (e.g. up) > + */ > + goto retry; > } > RT_LOCK_ASSERT(rt); > RT_UNLOCK(rt0); >
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