Two changes:

Currently carp_send_ad is called under splsoftclock, but this may
be unsafe due to calls into pf_test via ip_output.  Raise the
priority level to splsoftnet for the function run.  It might be
possible to get away with the splsoftnet just over the ip_output
call.

Also, in the case where the mbuf tagging fails due to out of memory
in carp_prepare_ad, we would stop sending advertisements.  Treat
this as per the other out of memory case, which retries at the next
scheduled interval.

Diff against OPENBSD_3_6.

Chris Pascoe
2004/10/05

Index: netinet/ip_carp.c
===================================================================
RCS file: /cvs/src/sys/netinet/ip_carp.c,v
retrieving revision 1.62
diff -u -r1.62 ip_carp.c
--- netinet/ip_carp.c	31 Aug 2004 05:31:39 -0000	1.62
+++ netinet/ip_carp.c	5 Oct 2004 02:25:06 -0000
@@ -793,7 +793,9 @@
 	struct carp_softc *sc = v;
 	struct carp_header *ch_ptr;
 	struct mbuf *m;
-	int len, advbase, advskew;
+	int len, advbase, advskew, s;
+
+	s = splsoftnet();
 
 	/* bow out if we've lost our UPness or RUNNINGuiness */
 	if ((sc->sc_ac.ac_if.if_flags &
@@ -829,9 +831,7 @@
 			sc->sc_ac.ac_if.if_oerrors++;
 			carpstats.carps_onomem++;
 			/* XXX maybe less ? */
-			if (advbase != 255 || advskew != 255)
-				timeout_add(&sc->sc_ad_tmo, tvtohz(&tv));
-			return;
+			goto retry_later;
 		}
 		len = sizeof(*ip) + sizeof(ch);
 		m->m_pkthdr.len = len;
@@ -855,7 +855,7 @@
 		ch_ptr = (void *)ip + sizeof(*ip);
 		bcopy(&ch, ch_ptr, sizeof(ch));
 		if (carp_prepare_ad(m, sc, ch_ptr))
-			return;
+			goto retry_later;
 
 		m->m_data += sizeof(*ip);
 		ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip));
@@ -897,9 +897,7 @@
 			sc->sc_ac.ac_if.if_oerrors++;
 			carpstats.carps_onomem++;
 			/* XXX maybe less ? */
-			if (advbase != 255 || advskew != 255)
-				timeout_add(&sc->sc_ad_tmo, tvtohz(&tv));
-			return;
+			goto retry_later;
 		}
 		len = sizeof(*ip6) + sizeof(ch);
 		m->m_pkthdr.len = len;
@@ -923,7 +921,7 @@
 		ch_ptr = (void *)ip6 + sizeof(*ip6);
 		bcopy(&ch, ch_ptr, sizeof(ch));
 		if (carp_prepare_ad(m, sc, ch_ptr))
-			return;
+			goto retry_later;
 
 		m->m_data += sizeof(*ip6);
 		ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip6));
@@ -957,6 +955,8 @@
 	}
 #endif /* INET6 */
 
+retry_later:
+	splx(s);
 	if (advbase != 255 || advskew != 255)
 		timeout_add(&sc->sc_ad_tmo, tvtohz(&tv));
 }