Only grab netlock in igmp and mdl6 fast timer when necessary. There

are status variables that can be used to avoid locking if timers
are not running.  This should reduce contention on exclusive netlock.
OK kn@ mvs@

diff --git a/sys/netinet/igmp.c b/sys/netinet/igmp.c
index 9730742..251ad71 100644 (file)
--- a/sys/netinet/igmp.c
+++ b/sys/netinet/igmp.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: igmp.c,v 1.78 2022/03/28 16:31:26 bluhm Exp $ */
+/*     $OpenBSD: igmp.c,v 1.79 2022/08/21 23:04:45 bluhm Exp $ */
 /*     $NetBSD: igmp.c,v 1.15 1996/02/13 23:41:25 christos Exp $       */
 
 /*
@@ -526,24 +526,24 @@ igmp_fasttimo(void)
 {
        struct ifnet *ifp;
 
-       NET_LOCK();
-
        /*
         * Quick check to see if any work needs to be done, in order
         * to minimize the overhead of fasttimo processing.
+        * Variable igmp_timers_are_running is read atomically.  In case we
+        * miss a fast timer due to MP races, just run it next time.
         */
        if (!igmp_timers_are_running)
-               goto out;
+               return;
+
+       NET_LOCK();
 
        igmp_timers_are_running = 0;
        TAILQ_FOREACH(ifp, &ifnet, if_list)
                igmp_checktimer(ifp);
 
-out:
        NET_UNLOCK();
 }
 
-
 void
 igmp_checktimer(struct ifnet *ifp)
 {

diff --git a/sys/netinet6/mld6.c b/sys/netinet6/mld6.c
index 2e38629..31c0256 100644 (file)
--- a/sys/netinet6/mld6.c
+++ b/sys/netinet6/mld6.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mld6.c,v 1.56 2018/11/30 09:28:34 claudio Exp $       */
+/*     $OpenBSD: mld6.c,v 1.57 2022/08/21 23:04:45 bluhm Exp $ */
 /*     $KAME: mld6.c,v 1.26 2001/02/16 14:50:35 itojun Exp $   */
 
 /*
@@ -327,20 +327,21 @@ mld6_fasttimeo(void)
 {
        struct ifnet *ifp;
 
-       NET_LOCK();
-
        /*
         * Quick check to see if any work needs to be done, in order
         * to minimize the overhead of fasttimo processing.
+        * Variable mld_timers_are_running is read atomically.  In case we
+        * miss a fast timer due to MP races, just run it next time.
         */
        if (!mld_timers_are_running)
-               goto out;
+               return;
+
+       NET_LOCK();
 
        mld_timers_are_running = 0;
        TAILQ_FOREACH(ifp, &ifnet, if_list)
                mld6_checktimer(ifp);
 
-out:
        NET_UNLOCK();
 }