From: bluhm <bluhm@openbsd.org>
Date: Mon, 22 Aug 2022 21:02:44 +0000 (+0000)
Subject: Document that igmp_timers_are_running and mld6_timers_are_running
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=679bdce925df26b69c4f44c8038c19b7ea755af0;p=openbsd

Document that igmp_timers_are_running and mld6_timers_are_running
are protected by netlock.  They are only used as shortcut in fast
timer.
Common prefix in mld6.c is mld6.
OK mvs@
---

diff --git a/sys/netinet/igmp.c b/sys/netinet/igmp.c
index 251ad71894e..9e01ea88870 100644
--- a/sys/netinet/igmp.c
+++ b/sys/netinet/igmp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: igmp.c,v 1.79 2022/08/21 23:04:45 bluhm Exp $	*/
+/*	$OpenBSD: igmp.c,v 1.80 2022/08/22 21:02:44 bluhm Exp $	*/
 /*	$NetBSD: igmp.c,v 1.15 1996/02/13 23:41:25 christos Exp $	*/
 
 /*
@@ -96,7 +96,7 @@
 
 #define IP_MULTICASTOPTS	0
 
-int		igmp_timers_are_running;
+int	igmp_timers_are_running;	/* [N] shortcut for fast timer */
 static LIST_HEAD(, router_info) rti_head;
 static struct mbuf *router_alert;
 struct cpumem *igmpcounters;
@@ -529,8 +529,9 @@ igmp_fasttimo(void)
 	/*
 	 * 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.
+	 * Variable igmp_timers_are_running is read atomically, but without
+	 * lock intensionally.  In case it is not set due to MP races, we may
+	 * miss to check the timers.  Then run the loop at next fast timeout.
 	 */
 	if (!igmp_timers_are_running)
 		return;
diff --git a/sys/netinet6/mld6.c b/sys/netinet6/mld6.c
index 31c0256b7aa..a58009650f7 100644
--- a/sys/netinet6/mld6.c
+++ b/sys/netinet6/mld6.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mld6.c,v 1.57 2022/08/21 23:04:45 bluhm Exp $	*/
+/*	$OpenBSD: mld6.c,v 1.58 2022/08/22 21:02:44 bluhm Exp $	*/
 /*	$KAME: mld6.c,v 1.26 2001/02/16 14:50:35 itojun Exp $	*/
 
 /*
@@ -84,7 +84,7 @@
 #include <netinet6/mld6_var.h>
 
 static struct ip6_pktopts ip6_opts;
-static int mld_timers_are_running;
+int	mld6_timers_are_running;	/* [N] shortcut for fast timer */
 /* XXX: These are necessary for KAME's link-local hack */
 static struct in6_addr mld_all_nodes_linklocal = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
 static struct in6_addr mld_all_routers_linklocal = IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;
@@ -99,7 +99,7 @@ mld6_init(void)
 	struct ip6_hbh *hbh = (struct ip6_hbh *)hbh_buf;
 	u_int16_t rtalert_code = htons((u_int16_t)IP6OPT_RTALERT_MLD);
 
-	mld_timers_are_running = 0;
+	mld6_timers_are_running = 0;
 
 	/* ip6h_nxt will be fill in later */
 	hbh->ip6h_len = 0;	/* (8 >> 3) - 1 */
@@ -136,7 +136,7 @@ mld6_start_listening(struct in6_multi *in6m)
 		    MLD_RANDOM_DELAY(MLD_V1_MAX_RI *
 		    PR_FASTHZ);
 		in6m->in6m_state = MLD_IREPORTEDLAST;
-		mld_timers_are_running = 1;
+		mld6_timers_are_running = 1;
 	}
 }
 
@@ -266,7 +266,7 @@ mld6_input(struct mbuf *m, int off)
 					in6m->in6m_timer > timer) {
 					in6m->in6m_timer =
 					    MLD_RANDOM_DELAY(timer);
-					mld_timers_are_running = 1;
+					mld6_timers_are_running = 1;
 				}
 			}
 		}
@@ -330,15 +330,16 @@ mld6_fasttimeo(void)
 	/*
 	 * 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.
+	 * Variable mld6_timers_are_running is read atomically, but without
+	 * lock intensionally.  In case it is not set due to MP races, we may
+	 * miss to check the timers.  Then run the loop at next fast timeout.
 	 */
-	if (!mld_timers_are_running)
+	if (!mld6_timers_are_running)
 		return;
 
 	NET_LOCK();
 
-	mld_timers_are_running = 0;
+	mld6_timers_are_running = 0;
 	TAILQ_FOREACH(ifp, &ifnet, if_list)
 		mld6_checktimer(ifp);
 
@@ -363,7 +364,7 @@ mld6_checktimer(struct ifnet *ifp)
 			mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
 			in6m->in6m_state = MLD_IREPORTEDLAST;
 		} else {
-			mld_timers_are_running = 1;
+			mld6_timers_are_running = 1;
 		}
 	}
 }