igmp: do not remove igmp souce list info when set link down

commit 24803f38 upstream.

In commit 24cf3af3 ("igmp: call ip_mc_clear_src..."), we forgot to remove
igmpv3_clear_delrec() in ip_mc_down(), which also called ip_mc_clear_src().
This make us clear all IGMPv3 source filter info after NETDEV_DOWN.
Move igmpv3_clear_delrec() to ip_mc_destroy_dev() and then no need
ip_mc_clear_src() in ip_mc_destroy_dev().

On the other hand, we should restore back instead of free all source filter
info in igmpv3_del_delrec(). Or we will not able to restore IGMPv3 source
filter info after NETDEV_UP and NETDEV_POST_TYPE_CHANGE.

Fixes: 24cf3af3 ("igmp: call ip_mc_clear_src() only when ...")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - Use IGMP_Unsolicited_Report_Count instead of sysctl_igmp_qrv
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/ipv4/igmp.c

@@ -140,7 +140,7 @@
 	  time_before(jiffies, (in_dev)->mr_v2_seen)))
 
 static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im);
-static void igmpv3_del_delrec(struct in_device *in_dev, __be32 multiaddr);
+static void igmpv3_del_delrec(struct in_device *in_dev, struct ip_mc_list *im);
 static void igmpv3_clear_delrec(struct in_device *in_dev);
 static int sf_setstate(struct ip_mc_list *pmc);
 static void sf_markstate(struct ip_mc_list *pmc);
@@ -1082,10 +1082,14 @@ static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im)
 	spin_unlock_bh(&in_dev->mc_tomb_lock);
 }
 
-static void igmpv3_del_delrec(struct in_device *in_dev, __be32 multiaddr)
+/*
+ * restore ip_mc_list deleted records
+ */
+static void igmpv3_del_delrec(struct in_device *in_dev, struct ip_mc_list *im)
 {
 	struct ip_mc_list *pmc, *pmc_prev;
-	struct ip_sf_list *psf, *psf_next;
+	struct ip_sf_list *psf;
+	__be32 multiaddr = im->multiaddr;
 
 	spin_lock_bh(&in_dev->mc_tomb_lock);
 	pmc_prev = NULL;
@@ -1101,16 +1105,26 @@ static void igmpv3_del_delrec(struct in_device *in_dev, __be32 multiaddr)
 			in_dev->mc_tomb = pmc->next;
 	}
 	spin_unlock_bh(&in_dev->mc_tomb_lock);
+
+	spin_lock_bh(&im->lock);
 	if (pmc) {
-		for (psf=pmc->tomb; psf; psf=psf_next) {
-			psf_next = psf->sf_next;
-			kfree(psf);
+		im->interface = pmc->interface;
+		im->crcount = in_dev->mr_qrv ?: IGMP_Unsolicited_Report_Count;
+		im->sfmode = pmc->sfmode;
+		if (pmc->sfmode == MCAST_INCLUDE) {
+			im->tomb = pmc->tomb;
+			im->sources = pmc->sources;
+			for (psf = im->sources; psf; psf = psf->sf_next)
+				psf->sf_crcount = im->crcount;
 		}
 		in_dev_put(pmc->interface);
-		kfree(pmc);
 	}
+	spin_unlock_bh(&im->lock);
 }
 
+/*
+ * flush ip_mc_list deleted records
+ */
 static void igmpv3_clear_delrec(struct in_device *in_dev)
 {
 	struct ip_mc_list *pmc, *nextpmc;
@@ -1255,7 +1269,7 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
 	rcu_assign_pointer(in_dev->mc_list, im);
 
 #ifdef CONFIG_IP_MULTICAST
-	igmpv3_del_delrec(in_dev, im->multiaddr);
+	igmpv3_del_delrec(in_dev, im);
 #endif
 	igmp_group_added(im);
 	if (!in_dev->dead)
@@ -1345,8 +1359,12 @@ void ip_mc_remap(struct in_device *in_dev)
 
 	ASSERT_RTNL();
 
-	for_each_pmc_rtnl(in_dev, pmc)
+	for_each_pmc_rtnl(in_dev, pmc) {
+#ifdef CONFIG_IP_MULTICAST
+		igmpv3_del_delrec(in_dev, pmc);
+#endif
 		igmp_group_added(pmc);
+	}
 }
 
 /* Device going down */
@@ -1367,7 +1385,6 @@ void ip_mc_down(struct in_device *in_dev)
 	in_dev->mr_gq_running = 0;
 	if (del_timer(&in_dev->mr_gq_timer))
 		__in_dev_put(in_dev);
-	igmpv3_clear_delrec(in_dev);
 #endif
 
 	ip_mc_dec_group(in_dev, IGMP_ALL_HOSTS);
@@ -1402,8 +1419,12 @@ void ip_mc_up(struct in_device *in_dev)
 
 	ip_mc_inc_group(in_dev, IGMP_ALL_HOSTS);
 
-	for_each_pmc_rtnl(in_dev, pmc)
+	for_each_pmc_rtnl(in_dev, pmc) {
+#ifdef CONFIG_IP_MULTICAST
+		igmpv3_del_delrec(in_dev, pmc);
+#endif
 		igmp_group_added(pmc);
+	}
 }
 
 /*
@@ -1418,13 +1439,13 @@ void ip_mc_destroy_dev(struct in_device *in_dev)
 
 	/* Deactivate timers */
 	ip_mc_down(in_dev);
+#ifdef CONFIG_IP_MULTICAST
+	igmpv3_clear_delrec(in_dev);
+#endif
 
 	while ((i = rtnl_dereference(in_dev->mc_list)) != NULL) {
 		in_dev->mc_list = i->next_rcu;
 		in_dev->mc_count--;
-
-		/* We've dropped the groups in ip_mc_down already */
-		ip_mc_clear_src(i);
 		ip_ma_put(i);
 	}
 }