Re: Multicast routing stops functioning after 4G multicast packets recived.

[Hannes Frederic Sowa <hannes@stressinduktion.org>]

On Tue, Jan 07, 2014 at 09:11:47PM +0100, Hannes Frederic Sowa wrote:
> On Tue, Jan 07, 2014 at 06:43:22PM +0100, Hannes Frederic Sowa wrote:
> > On Tue, Jan 07, 2014 at 06:01:44PM +0100, Bob Falken wrote:
> > > Hello,
> > > 
> > > I patched, kernel 3.2.53 yesterday,
> > > 8774002632packets, and ~9.1TB later, the multicast routing seems to function properly. :)
> > > 
> > > Kudos for fixing this.
> > > 
> > > I will keep checking the next days.
> > > 
> > > As for IPv6 MR, my current setup i.e: the Multicast source, does not support IPv6, so cannot do a check for that natively.
> > > 
> > > Unless I can translate IPv4 multicast into IPv6 multicast easily, using some iptable prerouting rules(?).
> > 
> > Thank you for testing!
> > 
> > I'll review the RCU regions again and will prepare the patches (before
> > introduction of ebc0ffae5dfb44 ("fib: RCU conversion of fib_lookup()")
> > and after.
> 
> It seems ip(6)mr_fib_lookup is not always called  from rcu section
> (ndo_start_xmit), so I had to restructure a bit. Could you retest this
> patch as preparation for a submission to stable? Thanks!
> 
> RCU conversion can be done later then.

Broken patch, sorry. Please try this one:

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 421a249..e5e9071 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -157,9 +157,12 @@ static struct mr_table *ipmr_get_table(struct net *net, u32 id)
 static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4,
 			   struct mr_table **mrt)
 {
-	struct ipmr_result res;
-	struct fib_lookup_arg arg = { .result = &res, };
 	int err;
+	struct ipmr_result res;
+	struct fib_lookup_arg arg = {
+		.result = &res,
+		.flags = FIB_LOOKUP_NOREF,
+	};
 
 	err = fib_rules_lookup(net->ipv4.mr_rules_ops,
 			       flowi4_to_flowi(flp4), 0, &arg);
@@ -448,16 +451,22 @@ failure:
 
 static netdev_tx_t reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
 {
+	int err;
+	struct ipmr_result res;
 	struct net *net = dev_net(dev);
-	struct mr_table *mrt;
+
+	struct fib_lookup_arg arg = {
+		.result = &res,
+	};
+
 	struct flowi4 fl4 = {
 		.flowi4_oif	= dev->ifindex,
 		.flowi4_iif	= skb->skb_iif,
 		.flowi4_mark	= skb->mark,
 	};
-	int err;
 
-	err = ipmr_fib_lookup(net, &fl4, &mrt);
+	err = fib_rules_lookup(net->ipv4.mr_rules_ops,
+			       flowi4_to_flowi(&fl4), 0, &arg);
 	if (err < 0) {
 		kfree_skb(skb);
 		return err;
@@ -466,9 +475,12 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
 	read_lock(&mrt_lock);
 	dev->stats.tx_bytes += skb->len;
 	dev->stats.tx_packets++;
-	ipmr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, IGMPMSG_WHOLEPKT);
+	ipmr_cache_report(res.mrt, skb, res.mrt->mroute_reg_vif_num,
+			  IGMPMSG_WHOLEPKT);
 	read_unlock(&mrt_lock);
 	kfree_skb(skb);
+	if (arg.rule)
+		fib_rule_put(arg.rule);
 	return NETDEV_TX_OK;
 }
 
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index f365310..45ec621 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -141,9 +141,12 @@ static struct mr6_table *ip6mr_get_table(struct net *net, u32 id)
 static int ip6mr_fib_lookup(struct net *net, struct flowi6 *flp6,
 			    struct mr6_table **mrt)
 {
-	struct ip6mr_result res;
-	struct fib_lookup_arg arg = { .result = &res, };
 	int err;
+	struct ip6mr_result res;
+	struct fib_lookup_arg arg = {
+		.result = &res,
+		.flags = FIB_LOOKUP_NOREF,
+	};
 
 	err = fib_rules_lookup(net->ipv6.mr6_rules_ops,
 			       flowi6_to_flowi(flp6), 0, &arg);
@@ -693,16 +696,20 @@ static const struct inet6_protocol pim6_protocol = {
 static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
 				      struct net_device *dev)
 {
+	int err;
+	struct ip6mr_result res;
 	struct net *net = dev_net(dev);
-	struct mr6_table *mrt;
 	struct flowi6 fl6 = {
 		.flowi6_oif	= dev->ifindex,
 		.flowi6_iif	= skb->skb_iif,
 		.flowi6_mark	= skb->mark,
 	};
-	int err;
+	struct fib_lookup_arg arg = {
+		.result = &res,
+	};
 
-	err = ip6mr_fib_lookup(net, &fl6, &mrt);
+	err = fib_rules_lookup(net->ipv6.mr6_rules_ops,
+			flowi6_to_flowi(&fl6), 0, &arg);
 	if (err < 0) {
 		kfree_skb(skb);
 		return err;
@@ -711,9 +718,12 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
 	read_lock(&mrt_lock);
 	dev->stats.tx_bytes += skb->len;
 	dev->stats.tx_packets++;
-	ip6mr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, MRT6MSG_WHOLEPKT);
+	ip6mr_cache_report(res.mrt, skb, res.mrt->mroute_reg_vif_num,
+			   MRT6MSG_WHOLEPKT);
 	read_unlock(&mrt_lock);
 	kfree_skb(skb);
+	if (arg.rule)
+		fib_rule_put(arg.rule);
 	return NETDEV_TX_OK;
 }