Merge branch 'mlxsw-Improve-IPv6-route-insertion-rate'

Ido Schimmel says:

====================
mlxsw: Improve IPv6 route insertion rate

Unlike IPv4, an IPv6 multipath route in the kernel is composed from
multiple sibling routes, each representing a single nexthop.

Therefore, an addition of a multipath route with N nexthops translates
to N in-kernel notifications. This is inefficient for device drivers
that need to program the route to the underlying device. Each time a new
nexthop is appended, a new nexthop group needs to be constructed and the
old one deleted.

This patchset improves the situation by sending a single notification
for a multipath route addition / deletion instead of one per-nexthop.
When adding thousands of multipath routes with 16 nexthops, I measured
an improvement of about x10 in the insertion rate.

Patches #1-#3 add a flag that indicates that in-kernel notifications
need to be suppressed and extend the IPv6 FIB notification info with
information about the number of sibling routes that are being notified.

Patches #4-#5 adjust the two current listeners to these notifications to
ignore notifications about IPv6 multipath routes.

Patches #6-#7 adds add / delete notifications for IPv6 multipath routes.

Patches #8-#14 do the same for mlxsw.

Patch #15 finally removes the limitations added in patches #4-#5 and
stops the kernel from sending a notification for each added / deleted
nexthop.

Patch #16 adds test cases.

v2 (David Ahern):
* Remove patch adjusting netdevsim to consume resources for each
  fib6_info. Instead, consume one resource for the entire multipath
  route
* Remove 'multipath_rt' usage in patch #10
* Remove 'multipath_rt' from 'struct fib6_entry_notifier_info' in patch
  #15. The member is only removed in this patch to prevent drivers from
  processing multipath routes twice during the series
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip6_fib.h

@@ -377,6 +377,7 @@ typedef struct rt6_info *(*pol_lookup_t)(struct net *,
 struct fib6_entry_notifier_info {
 	struct fib_notifier_info info; /* must be first */
 	struct fib6_info *rt;
+	unsigned int nsiblings;
 };
 
 /*
@@ -450,6 +451,11 @@ int call_fib6_entry_notifiers(struct net *net,
 			      enum fib_event_type event_type,
 			      struct fib6_info *rt,
 			      struct netlink_ext_ack *extack);
+int call_fib6_multipath_entry_notifiers(struct net *net,
+					enum fib_event_type event_type,
+					struct fib6_info *rt,
+					unsigned int nsiblings,
+					struct netlink_ext_ack *extack);
 void fib6_rt_update(struct net *net, struct fib6_info *rt,
 		    struct nl_info *info);
 void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,

include/net/netlink.h

@@ -378,13 +378,17 @@ struct nla_policy {
 /**
  * struct nl_info - netlink source information
  * @nlh: Netlink message header of original request
+ * @nl_net: Network namespace
  * @portid: Netlink PORTID of requesting application
+ * @skip_notify: Skip netlink notifications to user space
+ * @skip_notify_kernel: Skip selected in-kernel notifications
  */
 struct nl_info {
 	struct nlmsghdr		*nlh;
 	struct net		*nl_net;
 	u32			portid;
-	bool			skip_notify;
+	u8			skip_notify:1,
+				skip_notify_kernel:1;
 };
 
 /**

net/ipv6/ip6_fib.c

@@ -381,6 +381,22 @@ int call_fib6_entry_notifiers(struct net *net,
 	return call_fib6_notifiers(net, event_type, &info.info);
 }
 
+int call_fib6_multipath_entry_notifiers(struct net *net,
+					enum fib_event_type event_type,
+					struct fib6_info *rt,
+					unsigned int nsiblings,
+					struct netlink_ext_ack *extack)
+{
+	struct fib6_entry_notifier_info info = {
+		.info.extack = extack,
+		.rt = rt,
+		.nsiblings = nsiblings,
+	};
+
+	rt->fib6_table->fib_seq++;
+	return call_fib6_notifiers(net, event_type, &info.info);
+}
+
 struct fib6_dump_arg {
 	struct net *net;
 	struct notifier_block *nb;
@@ -1123,11 +1139,13 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 add:
 		nlflags |= NLM_F_CREATE;
 
-		err = call_fib6_entry_notifiers(info->nl_net,
-						FIB_EVENT_ENTRY_ADD,
-						rt, extack);
-		if (err)
-			return err;
+		if (!info->skip_notify_kernel) {
+			err = call_fib6_entry_notifiers(info->nl_net,
+							FIB_EVENT_ENTRY_ADD,
+							rt, extack);
+			if (err)
+				return err;
+		}
 
 		rcu_assign_pointer(rt->fib6_next, iter);
 		fib6_info_hold(rt);
@@ -1152,11 +1170,13 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 			return -ENOENT;
 		}
 
-		err = call_fib6_entry_notifiers(info->nl_net,
-						FIB_EVENT_ENTRY_REPLACE,
-						rt, extack);
-		if (err)
-			return err;
+		if (!info->skip_notify_kernel) {
+			err = call_fib6_entry_notifiers(info->nl_net,
+							FIB_EVENT_ENTRY_REPLACE,
+							rt, extack);
+			if (err)
+				return err;
+		}
 
 		fib6_info_hold(rt);
 		rcu_assign_pointer(rt->fib6_node, fn);
@@ -1839,9 +1859,11 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
 
 	fib6_purge_rt(rt, fn, net);
 
-	call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
+	if (!info->skip_notify_kernel)
+		call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
 	if (!info->skip_notify)
 		inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
+
 	fib6_info_release(rt);
 }
 

net/ipv6/route.c

@@ -3718,6 +3718,12 @@ static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
 				info->skip_notify = 1;
 		}
 
+		info->skip_notify_kernel = 1;
+		call_fib6_multipath_entry_notifiers(net,
+						    FIB_EVENT_ENTRY_DEL,
+						    rt,
+						    rt->fib6_nsiblings,
+						    NULL);
 		list_for_each_entry_safe(sibling, next_sibling,
 					 &rt->fib6_siblings,
 					 fib6_siblings) {
@@ -4965,6 +4971,7 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
 {
 	struct fib6_info *rt_notif = NULL, *rt_last = NULL;
 	struct nl_info *info = &cfg->fc_nlinfo;
+	enum fib_event_type event_type;
 	struct fib6_config r_cfg;
 	struct rtnexthop *rtnh;
 	struct fib6_info *rt;
@@ -5042,6 +5049,11 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
 	 */
 	info->skip_notify = 1;
 
+	/* For add and replace, send one notification with all nexthops. For
+	 * append, send one notification with all appended nexthops.
+	 */
+	info->skip_notify_kernel = 1;
+
 	err_nh = NULL;
 	list_for_each_entry(nh, &rt6_nh_list, next) {
 		err = __ip6_ins_rt(nh->fib6_info, info, extack);
@@ -5078,6 +5090,15 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
 		nhn++;
 	}
 
+	event_type = replace ? FIB_EVENT_ENTRY_REPLACE : FIB_EVENT_ENTRY_ADD;
+	err = call_fib6_multipath_entry_notifiers(info->nl_net, event_type,
+						  rt_notif, nhn - 1, extack);
+	if (err) {
+		/* Delete all the siblings that were just added */
+		err_nh = NULL;
+		goto add_errout;
+	}
+
 	/* success ... tell user about new route */
 	ip6_route_mpath_notify(rt_notif, rt_last, info, nlflags);
 	goto cleanup;