netdev - [RFC PATCH net-next 3/5] nexthop: add support for notifiers

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Message-Id: <1588631301-21564-4-git-send-email-roopa@cumulusnetworks.com>
Date:   Mon,  4 May 2020 15:28:19 -0700
From:   Roopa Prabhu <roopa@...ulusnetworks.com>
To:     dsahern@...il.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, nikolay@...ulusnetworks.com,
        idosch@...lanox.com, jiri@...lanox.com, petrm@...lanox.com
Subject: [RFC PATCH net-next 3/5] nexthop: add support for notifiers

From: Roopa Prabhu <roopa@...ulusnetworks.com>

This patch adds nexthop add/del notifiers. To be used by
vxlan driver in a later patch. Could possibly be used by
switchdev drivers in the future.

Signed-off-by: Roopa Prabhu <roopa@...ulusnetworks.com>
---
 include/net/netns/nexthop.h |  1 +
 include/net/nexthop.h       | 12 ++++++++++++
 net/ipv4/nexthop.c          | 27 +++++++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/include/net/netns/nexthop.h b/include/net/netns/nexthop.h
index c712ee5..1937476 100644
--- a/include/net/netns/nexthop.h
+++ b/include/net/netns/nexthop.h
@@ -14,5 +14,6 @@ struct netns_nexthop {
 
 	unsigned int		seq;		/* protected by rtnl_mutex */
 	u32			last_id_allocated;
+	struct atomic_notifier_head notifier_chain;
 };
 #endif
diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 3ad4e97..0301740 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -10,6 +10,7 @@
 #define __LINUX_NEXTHOP_H
 
 #include <linux/netdevice.h>
+#include <linux/notifier.h>
 #include <linux/route.h>
 #include <linux/types.h>
 #include <net/ip_fib.h>
@@ -102,6 +103,17 @@ struct nexthop {
 	};
 };
 
+enum nexthop_event_type {
+	NEXTHOP_EVENT_ADD,
+	NEXTHOP_EVENT_DEL
+};
+
+int call_nexthop_notifier(struct notifier_block *nb, struct net *net,
+			  enum nexthop_event_type event_type,
+			  struct nexthop *nh);
+int register_nexthop_notifier(struct notifier_block *nb);
+int unregister_nexthop_notifier(struct notifier_block *nb);
+
 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 void nexthop_free_rcu(struct rcu_head *head);
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 98f8d2a..514bb4e 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -36,6 +36,17 @@ static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = {
 	[NHA_FDB]		= { .type = NLA_FLAG },
 };
 
+static int call_nexthop_notifiers(struct net *net,
+				  enum fib_event_type event_type,
+				  struct nexthop *nh)
+{
+	int err;
+
+	err = atomic_notifier_call_chain(&net->nexthop.notifier_chain,
+					 event_type, nh);
+	return notifier_to_errno(err);
+}
+
 static unsigned int nh_dev_hashfn(unsigned int val)
 {
 	unsigned int mask = NH_DEV_HASHSIZE - 1;
@@ -814,6 +825,8 @@ static void __remove_nexthop_fib(struct net *net, struct nexthop *nh)
 		ipv6_stub->ip6_del_rt(net, f6i,
 				      !net->ipv4.sysctl_nexthop_compat_mode);
 	}
+
+	call_nexthop_notifiers(net, NEXTHOP_EVENT_DEL, nh);
 }
 
 static void __remove_nexthop(struct net *net, struct nexthop *nh,
@@ -1838,6 +1851,20 @@ static struct notifier_block nh_netdev_notifier = {
 	.notifier_call = nh_netdev_event,
 };
 
+static ATOMIC_NOTIFIER_HEAD(nexthop_notif_chain);
+
+int register_nexthop_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&nexthop_notif_chain, nb);
+}
+EXPORT_SYMBOL(register_nexthop_notifier);
+
+int unregister_nexthop_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&nexthop_notif_chain, nb);
+}
+EXPORT_SYMBOL(unregister_nexthop_notifier);
+
 static void __net_exit nexthop_net_exit(struct net *net)
 {
 	rtnl_lock();
-- 
2.1.4