net: Add notifications when multipath hash field change

In-kernel notifications are already sent when the multipath hash policy
itself changes, but not when the multipath hash fields change.

Add these notifications, so that interested listeners (e.g., switch ASIC
drivers) could perform the necessary configuration.
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Reviewed-by: NPetr Machata <petrm@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/sysctl_net_ipv4.c

@@ -465,6 +465,22 @@ static int proc_fib_multipath_hash_policy(struct ctl_table *table, int write,
 
 	return ret;
 }
+
+static int proc_fib_multipath_hash_fields(struct ctl_table *table, int write,
+					  void *buffer, size_t *lenp,
+					  loff_t *ppos)
+{
+	struct net *net;
+	int ret;
+
+	net = container_of(table->data, struct net,
+			   ipv4.sysctl_fib_multipath_hash_fields);
+	ret = proc_douintvec_minmax(table, write, buffer, lenp, ppos);
+	if (write && ret == 0)
+		call_netevent_notifiers(NETEVENT_IPV4_MPATH_HASH_UPDATE, net);
+
+	return ret;
+}
 #endif
 
 static struct ctl_table ipv4_table[] = {
@@ -1061,7 +1077,7 @@ static struct ctl_table ipv4_net_table[] = {
 		.data		= &init_net.ipv4.sysctl_fib_multipath_hash_fields,
 		.maxlen		= sizeof(u32),
 		.mode		= 0644,
-		.proc_handler	= proc_douintvec_minmax,
+		.proc_handler	= proc_fib_multipath_hash_fields,
 		.extra1		= SYSCTL_ONE,
 		.extra2		= &fib_multipath_hash_fields_all_mask,
 	},

net/ipv6/sysctl_net_ipv6.c

@@ -44,6 +44,22 @@ static int proc_rt6_multipath_hash_policy(struct ctl_table *table, int write,
 	return ret;
 }
 
+static int
+proc_rt6_multipath_hash_fields(struct ctl_table *table, int write, void *buffer,
+			       size_t *lenp, loff_t *ppos)
+{
+	struct net *net;
+	int ret;
+
+	net = container_of(table->data, struct net,
+			   ipv6.sysctl.multipath_hash_fields);
+	ret = proc_douintvec_minmax(table, write, buffer, lenp, ppos);
+	if (write && ret == 0)
+		call_netevent_notifiers(NETEVENT_IPV6_MPATH_HASH_UPDATE, net);
+
+	return ret;
+}
+
 static struct ctl_table ipv6_table_template[] = {
 	{
 		.procname	= "bindv6only",
@@ -160,7 +176,7 @@ static struct ctl_table ipv6_table_template[] = {
 		.data		= &init_net.ipv6.sysctl.multipath_hash_fields,
 		.maxlen		= sizeof(u32),
 		.mode		= 0644,
-		.proc_handler	= proc_douintvec_minmax,
+		.proc_handler	= proc_rt6_multipath_hash_fields,
 		.extra1		= SYSCTL_ONE,
 		.extra2		= &rt6_multipath_hash_fields_all_mask,
 	},