Merge branch 'mtu-related-changes'

Stephen Hemminger says:

====================
mtu related changes

While looking at other MTU issues, noticed a couple oppurtunties
for improving user experience.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/net_failover.c

@@ -220,14 +220,14 @@ static int net_failover_change_mtu(struct net_device *dev, int new_mtu)
 	struct net_device *primary_dev, *standby_dev;
 	int ret = 0;
 
-	primary_dev = rcu_dereference(nfo_info->primary_dev);
+	primary_dev = rtnl_dereference(nfo_info->primary_dev);
 	if (primary_dev) {
 		ret = dev_set_mtu(primary_dev, new_mtu);
 		if (ret)
 			return ret;
 	}
 
-	standby_dev = rcu_dereference(nfo_info->standby_dev);
+	standby_dev = rtnl_dereference(nfo_info->standby_dev);
 	if (standby_dev) {
 		ret = dev_set_mtu(standby_dev, new_mtu);
 		if (ret) {

include/linux/netdevice.h

@@ -3546,6 +3546,8 @@ int dev_set_alias(struct net_device *, const char *, size_t);
 int dev_get_alias(const struct net_device *, char *, size_t);
 int dev_change_net_namespace(struct net_device *, struct net *, const char *);
 int __dev_set_mtu(struct net_device *, int);
+int dev_set_mtu_ext(struct net_device *dev, int mtu,
+		    struct netlink_ext_ack *extack);
 int dev_set_mtu(struct net_device *, int);
 int dev_change_tx_queue_len(struct net_device *, unsigned long);
 void dev_set_group(struct net_device *, int);

include/uapi/linux/if_link.h

@@ -164,6 +164,8 @@ enum {
 	IFLA_CARRIER_UP_COUNT,
 	IFLA_CARRIER_DOWN_COUNT,
 	IFLA_NEW_IFINDEX,
+	IFLA_MIN_MTU,
+	IFLA_MAX_MTU,
 	__IFLA_MAX
 };
 

net/core/dev.c

@@ -7523,13 +7523,15 @@ int __dev_set_mtu(struct net_device *dev, int new_mtu)
 EXPORT_SYMBOL(__dev_set_mtu);
 
 /**
- *	dev_set_mtu - Change maximum transfer unit
+ *	dev_set_mtu_ext - Change maximum transfer unit
  *	@dev: device
  *	@new_mtu: new transfer unit
+ *	@extack: netlink extended ack
  *
  *	Change the maximum transfer size of the network device.
  */
-int dev_set_mtu(struct net_device *dev, int new_mtu)
+int dev_set_mtu_ext(struct net_device *dev, int new_mtu,
+		    struct netlink_ext_ack *extack)
 {
 	int err, orig_mtu;
 
@@ -7538,14 +7540,12 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
 
 	/* MTU must be positive, and in range */
 	if (new_mtu < 0 || new_mtu < dev->min_mtu) {
-		net_err_ratelimited("%s: Invalid MTU %d requested, hw min %d\n",
-				    dev->name, new_mtu, dev->min_mtu);
+		NL_SET_ERR_MSG(extack, "mtu less than device minimum");
 		return -EINVAL;
 	}
 
 	if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) {
-		net_err_ratelimited("%s: Invalid MTU %d requested, hw max %d\n",
-				    dev->name, new_mtu, dev->max_mtu);
+		NL_SET_ERR_MSG(extack, "mtu greater than device maximum");
 		return -EINVAL;
 	}
 
@@ -7573,6 +7573,17 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
 	}
 	return err;
 }
+
+int dev_set_mtu(struct net_device *dev, int new_mtu)
+{
+	struct netlink_ext_ack extack;
+	int err;
+
+	err = dev_set_mtu_ext(dev, new_mtu, &extack);
+	if (err)
+		net_err_ratelimited("%s: %s\n", dev->name, extack._msg);
+	return err;
+}
 EXPORT_SYMBOL(dev_set_mtu);
 
 /**

net/core/rtnetlink.c

@@ -1015,6 +1015,8 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
 	       + nla_total_size(4)  /* IFLA_IF_NETNSID */
 	       + nla_total_size(4)  /* IFLA_CARRIER_UP_COUNT */
 	       + nla_total_size(4)  /* IFLA_CARRIER_DOWN_COUNT */
+	       + nla_total_size(4)  /* IFLA_MIN_MTU */
+	       + nla_total_size(4)  /* IFLA_MAX_MTU */
 	       + 0;
 }
 
@@ -1601,6 +1603,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
 		       netif_running(dev) ? dev->operstate : IF_OPER_DOWN) ||
 	    nla_put_u8(skb, IFLA_LINKMODE, dev->link_mode) ||
 	    nla_put_u32(skb, IFLA_MTU, dev->mtu) ||
+	    nla_put_u32(skb, IFLA_MIN_MTU, dev->min_mtu) ||
+	    nla_put_u32(skb, IFLA_MAX_MTU, dev->max_mtu) ||
 	    nla_put_u32(skb, IFLA_GROUP, dev->group) ||
 	    nla_put_u32(skb, IFLA_PROMISCUITY, dev->promiscuity) ||
 	    nla_put_u32(skb, IFLA_NUM_TX_QUEUES, dev->num_tx_queues) ||
@@ -1732,6 +1736,8 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
 	[IFLA_IF_NETNSID]	= { .type = NLA_S32 },
 	[IFLA_CARRIER_UP_COUNT]	= { .type = NLA_U32 },
 	[IFLA_CARRIER_DOWN_COUNT] = { .type = NLA_U32 },
+	[IFLA_MIN_MTU]		= { .type = NLA_U32 },
+	[IFLA_MAX_MTU]		= { .type = NLA_U32 },
 };
 
 static const struct nla_policy ifla_info_policy[IFLA_INFO_MAX+1] = {
@@ -2376,7 +2382,7 @@ static int do_setlink(const struct sk_buff *skb,
 	}
 
 	if (tb[IFLA_MTU]) {
-		err = dev_set_mtu(dev, nla_get_u32(tb[IFLA_MTU]));
+		err = dev_set_mtu_ext(dev, nla_get_u32(tb[IFLA_MTU]), extack);
 		if (err < 0)
 			goto errout;
 		status |= DO_SETLINK_MODIFIED;