bonding: add an option to specify a delay between peer notifications

Currently, gratuitous ARP/ND packets are sent every `miimon'
milliseconds. This commit allows a user to specify a custom delay
through a new option, `peer_notif_delay'.

Like for `updelay' and `downdelay', this delay should be a multiple of
`miimon' to avoid managing an additional work queue. The configuration
logic is copied from `updelay' and `downdelay'. However, the default
value cannot be set using a module parameter: Netlink or sysfs should
be used to configure this feature.

When setting `miimon' to 100 and `peer_notif_delay' to 500, we can
observe the 500 ms delay is respected:

    20:30:19.354693 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
    20:30:19.874892 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
    20:30:20.394919 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
    20:30:20.914963 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28

In bond_mii_monitor(), I have tried to keep the lock logic readable.
The change is due to the fact we cannot rely on a notification to
lower the value of `bond->send_peer_notif' as `NETDEV_NOTIFY_PEERS' is
only triggered once every N times, while we need to decrement the
counter each time.

iproute2 also needs to be updated to be able to specify this new
attribute through `ip link'.

Signed-off-by: Vincent Bernat <vincent@bernat.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
index b24cce48ae35..a259860a7208 100644
--- a/drivers/net/bonding/bond_netlink.c
+++ b/drivers/net/bonding/bond_netlink.c
@@ -108,6 +108,7 @@ static const struct nla_policy bond_policy[IFLA_BOND_MAX + 1] = {
 	[IFLA_BOND_AD_ACTOR_SYSTEM]	= { .type = NLA_BINARY,
 					    .len  = ETH_ALEN },
 	[IFLA_BOND_TLB_DYNAMIC_LB]	= { .type = NLA_U8 },
+	[IFLA_BOND_PEER_NOTIF_DELAY]    = { .type = NLA_U32 },
 };
 
 static const struct nla_policy bond_slave_policy[IFLA_BOND_SLAVE_MAX + 1] = {
@@ -215,6 +216,14 @@ static int bond_changelink(struct net_device *bond_dev, struct nlattr *tb[],
 		if (err)
 			return err;
 	}
+	if (data[IFLA_BOND_PEER_NOTIF_DELAY]) {
+		int delay = nla_get_u32(data[IFLA_BOND_PEER_NOTIF_DELAY]);
+
+		bond_opt_initval(&newval, delay);
+		err = __bond_opt_set(bond, BOND_OPT_PEER_NOTIF_DELAY, &newval);
+		if (err)
+			return err;
+	}
 	if (data[IFLA_BOND_USE_CARRIER]) {
 		int use_carrier = nla_get_u8(data[IFLA_BOND_USE_CARRIER]);
 
@@ -494,6 +503,7 @@ static size_t bond_get_size(const struct net_device *bond_dev)
 		nla_total_size(sizeof(u16)) + /* IFLA_BOND_AD_USER_PORT_KEY */
 		nla_total_size(ETH_ALEN) + /* IFLA_BOND_AD_ACTOR_SYSTEM */
 		nla_total_size(sizeof(u8)) + /* IFLA_BOND_TLB_DYNAMIC_LB */
+		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_PEER_NOTIF_DELAY */
 		0;
 }
 
@@ -536,6 +546,10 @@ static int bond_fill_info(struct sk_buff *skb,
 			bond->params.downdelay * bond->params.miimon))
 		goto nla_put_failure;
 
+	if (nla_put_u32(skb, IFLA_BOND_PEER_NOTIF_DELAY,
+			bond->params.downdelay * bond->params.miimon))
+		goto nla_put_failure;
+
 	if (nla_put_u8(skb, IFLA_BOND_USE_CARRIER, bond->params.use_carrier))
 		goto nla_put_failure;