bonding: handle BOND_LINK_FAIL, BOND_LINK_BACK as valid link states

Before the fixed commit, we check slave->new_link during commit
state, which values are only BOND_LINK_{NOCHANGE, UP, DOWN}. After
the commit, we start using slave->link_new_state, which state also could
be BOND_LINK_{FAIL, BACK}.

For example, when we set updelay/downdelay, after a failover,
the slave->link_new_state could be set to BOND_LINK_{FAIL, BACK} in
bond_miimon_inspect(). And later in bond_miimon_commit(), it will treat
it as invalid and print an error, which would cause confusion for users.

[  106.440254] bond0: (slave veth2): link status down for interface, disabling it in 200 ms
[  106.440265] bond0: (slave veth2): invalid new link 1 on slave
[  106.648276] bond0: (slave veth2): link status definitely down, disabling slave
[  107.480271] bond0: (slave veth2): link status up, enabling it in 200 ms
[  107.480288] bond0: (slave veth2): invalid new link 3 on slave
[  107.688302] bond0: (slave veth2): link status definitely up, 10000 Mbps full duplex

Let's handle BOND_LINK_{FAIL, BACK} as valid link states.

Fixes: 1899bb3 ("bonding: fix state transition issue in link monitoring")
Signed-off-by: Hangbin Liu <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: liuhangbin

drivers/net/bonding/bond_main.c

@@ -2801,8 +2801,14 @@ static void bond_miimon_commit(struct bonding *bond)
 
 			continue;
 
+		case BOND_LINK_FAIL:
+		case BOND_LINK_BACK:
+			slave_dbg(bond->dev, slave->dev, "link_new_state %d on slave\n",
+				  slave->link_new_state);
+			continue;
+
 		default:
-			slave_err(bond->dev, slave->dev, "invalid new link %d on slave\n",
+			slave_err(bond->dev, slave->dev, "invalid link_new_state %d on slave\n",
 				  slave->link_new_state);
 			bond_propose_link_state(slave, BOND_LINK_NOCHANGE);