bonding/802.3ad: fix link_failure_count tracking

Commit 4d2c0cda set slave->link to
BOND_LINK_DOWN for 802.3ad bonds whenever invalid speed/duplex values
were read, to fix a problem with slaves getting into weird states, but
in the process, broke tracking of link failures, as going straight to
BOND_LINK_DOWN when a link is indeed down (cable pulled, switch rebooted)
means we broke out of bond_miimon_inspect()'s BOND_LINK_DOWN case because
!link_state was already true, we never incremented commit, and never got
a chance to call bond_miimon_commit(), where slave->link_failure_count
would be incremented. I believe the simple fix here is to mark the slave
as BOND_LINK_FAIL, and let bond_miimon_inspect() transition the link from
_FAIL to either _UP or _DOWN, and in the latter case, we now get proper
incrementing of link_failure_count again.

Fixes: 4d2c0cda ("bonding: speed/duplex update at NETDEV_UP event")
CC: Mahesh Bandewar <maheshb@google.com>
CC: David S. Miller <davem@davemloft.net>
CC: netdev@vger.kernel.org
CC: stable@vger.kernel.org
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -3112,13 +3112,13 @@ static int bond_slave_netdev_event(unsigned long event,
 	case NETDEV_CHANGE:
 		/* For 802.3ad mode only:
 		 * Getting invalid Speed/Duplex values here will put slave
-		 * in weird state. So mark it as link-down for the time
+		 * in weird state. So mark it as link-fail for the time
 		 * being and let link-monitoring (miimon) set it right when
 		 * correct speeds/duplex are available.
 		 */
 		if (bond_update_speed_duplex(slave) &&
 		    BOND_MODE(bond) == BOND_MODE_8023AD)
-			slave->link = BOND_LINK_DOWN;
+			slave->link = BOND_LINK_FAIL;
 
 		if (BOND_MODE(bond) == BOND_MODE_8023AD)
 			bond_3ad_adapter_speed_duplex_changed(slave);