[PATCH 5.1 01/40] bonding/802.3ad: fix slave link initialization transition states

From: Greg Kroah-Hartman
Date: Mon Jun 03 2019 - 05:16:45 EST

From: Jarod Wilson <jarod@xxxxxxxxxx>

[ Upstream commit 334031219a84b9994594015aab85ed7754c80176 ]

Once in a while, with just the right timing, 802.3ad slaves will fail to
properly initialize, winding up in a weird state, with a partner system
mac address of 00:00:00:00:00:00. This started happening after a fix to
properly track link_failure_count tracking, where an 802.3ad slave that
reported itself as link up in the miimon code, but wasn't able to get a
valid speed/duplex, started getting set to BOND_LINK_FAIL instead of
BOND_LINK_DOWN. That was the proper thing to do for the general "my link
went down" case, but has created a link initialization race that can put
the interface in this odd state.

The simple fix is to instead set the slave link to BOND_LINK_DOWN again,
if the link has never been up (last_link_up == 0), so the link state
doesn't bounce from BOND_LINK_DOWN to BOND_LINK_FAIL -- it hasn't failed
in this case, it simply hasn't been up yet, and this prevents the
unnecessary state change from DOWN to FAIL and getting stuck in an init
failure w/o a partner mac.

Fixes: ea53abfab960 ("bonding/802.3ad: fix link_failure_count tracking")
CC: Jay Vosburgh <j.vosburgh@xxxxxxxxx>
CC: Veaceslav Falico <vfalico@xxxxxxxxx>
CC: Andy Gospodarek <andy@xxxxxxxxxxxxx>
CC: "David S. Miller" <davem@xxxxxxxxxxxxx>
CC: netdev@xxxxxxxxxxxxxxx
Tested-by: Heesoon Kim <Heesoon.Kim@xxxxxxxxxxx>
Signed-off-by: Jarod Wilson <jarod@xxxxxxxxxx>
Acked-by: Jay Vosburgh <jay.vosburgh@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/bonding/bond_main.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3122,13 +3122,18 @@ static int bond_slave_netdev_event(unsig
/* For 802.3ad mode only:
* Getting invalid Speed/Duplex values here will put slave
- * 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.
+ * in weird state. Mark it as link-fail if the link was
+ * previously up or link-down if it hasn't yet come up, 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_FAIL;
+ BOND_MODE(bond) == BOND_MODE_8023AD) {
+ if (slave->last_link_up)
+ slave->link = BOND_LINK_FAIL;
+ else
+ slave->link = BOND_LINK_DOWN;
+ }

if (BOND_MODE(bond) == BOND_MODE_8023AD)