Subject: Re: [PATCH net] bonding: fix active-backup transition after link failure

From: Jay Vosburgh <[email-masked]>
Date: Sat, 07 Dec 2019 14:09:52 -0800

Mahesh Bandewar <[email-masked]> wrote:

>After the recent fix 1899bb325149 ("bonding: fix state transition
>issue in link monitoring"), the active-backup mode with miimon
>initially come-up fine but after a link-failure, both members
>transition into backup state.
>
>Following steps to reproduce the scenario (eth1 and eth2 are the
>slaves of the bond):
>
>    ip link set eth1 up
>    ip link set eth2 down
>    sleep 1
>    ip link set eth2 up
>    ip link set eth1 down
>    cat /sys/class/net/eth1/bonding_slave/state
>    cat /sys/class/net/eth2/bonding_slave/state
>
>Fixes: 1899bb325149 ("bonding: fix state transition issue in link monitoring")
>CC: Jay Vosburgh <[email-masked]>
>Signed-off-by: Mahesh Bandewar <[email-masked]>
>---
> drivers/net/bonding/bond_main.c | 3 ---
> 1 file changed, 3 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index fcb7c2f7f001..ad9906c102b4 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -2272,9 +2272,6 @@ static void bond_miimon_commit(struct bonding *bond)
> 			} else if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
> 				/* make it immediately active */
> 				bond_set_active_slave(slave);
>-			} else if (slave != primary) {
>-				/* prevent it from being the active one */
>-				bond_set_backup_slave(slave);

	How does this fix things?  Doesn't bond_select_active_slave() ->
bond_change_active_slave() set the backup flag correctly via a call to
bond_set_slave_active_flags() when it sets a slave to be the active
slave?  If this change resolves the problem, I'm not sure how this ever
worked correctly, even prior to 1899bb325149.

	-J

> 			}
> 
> 			slave_info(bond->dev, slave->dev, "link status definitely up, %u Mbps %s duplex\n",
>-- 
>2.24.0.393.g34dc348eaf-goog
>

---
	-Jay Vosburgh, [email-masked]