From: Hangbin Liu When bond_enslave() succeeds up to the XDP setup stage, slave_cnt is already incremented. If XDP setup subsequently fails, the error paths jump directly to err_sysfs_del, bypassing the slave_cnt decrement. This causes slave_cnt to drift upward on each failed enslaving attempt, which would lead to unbalanced traffic distribution with round-robin mode. Add an error out to make sure slave_cnt gets decreased correctly. Fixes: 9e2ee5c7e7c3 ("net, bonding: Add XDP support to the bonding driver") Signed-off-by: Hangbin Liu --- Changes in v4: - Revert to v1 version as the bond_select_active_slave() just under slave_cnt increase also calls bond_update_slave_arr() (sashiko) - re-run all bonding selftests with debug kernel, all passed. - Link to v3: https://lore.kernel.org/r/20260907-bond_slave_cnt-v3-1-57df3b3cf2cb@kylinos.cn Changes in v3: - move the slave_cnt increasement before bond_update_slave_arr() (selftest) - run all bonding selftests on debug kernel to make sure no regression (Jakub) - Link to v2: https://lore.kernel.org/r/20260903-bond_slave_cnt-v2-1-02e27304ca36@kylinos.cn Changes in v2: - move the slave_cnt increasement after XDP setup (Nikolay Aleksandrov) - balance-xor mode is not affected, not mention it (Nikolay Aleksandrov) - Link to v1: https://lore.kernel.org/r/20260902-bond_slave_cnt-v1-1-36e95bf4a6ff@kylinos.cn --- drivers/net/bonding/bond_main.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index a9bff7663eec..577d85c83804 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2305,7 +2305,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, SLAVE_NL_ERR(bond_dev, slave_dev, extack, "Slave does not support XDP"); res = -EOPNOTSUPP; - goto err_sysfs_del; + goto err_slave_cnt; } } else if (bond->xdp_prog) { struct netdev_bpf xdp = { @@ -2319,14 +2319,14 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, SLAVE_NL_ERR(bond_dev, slave_dev, extack, "Slave has XDP program loaded, please unload before enslaving"); res = -EOPNOTSUPP; - goto err_sysfs_del; + goto err_slave_cnt; } res = dev_xdp_propagate(slave_dev, &xdp); if (res < 0) { /* ndo_bpf() sets extack error message */ slave_dbg(bond_dev, slave_dev, "Error %d calling ndo_bpf\n", res); - goto err_sysfs_del; + goto err_slave_cnt; } if (bond->xdp_prog) bpf_prog_inc(bond->xdp_prog); @@ -2348,6 +2348,9 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, return 0; /* Undo stages on error */ +err_slave_cnt: + WRITE_ONCE(bond->slave_cnt, bond->slave_cnt - 1); + err_sysfs_del: bond_sysfs_slave_del(new_slave); --- base-commit: e6b6078ea1731b05b3b552497b3bce4bf8b014ae change-id: 20260807-bond_slave_cnt-88e78c5f0ab9 Best regards, -- Hangbin Liu