Re: [PATCH net v4] bonding: fix slave_cnt leak on XDP error paths

[Nikolay Aleksandrov]

On 14/09/2026 06:09, Hangbin Liu wrote:
> From: Hangbin Liu <liuhangbin@xxxxxxxxxx>
>
> 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 <liuhangbin@xxxxxxxxxx>
> ---
> 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@xxxxxxxxxx
>
> 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@xxxxxxxxxx
>
> 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@xxxxxxxxxx
> ---
>   drivers/net/bonding/bond_main.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)

Reviewed-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>