Re: [PATCH net v5 2/2] bonding: fix u32 overflow in compute_gap()

[Nikolay Aleksandrov]

On 25/08/2026 04:01, Hangbin Liu wrote:
> From: Hangbin Liu <liuhangbin@xxxxxxxxxx>
>
> The TLB load-tracking fields tx_bytes, load_history, load, and
> unbalanced_load are all u32. At sustained throughput above ~3.2 Gbit/s
> over the 10-second rebalance interval the byte counters wrap, causing
> compute_gap() to produce incorrect gap values and mis-select slaves.
> Such speeds are common on modern NICs under heavy traffic.
>
> Widen these fields to u64. Use u64_stats_sync to protect the per-cpu
> unbalanced_load_stats against tearing on 32-bit architectures, and
> div_u64() for the 64-bit divisions. The tx_bytes and load_history
> are protected in spin_lock. Also protect the slave load writing in
> bond_alb_monitor() with spin_lock in case of tear on 32-bit.
>
> Rework compute_gap() to use s64 arithmetic throughout. Return LLONG_MIN
> when the speed is unknown.
>
> Detected by AI code review.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxxx>
> ---
>   drivers/net/bonding/bond_alb.c | 52 ++++++++++++++++++++++++++++++------------
>   include/net/bond_alb.h         | 11 +++++----
>   2 files changed, 44 insertions(+), 19 deletions(-)

Reviewed-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>