Re: [PATCH net v2] net: ntb_netdev: Fix statistics races

[Eric Dumazet]

On Fri, Aug 28, 2026 at 5:41 PM Koichiro Den <den@xxxxxxxxxxxxx> wrote:
>
> ntb_netdev updates shared net_device stats from per-QP RX and TX
> callbacks. Once multiple queues are enabled, concurrent updates can be
> lost.
>
> Use per-CPU tstats for packet and byte counters and DEV_STATS_INC() for
> less frequent drop and error counters. Callbacks can run synchronously
> in the xmit path or asynchronously from a tasklet or the memcpy kthread.
> Pin TX updates against migration in the kthread path. Use the IRQ-safe
> u64_stats helpers because netpoll can invoke the synchronous path with
> IRQs disabled.
>
> Note that transport callbacks may still complete after
> unregister_netdev(), so tie the tstats lifetime to the client device.
>
> Fixes: 24d9e73c7e00 ("net: ntb_netdev: Support ethtool channels for multi-queue")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>

Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>