net: ntb_netdev: Fix statistics races

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.

Let the core manage tstats while keeping transport teardown after
unregister_netdev(), outside RTNL. RCU lets unregister wait for TX
completions already updating stats, while later completions only consume
the skb and skip accounting and queue wake.

Fixes: 24d9e73c7e00 ("net: ntb_netdev: Support ethtool channels for multi-queue")
Cc: stable@vger.kernel.org
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260830151617.3546585-1-den@valinux.co.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions