Re: [PATCH net 2/2] virtio_net: mask callbacks before releasing NAPI ownership

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] virtio_net: missing Fixes trailer for virtqueue_napi_complete()
  race fix
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commit c4014f837fc88f44df9c4728b3bea8a252b5c2fb
Author: Congjie Zhou <zcjie0802@qq.com>

> virtio_net: mask callbacks before releasing NAPI ownership
>
> virtqueue_napi_complete() prepares callbacks before calling
> napi_complete_done(), then disables them if completion returns false.
> On the hard IRQ deferral path, completion can release NAPI ownership
> and arm the watchdog before returning false.
>
> A successor poll can rearm callbacks and complete before the old caller
> executes virtqueue_disable_cb(). The stale mask then disables
> notifications again. If the one-shot watchdog has already run, no NAPI
> owner or timer remains to consume later used entries, causing a
> persistent RX stall.
>
> Use napi_complete_done_with_irq_mask() to disable callbacks before
> completion can hand NAPI to a successor, and remove the stale mask after
> a false return. Keep virtqueue_enable_cb_prepare() before completion:
> moving it after ownership release would reintroduce the RX virtqueue
> race fixed by commit cbdadbbf0c79 ("virtio_net: fix race in RX VQ
> processing").
>
> Signed-off-by: Congjie Zhou <zcjie0802@qq.com>

[Severity: Low]
This fixes a persistent RX stall race in virtqueue_napi_complete().
Should it include a Fixes tag for the post-completion virtqueue_disable_cb()
call?

  Fixes: fdaa767aefc1 ("virtio_net: Disable interrupts if napi_complete_done rescheduled napi")

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Sashiko AI review · https://sashiko.dev/#/patchset/tencent_74EA7A2E8BF5758E9C5EF18C9B1CED401D06@qq.com?part=2