Re: [PATCH net v2 2/2] tuntap: correctly add the missing xdp flush

[Sergei Shtylyov]

Hello!

On 2/22/2018 9:24 AM, Jason Wang wrote:

> Commit 762c330d670e ("tuntap: add missing xdp flush") tries to fix the
> devmap stall caused by missed xdp flush by counting the pending xdp
> redirected packets and flush when it exceeds NAPI_POLL_WEIGHT or
> MSG_MORE is clear. This may lead BUG() since xdp_do_flush() was

   Lead to BUG().

> called under process context with preemption enabled. Simply disable

   s/under/in the/?

> preemption may silent the warning but be not enough since process may

   Silence.

> move between different CPUS during a batch which cause xdp_do_flush()
> misses some CPU where the process run previously. Consider the several
> fallouts, that commit was reverted. To fix the issue correctly, we can
> simply calling xdp_do_flush() immediately after xdp_do_redirect(),

   Call.

> a side effect is that this removes any possibility of batching which
> could be addressed in the future.
>
> Reported-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> Fixes: 762c330d670e ("tuntap: add missing xdp flush")
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
[...]

MBR, Sergei