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

[Jason Wang]

On 2018å02æ22æ 15:54, Sergei Shtylyov wrote:
> 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
>
> ÂÂ Lead to BUG().
>
> > called under process context with preemption enabled. Simply disable
>
> ÂÂ s/under/in the/?
>
> > preemption may silent the warning but be not enough since process may
>
> ÂÂ 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(),
>
> ÂÂ 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

My bad, let me post v3.

Thanks