From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Jason Wang <jasowang@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: mst@redhat.com, christoffer.dall@linaro.org
Subject: Re: [PATCH net v2 2/2] tuntap: correctly add the missing xdp flush
Date: Thu, 22 Feb 2018 10:54:30 +0300 [thread overview]
Message-ID: <0bb9796e-5f52-dc9a-b7c2-6628bca712ed@cogentembedded.com> (raw)
In-Reply-To: <1519280658-4918-2-git-send-email-jasowang@redhat.com>
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@linaro.org>
> Fixes: 762c330d670e ("tuntap: add missing xdp flush")
> Signed-off-by: Jason Wang <jasowang@redhat.com>
[...]
MBR, Sergei
next prev parent reply other threads:[~2018-02-22 7:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-22 6:24 [PATCH net v2 1/2] Revert "tuntap: add missing xdp flush" Jason Wang
2018-02-22 6:24 ` [PATCH net v2 2/2] tuntap: correctly add the missing xdp flush Jason Wang
2018-02-22 7:54 ` Sergei Shtylyov [this message]
2018-02-22 9:35 ` Jason Wang
2018-02-22 7:57 ` [PATCH net v2 1/2] Revert "tuntap: add missing xdp flush" Sergei Shtylyov
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