From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Hou Tao <houtao@huaweicloud.com>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Paolo Abeni <pabeni@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andrii Nakryiko <andrii@kernel.org>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, KP Singh <kpsingh@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Stanislav Fomichev <sdf@google.com>,
Yonghong Song <yonghong.song@linux.dev>
Subject: Re: [PATCH net 4/4] bpf, cpumap: Flush xdp after cpu_map_bpf_prog_run_skb().
Date: Mon, 11 Sep 2023 08:50:16 +0200 [thread overview]
Message-ID: <20230911065016.IkkQJSfN@linutronix.de> (raw)
In-Reply-To: <1cf255a3-e48b-0a90-28ce-1a9c47095fc2@huaweicloud.com>
On 2023-09-09 10:49:09 [+0800], Hou Tao wrote:
> Hi,
Hi,
> > --- a/kernel/bpf/cpumap.c
> > +++ b/kernel/bpf/cpumap.c
> > @@ -248,12 +248,12 @@ static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames,
> >
> > nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats);
> >
> > - if (stats->redirect)
> > - xdp_do_flush();
> > -
> > if (unlikely(!list_empty(list)))
> > cpu_map_bpf_prog_run_skb(rcpu, list, stats);
> >
> > + if (stats->redirect)
> > + xdp_do_flush();
> > +
>
> The purpose of xdp_do_flush() is to flush xdp frames stashed in per-cpu
> cpu_map_flush list into xdp_bulk_queue. But for redirected skbs, these
> skbs will be directly added into xdp_bulk_queue() in
> cpu_map_generic_redirect(), so I think xdp_do_flush() is not needed for
> redirected skbs.
Now that I checked the down streams of cpu_map_bpf_prog_run_skb() it
does not queue anything to the per-CPU lists like I assumed. You are
right, it is no needed.
Sorry for the confusion.
> > rcu_read_unlock_bh(); /* resched point, may call do_softirq() */
> >
> > return nframes;
>
Sebastian
prev parent reply other threads:[~2023-09-11 6:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-08 13:57 [PATCH net 0/4] Add missing xdp_do_flush() invocations Sebastian Andrzej Siewior
2023-09-08 13:57 ` [PATCH net 1/4] net: ena: Flush XDP packets on error Sebastian Andrzej Siewior
2023-09-10 7:42 ` Kiyanovski, Arthur
2023-09-08 13:57 ` [PATCH net 2/4] bnxt_en: Flush XDP for bnxt_poll_nitroa0()'s NAPI Sebastian Andrzej Siewior
2023-09-08 16:30 ` Pavan Chebbi
2023-09-08 17:57 ` Michael Chan
2023-09-08 18:18 ` Andy Gospodarek
2023-09-08 13:57 ` [PATCH net 3/4] octeontx2-pf: Do xdp_do_flush() after redirects Sebastian Andrzej Siewior
2023-09-13 4:34 ` [EXT] " Geethasowjanya Akula
2023-09-08 13:57 ` [PATCH net 4/4] bpf, cpumap: Flush xdp after cpu_map_bpf_prog_run_skb() Sebastian Andrzej Siewior
2023-09-09 2:49 ` Hou Tao
2023-09-11 6:50 ` Sebastian Andrzej Siewior [this message]
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