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From: Jason Wang <jasowang@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Tanner Love <tannerlove.kernel@gmail.com>,
	Network Development <netdev@vger.kernel.org>,
	David Miller <davem@davemloft.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Petar Penkov <ppenkov@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Tanner Love <tannerlove@google.com>
Subject: Re: [PATCH net-next v4 2/3] virtio_net: add optional flow dissection in virtio_net_hdr_to_skb
Date: Thu, 10 Jun 2021 12:13:46 +0800	[thread overview]
Message-ID: <6ae4f189-a3be-075d-167c-2ad3f8d7d975@redhat.com> (raw)
In-Reply-To: <CAADnVQKHpk5aXA-MiuHyvBC7ZCxDPmN_gKAVww8kQAjoZkkmjA@mail.gmail.com>


在 2021/6/10 下午12:05, Alexei Starovoitov 写道:
> On Wed, Jun 9, 2021 at 8:53 PM Jason Wang <jasowang@redhat.com> wrote:
>>
>> It works but it couples virtio with bpf.
> Jason,
>
> I think your main concern is that it makes virtio_net_hdr into uapi?


Actually not. Note that, vnet header is already a part of uAPI 
(include/uapi/linux/virtio_net.h).

The concern is that is may confuse the userspace since we will have two 
sets of vnet header uapi (and they are already out of sync).


> That's not the case. __sk_buff is uapi, but pointers to sockets
> and other kernel data structures are not.
> Yes. It's a bit weird that uapi struct has a pointer to kernel internal,
> but I don't see it as a deal breaker.


Yes, but looking at the existing fields of __sk_buff. All are pretty 
generic fields that are device agnostic. This patch breaks this.


> Tracing progs have plenty of such cases.
> In networking there is tcp-bpf where everything is kernel internal and non-uapi.
> So after this patch virtio_net_hdr is free to change without worrying about bpf
> progs reading it.


So I wonder why not simply use helpers to access the vnet header like 
how tcp-bpf access the tcp header?

Thanks


  reply	other threads:[~2021-06-10  4:14 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08 17:02 [PATCH net-next v4 0/3] virtio_net: add optional flow dissection in virtio_net_hdr_to_skb Tanner Love
2021-06-08 17:02 ` [PATCH net-next v4 1/3] net: flow_dissector: extend bpf flow dissector support with vnet hdr Tanner Love
2021-06-08 22:08   ` Martin KaFai Lau
     [not found]     ` <CAOckAf8W04ynA4iXXzBe8kB_yauH9TKEJ_o6tt9tQuTJBx-G6A@mail.gmail.com>
2021-06-09 18:24       ` Martin KaFai Lau
2021-06-08 17:02 ` [PATCH net-next v4 2/3] virtio_net: add optional flow dissection in virtio_net_hdr_to_skb Tanner Love
2021-06-10  3:09   ` Jason Wang
2021-06-10  3:15     ` Willem de Bruijn
2021-06-10  3:53       ` Jason Wang
2021-06-10  4:05         ` Alexei Starovoitov
2021-06-10  4:13           ` Jason Wang [this message]
2021-06-10  4:19             ` Alexei Starovoitov
2021-06-10  5:23               ` Jason Wang
2021-06-10 14:04                 ` Willem de Bruijn
2021-06-11  2:10                   ` Jason Wang
2021-06-11  2:45                     ` Willem de Bruijn
2021-06-11  3:38                       ` Jason Wang
2021-06-11 14:12                         ` Willem de Bruijn
2021-06-14 20:41                           ` Tanner Love
2021-06-15  8:57                             ` Jason Wang
2021-06-15  8:55                           ` Jason Wang
2021-06-15 14:47                             ` Willem de Bruijn
2021-06-16 10:21                               ` Jason Wang
2021-06-17 14:43                                 ` Willem de Bruijn
2021-06-21  6:33                                   ` Jason Wang
2021-06-21 13:18                                     ` Willem de Bruijn
2021-06-22  2:37                                       ` Jason Wang
2021-06-08 17:02 ` [PATCH net-next v4 3/3] selftests/net: amend bpf flow dissector prog to do vnet hdr validation Tanner Love

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