From: Bobby Eshleman <bobbyeshleman@gmail.com>
To: Stefano Garzarella <sgarzare@redhat.com>
Cc: Arseniy Krasnov <avkrasnov@sberdevices.ru>,
Bobby Eshleman <bobby.eshleman@bytedance.com>,
kvm@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, oxffffaa@gmail.com,
Eric Dumazet <edumazet@google.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
kernel@sberdevices.ru, Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [RFC PATCH v2 2/4] virtio/vsock: remove all data from sk_buff
Date: Tue, 7 Mar 2023 23:53:17 +0000 [thread overview]
Message-ID: <ZAfObcosX5PlS4Lf@bullseye> (raw)
In-Reply-To: <20230306161852.4s7qf4qm3fnwjck7@sgarzare-redhat>
On Mon, Mar 06, 2023 at 05:18:52PM +0100, Stefano Garzarella wrote:
> On Mon, Mar 06, 2023 at 07:00:10PM +0300, Arseniy Krasnov wrote:
> >
> >
> > On 06.03.2023 18:51, Stefano Garzarella wrote:
> > > On Mon, Mar 06, 2023 at 06:31:22PM +0300, Arseniy Krasnov wrote:
> > > >
> > > >
> > > > On 06.03.2023 15:08, Stefano Garzarella wrote:
> > > > > On Sun, Mar 05, 2023 at 11:07:37PM +0300, Arseniy Krasnov wrote:
> > > > > > In case of SOCK_SEQPACKET all sk_buffs are used once - after read some
> > > > > > data from it, it will be removed, so user will never read rest of the
> > > > > > data. Thus we need to update credit parameters of the socket like whole
> > > > > > sk_buff is read - so call 'skb_pull()' for the whole buffer.
> > > > > >
> > > > > > Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
> > > > > > Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
> > > > > > ---
> > > > > > net/vmw_vsock/virtio_transport_common.c | 2 +-
> > > > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > > >
> > > > > Maybe we could avoid this patch if we directly use pkt_len as I
> > > > > suggested in the previous patch.
> > > > Hm, may be we can avoid calling 'skb_pull()' here if 'virtio_transport_dec_rx_pkt()'
> > > > will use integer argument?
> > >
> > > Yep, exactly!
> > >
> > > > Just call 'virtio_transport_dec_rx_pkt(skb->len)'. skb
> > >
> > > It depends on how we call virtio_transport_inc_rx_pkt(). If we use
> > > hdr->len there I would use the same to avoid confusion. Plus that's the
> > > value the other peer sent us, so definitely the right value to increase
> > > fwd_cnt with. But if skb->len always reflects it, then that's fine.
> > i've checked 'virtio_transport_rx_work()', it calls 'virtio_vsock_skb_rx_put()' which
> > sets 'skb->len'. Value is used from header, so seems 'skb->len' == 'hdr->len' in this
> > case.
>
> Thank you for checking it.
>
> However, I still think it is better to use `hdr->len` (we have to assign it
> to `pkt_len` anyway, as in the proposal I sent for patch 1), otherwise we
> have to go every time to check if skb_* functions touch skb->len.
>
> E.g. skb_pull() decrease skb->len, so I'm not sure we can call
> virtio_transport_dec_rx_pkt(skb->len) if we don't remove `skb_pull(skb,
> bytes_to_copy);` inside the loop.
>
I think it does make reasoning about the bytes accounting easier if it
is based off of the non-mutating hdr->len.
Especially if vsock does ever support tunneling (e.g., through
virtio-net) or some future feature that makes the skb->len more dynamic.
Best,
Bobby
next prev parent reply other threads:[~2023-03-08 0:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-05 20:04 [RFC PATCH v2 0/4] virtio/vsock: fix credit update logic Arseniy Krasnov
2023-03-05 20:06 ` [RFC PATCH v2 1/4] virtio/vsock: fix 'rx_bytes'/'fwd_cnt' calculation Arseniy Krasnov
2023-03-06 11:57 ` Stefano Garzarella
2023-03-06 15:27 ` Arseniy Krasnov
2023-03-05 20:07 ` [RFC PATCH v2 2/4] virtio/vsock: remove all data from sk_buff Arseniy Krasnov
2023-03-06 12:08 ` Stefano Garzarella
2023-03-06 15:31 ` Arseniy Krasnov
2023-03-06 15:51 ` Stefano Garzarella
2023-03-06 16:00 ` Arseniy Krasnov
2023-03-06 16:18 ` Stefano Garzarella
2023-03-07 23:53 ` Bobby Eshleman [this message]
2023-03-05 20:08 ` [RFC PATCH v2 3/4] virtio/vsock: free skb on data copy failure Arseniy Krasnov
2023-03-06 12:07 ` Stefano Garzarella
2023-03-06 15:28 ` Arseniy Krasnov
2023-03-05 20:09 ` [RFC PATCH v2 4/4] test/vsock: invalid buffer tests Arseniy Krasnov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZAfObcosX5PlS4Lf@bullseye \
--to=bobbyeshleman@gmail.com \
--cc=avkrasnov@sberdevices.ru \
--cc=bobby.eshleman@bytedance.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=kernel@sberdevices.ru \
--cc=kuba@kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=oxffffaa@gmail.com \
--cc=pabeni@redhat.com \
--cc=sgarzare@redhat.com \
--cc=stefanha@redhat.com \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).