From: Arseniy Krasnov <avkrasnov@sberdevices.ru>
To: Stefan Hajnoczi <stefanha@redhat.com>,
Stefano Garzarella <sgarzare@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Bobby Eshleman <bobby.eshleman@bytedance.com>
Cc: <kvm@vger.kernel.org>,
<virtualization@lists.linux-foundation.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<kernel@sberdevices.ru>, <oxffffaa@gmail.com>,
<avkrasnov@sberdevices.ru>
Subject: [RFC PATCH v1 0/3] virtio/vsock: fix credit update logic
Date: Sat, 4 Mar 2023 00:57:48 +0300 [thread overview]
Message-ID: <c2d3e204-89d9-88e9-8a15-3fe027e56b4b@sberdevices.ru> (raw)
Hello,
this patchset fixes two things in credit account logic:
1) Current implementation of 'virtio_transport_dec_rx_pkt()':
value to update 'rx_bytes' and 'fwd_cnt' is calculated as:
skb_headroom(skb) - sizeof(struct virtio_vsock_hdr) - skb->len;
i'm a little bit confused about subtracting 'skb->len'. It is clear,
that difference between first two components is number of bytes copied
to user. 'skb_headroom()' is delta between 'data' and 'head'. 'data'
is incremented on each copy data to user from skb by call 'skb_pull()'
(at the same moment, 'skb->len' is decremented to the same amount of
bytes). 'head' points to the header of the packet. But what is purpose
of 'skb->len' here? For SOCK_STREAM is has no effect because this
logic is called only when 'skb->len' == 0, but for SOCK_SEQPACKET and
other future calls i think it is buggy.
2) For SOCK_SEQPACKET all sk_buffs are handled only once - after dequeue
each sk_buff is removed, so user will never read rest of the data.
Thus we need to update credit parameters of the socket ('rx_bytes' and
'fwd_cnt') like whole sk_buff is read - so call 'skb_pull()' for the
whole buffer.
Reproducer is included. To trigger problem run vsock_test without two
patches with fix - You will see 'Negative len:'. Patches with fixes
depends on reproducer due to 'pr_emerg()', but i can resend them, seems
not a big deal.
Arseniy Krasnov (3):
test/vsock: SOCK_SEQPACKET 'rx_bytes'/'fwd_cnt' bug reproducer
virtio/vsock: fix 'rx_bytes'/'fwd_cnt' calculation
virtio/vsock: remove all data from sk_buff
net/vmw_vsock/virtio_transport_common.c | 8 +++--
tools/testing/vsock/vsock_test.c | 44 +++++++++++++++++++++++++
2 files changed, 50 insertions(+), 2 deletions(-)
--
2.25.1
next reply other threads:[~2023-03-04 0:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-03 21:57 Arseniy Krasnov [this message]
2023-03-03 22:00 ` [RFC PATCH v1 1/3] test/vsock: SOCK_SEQPACKET 'rx_bytes'/'fwd_cnt' bug reproducer Arseniy Krasnov
2023-03-03 22:01 ` [RFC PATCH v1 2/3] virtio/vsock: fix 'rx_bytes'/'fwd_cnt' calculation Arseniy Krasnov
2023-03-03 22:02 ` [RFC PATCH v1 3/3] virtio/vsock: remove all data from sk_buff Arseniy Krasnov
[not found] ` <CALa-AnCu8g+jt1m_rY0QJFcRUhtWJ64Txro69j9KsnK7hyuBMg@mail.gmail.com>
2023-03-04 11:53 ` [External] " 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=c2d3e204-89d9-88e9-8a15-3fe027e56b4b@sberdevices.ru \
--to=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).