From: Laurent Vivier <lvivier@redhat.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: passt-dev@passt.top
Subject: Re: [PATCH v8 7/8] vhost-user: add vhost-user
Date: Wed, 16 Oct 2024 12:07:21 +0200 [thread overview]
Message-ID: <45e1f806-7516-41df-a11f-028516bfd513@redhat.com> (raw)
In-Reply-To: <Zw3gHwUiVhTqvFZk@zatzit.fritz.box>
On 15/10/2024 05:23, David Gibson wrote:
>> +/**
>> + * tcp_vu_update_check() - Calculate TCP checksum
>> + * @tapside: Address information for one side of the flow
>> + * @iov: Pointer to the array of IO vectors
>> + * @iov_used: Length of the array
>> + */
>> +static void tcp_vu_update_check(const struct flowside *tapside,
>> + struct iovec *iov, int iov_used)
> AFAICT this is only used for the pcap path. Rather than filling in
> the checksum at a different point from normal, I think it would be
> easier to just clear the no_tcp_csum flag when pcap is enabled. That
> would, AFAICT, remove the need for this function entirely.
To do that is a little bit complicated because we need to pass the iov array to
tcp_fill_headers4()/tcp_fill_headers6() to be able to compute the checksum of the TCP part.
In tcp_buf, the TCP header and TCP payload are in the same iovec but with tcp_vu they can
be split on several iovecs. And if we provide the iovec , theoretically we should not
provide the TAP, IP and TCP headers via the parameters as they are in the iovec, but for
tcp_buf they have one iovec each, and with tcp_vu they are probably all in the same iovec
(the first one). So, again, it can be complicated to extract headers to update them.
In conclusion, I update the checksum only for VU and in the case of pcap because it is
simpler (the same logic applies for udp_update_hdr4()/udp_update_hdr6()).
I'm open to any suggestion that could do the checksum in
udp_update_hdr4()/udp_update_hdr6() (I agree with you, it should be the place to do it)
but I don't see an easy and nice way to implement it.
Thanks,
Laurent
next prev parent reply other threads:[~2024-10-16 10:07 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-10 12:28 [PATCH v8 0/8] Add vhost-user support to passt. (part 3) Laurent Vivier
2024-10-10 12:28 ` [PATCH v8 1/8] packet: replace struct desc by struct iovec Laurent Vivier
2024-10-10 12:28 ` [PATCH v8 2/8] vhost-user: introduce virtio API Laurent Vivier
2024-10-10 12:28 ` [PATCH v8 3/8] vhost-user: introduce vhost-user API Laurent Vivier
2024-10-10 12:28 ` [PATCH v8 4/8] udp: Prepare udp.c to be shared with vhost-user Laurent Vivier
2024-10-14 4:29 ` David Gibson
2024-10-10 12:28 ` [PATCH v8 5/8] tcp: Export headers functions Laurent Vivier
2024-10-14 4:29 ` David Gibson
2024-10-10 12:29 ` [PATCH v8 6/8] passt: rename tap_sock_init() to tap_backend_init() Laurent Vivier
2024-10-14 4:30 ` David Gibson
2024-10-14 22:38 ` Stefano Brivio
2024-10-10 12:29 ` [PATCH v8 7/8] vhost-user: add vhost-user Laurent Vivier
2024-10-15 3:23 ` David Gibson
2024-10-16 10:07 ` Laurent Vivier [this message]
2024-10-16 16:26 ` Stefano Brivio
2024-10-15 19:54 ` Stefano Brivio
2024-10-16 0:41 ` David Gibson
2024-10-17 0:10 ` Stefano Brivio
2024-10-17 11:25 ` Stefano Brivio
2024-10-17 11:54 ` Laurent Vivier
2024-10-17 17:18 ` Laurent Vivier
2024-10-17 17:25 ` Laurent Vivier
2024-10-17 17:33 ` Stefano Brivio
2024-10-17 21:21 ` Stefano Brivio
2024-10-22 12:59 ` Laurent Vivier
2024-10-22 13:19 ` Stefano Brivio
2024-10-22 18:19 ` Stefano Brivio
2024-10-22 18:22 ` Stefano Brivio
2024-10-23 15:27 ` Laurent Vivier
2024-10-23 16:23 ` Stefano Brivio
2024-10-17 0:10 ` Stefano Brivio
2024-10-17 7:28 ` Laurent Vivier
2024-10-17 8:33 ` Stefano Brivio
2024-11-14 10:20 ` Laurent Vivier
2024-11-14 14:23 ` Stefano Brivio
2024-11-14 15:16 ` Laurent Vivier
2024-11-14 15:38 ` Stefano Brivio
2024-11-14 10:23 ` Laurent Vivier
2024-11-14 14:23 ` Stefano Brivio
2024-11-15 8:30 ` Laurent Vivier
2024-11-15 10:08 ` Stefano Brivio
2024-11-14 10:29 ` Laurent Vivier
2024-11-14 14:23 ` Stefano Brivio
2024-11-15 11:13 ` Laurent Vivier
2024-11-15 11:23 ` Stefano Brivio
2024-10-10 12:29 ` [PATCH v8 8/8] test: Add tests for passt in vhost-user mode Laurent Vivier
2024-10-15 3:40 ` David Gibson
2024-10-15 19:54 ` Stefano Brivio
2024-10-16 8:06 ` Laurent Vivier
2024-10-16 9:47 ` Stefano Brivio
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=45e1f806-7516-41df-a11f-028516bfd513@redhat.com \
--to=lvivier@redhat.com \
--cc=david@gibson.dropbear.id.au \
--cc=passt-dev@passt.top \
/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.
Code repositories for project(s) associated with this public inbox
https://passt.top/passt
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 IMAP folder(s).