From: Stefano Brivio <sbrivio@redhat.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: Laurent Vivier <lvivier@redhat.com>, passt-dev@passt.top
Subject: Re: [PATCH 1/7] tcp: Pass TCP header and payload separately to tcp_update_check_tcp[46]()
Date: Mon, 28 Oct 2024 19:42:54 +0100 [thread overview]
Message-ID: <20241028194254.71df8d2f@elisabeth> (raw)
In-Reply-To: <20241028094050.1609090-2-david@gibson.dropbear.id.au>
On Mon, 28 Oct 2024 20:40:44 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:
> Currently these expects both the TCP header and payload in a single IOV,
> and goes to some trouble to locate the checksum field within it. In the
> current caller we've already know where the TCP header is, so we might as
> well just pass it in. This will need to work a bit differently for
> vhost-user, but that code already needs to locate the TCP header for other
> reasons, so again we can just pass it in.
We couldn't do this, and also what you're now doing in 5/7, because
with vhost-user the TCP header is not aligned, so we can't pass it
around as a pointer, see:
<ZeUpxEY-sn64NLE5@zatzit>
https://archives.passt.top/passt-dev/ZeUpxEY-sn64NLE5@zatzit/
and following. That one is about IP headers, but the same applies to
TCP and UDP headers.
Of course the current solution is not elegant and it would be nice to
find another way to deal with it, but we couldn't come up with anything
better back then.
The rest of the series looks good to me, but I'm afraid that without
this one and 5/7 the other changes will be a bit more complicated to
implement (if at all possible).
--
Stefano
next prev parent reply other threads:[~2024-10-28 18:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-28 9:40 [PATCH 0/7] Rework some IOV handling in TCP code David Gibson
2024-10-28 9:40 ` [PATCH 1/7] tcp: Pass TCP header and payload separately to tcp_update_check_tcp[46]() David Gibson
2024-10-28 18:42 ` Stefano Brivio [this message]
2024-10-29 3:02 ` David Gibson
2024-10-29 4:07 ` David Gibson
2024-10-29 9:09 ` Stefano Brivio
2024-10-29 9:26 ` David Gibson
2024-10-29 10:32 ` Stefano Brivio
2024-10-28 9:40 ` [PATCH 2/7] tcp: Move tcp_l2_buf_fill_headers() to tcp_buf.c David Gibson
2024-10-28 9:40 ` [PATCH 3/7] tcp: Rework tcp_l2_buf_fill_headers() into tcp_buf_make_frame() David Gibson
2024-10-28 9:40 ` [PATCH 4/7] tcp: Don't use return value from tcp_fill_headers[46] to adjust iov_len David Gibson
2024-10-28 9:40 ` [PATCH 5/7] tcp: Pass TCP header and payload separately to tcp_fill_headers[46]() David Gibson
2024-10-28 9:40 ` [PATCH 6/7] tcp: Merge tcp_update_check_tcp[46]() David Gibson
2024-10-28 9:40 ` [PATCH 7/7] tcp: Fold tcp_update_csum() into tcp_fill_header() David Gibson
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