netdev - Re: [PATCH bpf-next v3 0/5] sockmap: Fix reading with splice(2)

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Message-ID: <20250711155727.qjg2zc6r46h5wof2@gmail.com>
Date: Fri, 11 Jul 2025 08:57:27 -0700
From: John Fastabend <john.fastabend@...il.com>
To: vincent.whitchurch@...adoghq.com
Cc: Jakub Sitnicki <jakub@...udflare.com>,
	Kuniyuki Iwashima <kuniyu@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next v3 0/5] sockmap: Fix reading with splice(2)

On 2025-07-09 14:47:56, Vincent Whitchurch via B4 Relay wrote:
> I noticed that if the verdict callback returns SK_PASS, using splice(2)
> to read from a socket in a sockmap does not work since it never sees the
> data queued on to it.  As far as I can see, this is not a regression but
> just something that has never worked, but it does make sockmap unusable
> if you can't guarantee that the programs using the socket will not use
> splice(2).

Correct it was never supported.

> 
> This series attempts to fix it and add a test for it.

Thanks I had this todo on my list, but never got to it.

> 
> ---
> Changes in v3:
> - Rebase on latest bpf-next/master
> - Link to v2: https://lore.kernel.org/r/20250609-sockmap-splice-v2-0-9c50645cfa32@datadoghq.com
> 
> Changes in v2:
> - Rebase on latest bpf-next/master
> - Remove unnecessary change in inet_dgram_ops
> - Remove ->splice_read NULL check in inet_splice_read()
> - Use INDIRECT_CALL_1() in inet_splice_read()
> - Include test case in default test suite in test_sockmap
> - Link to v1: https://lore.kernel.org/r/20240606-sockmap-splice-v1-0-4820a2ab14b5@datadoghq.com
> 
> ---
> Vincent Whitchurch (5):
>       net: Add splice_read to prot
>       tcp_bpf: Fix reading with splice(2)
>       selftests/bpf: sockmap: Exit with error on failure
>       selftests/bpf: sockmap: Allow SK_PASS in verdict
>       selftests/bpf: sockmap: Add splice + SK_PASS regression test
> 
>  include/net/inet_common.h                  |  3 +
>  include/net/sock.h                         |  3 +
>  net/ipv4/af_inet.c                         | 13 ++++-
>  net/ipv4/tcp_bpf.c                         |  9 +++
>  net/ipv4/tcp_ipv4.c                        |  1 +
>  net/ipv6/af_inet6.c                        |  2 +-
>  net/ipv6/tcp_ipv6.c                        |  1 +
>  tools/testing/selftests/bpf/test_sockmap.c | 90 +++++++++++++++++++++++++++++-
>  8 files changed, 118 insertions(+), 4 deletions(-)
> ---
> base-commit: ad97cb2ed06a6ba9025fd8bd14fa24369550cbb5
> change-id: 20240606-sockmap-splice-d371ac07d7b4
> 
> Best regards,
> -- 
> Vincent Whitchurch <vincent.whitchurch@...adoghq.com>
> 
>