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From: Kuniyuki Iwashima <kuniyu@google.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	 Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	 Eduard Zingerman <eddyz87@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	 Stanislav Fomichev <sdf@fomichev.me>,
	Eric Dumazet <edumazet@google.com>,
	 Neal Cardwell <ncardwell@google.com>,
	Willem de Bruijn <willemb@google.com>,
	 Tenzin Ukyab <ukyab@berkeley.edu>,
	Kuniyuki Iwashima <kuniyu@google.com>,
	 Kuniyuki Iwashima <kuni1840@gmail.com>,
	bpf@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH v2 bpf-next 07/11] bpf: mptcp: Don't support BPF_SOCK_OPS_RCVQ_CB.
Date: Fri, 22 May 2026 07:44:58 +0000	[thread overview]
Message-ID: <20260522074601.1658705-8-kuniyu@google.com> (raw)
In-Reply-To: <20260522074601.1658705-1-kuniyu@google.com>

MPTCP has its own sock->ops->set_rcvlowat() / mptcp_set_rcvlowat().

We should not allow calling __tcp_set_rcvlowat() for MPTCP subflows.

Let's disable BPF_SOCK_OPS_RCVQ_CB for MPTCP for now.

If needed in the future, bpf_sock_ops_tcp_set_rcvlowat() could be
extended to properly support MPTCP.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 net/core/filter.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index ff7fd415486a..5913b3be9f1d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5392,6 +5392,9 @@ static int bpf_sock_ops_check_rcvq_cb(struct sock *sk, int val)
 #endif
 		if (not_tcp_prot)
 			return -EBUSY;
+
+		if (unlikely(sk_is_mptcp(sk)))
+			return -EOPNOTSUPP;
 	}
 
 	return 0;
-- 
2.54.0.746.g67dd491aae-goog


  parent reply	other threads:[~2026-05-22  7:46 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-22  7:44 [PATCH v2 bpf-next 00/11] bpf: Add SOCK_OPS hooks for TCP AutoLOWAT Kuniyuki Iwashima
2026-05-22  7:44 ` [PATCH v2 bpf-next 01/11] selftest: bpf: Use BPF_SOCK_OPS_ALL_CB_FLAGS + 1 for bad_cb_test_rv Kuniyuki Iwashima
2026-05-22  8:22   ` bot+bpf-ci
2026-05-22  7:44 ` [PATCH v2 bpf-next 02/11] bpf: tcp: Introduce BPF_SOCK_OPS_RCVQ_CB Kuniyuki Iwashima
2026-05-22  8:22   ` bot+bpf-ci
2026-05-22  7:44 ` [PATCH v2 bpf-next 03/11] bpf: tcp: Support bpf_skb_load_bytes() for BPF_SOCK_OPS_RCVQ_CB Kuniyuki Iwashima
2026-05-22  7:44 ` [PATCH v2 bpf-next 04/11] tcp: Split out __tcp_set_rcvlowat() Kuniyuki Iwashima
2026-05-22  7:44 ` [PATCH v2 bpf-next 05/11] bpf: tcp: Add kfunc to adjust sk->sk_rcvlowat Kuniyuki Iwashima
2026-05-22  8:22   ` bot+bpf-ci
2026-05-22  7:44 ` [PATCH v2 bpf-next 06/11] bpf: tcp: Make BPF_SOCK_OPS_RCVQ_CB and SOCKMAP mutually exclusive Kuniyuki Iwashima
2026-05-22  7:44 ` Kuniyuki Iwashima [this message]
2026-05-22  7:44 ` [PATCH v2 bpf-next 08/11] bpf: tcp: Reject BPF_SOCK_OPS_RCVQ_CB if receive queue is not empty Kuniyuki Iwashima
2026-05-22  7:45 ` [PATCH v2 bpf-next 09/11] bpf: tcp: Factorise bpf_skops_established() Kuniyuki Iwashima
2026-05-22  7:45 ` [PATCH v2 bpf-next 10/11] bpf: tcp: Add SOCK_OPS rcvlowat hook Kuniyuki Iwashima
2026-05-22  7:45 ` [PATCH v2 bpf-next 11/11] selftest: bpf: Add test for BPF_SOCK_OPS_RCVQ_CB Kuniyuki Iwashima

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