From nobody Fri Oct 18 08:50:47 2024 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9EAFB137757; Thu, 18 Jul 2024 10:34:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721298864; cv=none; b=d4EhzbGasFAAYKGmLtHWiFn+ASTNcTtgguPi0gnjiz59SeVNzf6vKcB+NEMxFhyKEc5gr5n7BaFDVaphDCtmmqUb7a0eIIPgKDVg9RLx3TnaqLObn1FeAAelK+czLHVi17vfXjGeHYr0Nm+YJAeFb/mk1JoZQx3V4YaS6eZDpBc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721298864; c=relaxed/simple; bh=v7Pr56rb4xW7zvxZmarCh7nw1f560R1oMhklrIazOeo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=h4ILnWQcUQ1PfP07yQjG2yX4BsluX+eHA7etSmDSyZRxyIzjyAk63pnO0cmvXhFUThk0nk9rn8CElbVROYjQ7nuEbNqtj/3zATGs9JQVOaK7TSvYnIa0qni2X+MW9DenvrRkEj2g11AJWTwXqD+2+AobDzV2ricQW21OsAq9c9o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sKqDCuj7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sKqDCuj7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CE7FC4AF0B; Thu, 18 Jul 2024 10:34:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721298864; bh=v7Pr56rb4xW7zvxZmarCh7nw1f560R1oMhklrIazOeo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=sKqDCuj7vairxNbQPltODvUeuzLbGkak3VzLKCjEmH+38l/yuYGwkZbJrGgeo5Wff wh72k2oEze/hVvbdO0BCrj/N9dKAew0GojI+Lfc8o+PlAt6DIuYLXuIqjR5VyPiW7+ LqpJ4/EO/3e/sw+H50FsuCAFPaUib7LGe4qyIWOygb++nd2c9XbhA8GLduzROWbJZl lsBBbJlar9WHdntLMdf3RVbgNy8S2w80oPnmiQgDvBbLJ1n4MoZeDvrGVH3VpBNC4V LK2C/AdoUUqcCXFJ9p0rVKwnGOpzLHJJGiPdemTsI24+DtsTfdiBrDLDIryebdb+5B GY2Yf70N0db7A== From: "Matthieu Baerts (NGI0)" Date: Thu, 18 Jul 2024 12:33:57 +0200 Subject: [PATCH net v2 2/2] tcp: limit wake-up for crossed SYN cases to SYN-ACK Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20240718-upstream-net-next-20240716-tcp-3rd-ack-consume-sk_socket-v2-2-d653f85639f6@kernel.org> References: <20240718-upstream-net-next-20240716-tcp-3rd-ack-consume-sk_socket-v2-0-d653f85639f6@kernel.org> In-Reply-To: <20240718-upstream-net-next-20240716-tcp-3rd-ack-consume-sk_socket-v2-0-d653f85639f6@kernel.org> To: Eric Dumazet , "David S. Miller" , David Ahern , Jakub Kicinski , Paolo Abeni , Kuniyuki Iwashima , Jerry Chu Cc: netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" X-Mailer: b4 0.14.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2053; i=matttbe@kernel.org; h=from:subject:message-id; bh=v7Pr56rb4xW7zvxZmarCh7nw1f560R1oMhklrIazOeo=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBmmO+oidQcOp7WgYYSyX0/O0xhsCh4ZAUIQ/Csp VR244lKzdiJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZpjvqAAKCRD2t4JPQmmg c7YpEACM79BFPN8vnPh61+T9XVJery417L0PZFZC76xymxb86ifiBMSdUFX3DRbWimOqNVLNnJA i1cWVRtdRUn1BU+0YVLcBtbnmY1CIPFBoLEIhiSMW2e8dqg/Uyux7moGMqzDS5nGb6CYknxr/ev hhzNbfiVAwk6vgSON563xkDnd+MfBe7Ywny8IOOPECyHm66flOOZU3QQ6WoZIGkKztVMNNdnCrU nmLZH0+/BPUi1QcZAl7jOOhJYklJLOmXMguctdumWbDIiqoEK98mjGR1HIIFgEO8PGocWxTKfGd ko7s+jryLrZzfadLCn14hpMPKcwvgGoe335ylaCNHs+EljLu0UQDj3R5bmJhURnUlrT7YkFLOJ6 BGBdTqIMrpwLOrjZfBhgGO+pCa0/KCY6gwP3OOtuTQUdz+zGYPcoRuFIe59GyWlD9kFYv072VdB B692ywT6+dxFxvz+jjKD5409VHapq8iiaju9W56FZyY9goqZR1beuQRt0c/2+X9ib78MrcT6rEd 0QMpPFHMrelqg6mBNHWJBbFjG8uxQfPnAve329yXPtnxHCQSw0B7qR4/xTqt7WHHGX8USO4kjDu o/5uW02imOuLrc2M0SUU7tw/aYf9BVGiZI/sO5lRRxwukUc8LnBVuzjLqSD8z/Fp7mBnHgHdaYM /pO8Na/XLPBvYCg== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 sk->sk_socket will be assigned in case of marginal crossed SYN, but also in other cases, e.g. - With TCP Fast Open, if the connection got accept()'ed before receiving the 3rd ACK ; - With MPTCP, when accepting additional subflows to an existing MPTCP connection. In these cases, the switch to TCP_ESTABLISHED is done when receiving the 3rd ACK, without the SYN flag then. To properly restrict the wake-up to crossed SYN cases, it is then required to also limit the check to packets containing the SYN-ACK flags. While at it, also update the attached comment: sk->sk_sleep has been removed in 2010, and replaced by sk->sk_wq in commit 43815482370c ("net: sock_def_readable() and friends RCU conversion"). Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path") Suggested-by: Kuniyuki Iwashima Signed-off-by: Matthieu Baerts (NGI0) --- Notes: - The above 'Fixes' tag should correspond to the commit introducing the possibility to have sk->sk_socket being set there in other cases than the crossed SYN one. But I might have missed other cases. Maybe 1da177e4c3f4 ("Linux-2.6.12-rc2") might be safer? On the other hand, I don't think this wake-up was causing any visible issue, apart from not being needed. --- net/ipv4/tcp_input.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index bfe1bc69dc3e..5cebb389bf71 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6797,9 +6797,9 @@ tcp_rcv_state_process(struct sock *sk, struct sk_buff= *skb) =20 /* Note, that this wakeup is only for marginal crossed SYN case. * Passively open sockets are not waked up, because - * sk->sk_sleep =3D=3D NULL and sk->sk_socket =3D=3D NULL. + * sk->sk_wq =3D=3D NULL and sk->sk_socket =3D=3D NULL. */ - if (sk->sk_socket) + if (sk->sk_socket && th->syn) sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); =20 tp->snd_una =3D TCP_SKB_CB(skb)->ack_seq; --=20 2.45.2