From nobody Sun Feb 8 23:06:10 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 402F41E832A for ; Sat, 5 Jul 2025 07:25:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751700306; cv=none; b=PGbj1XSZ+0t2iDA0fwYvhdeTUoVhH1VN7lnWYnprrt/18A+ffOSjlAdRw13W8VoKt8xlppWwT32wkOjU1i8lZJeOMAffA9GsovF+o5pZSZ5FwGIoxeuPrhf1m/gBdHaU68dDv5I0L2yuyHqcHtbNQyVwuqgmYZQ2eIQFkqPKtsI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751700306; c=relaxed/simple; bh=3UdE8nDz3yKO0TcLJyjWu5fI513RkG85kFPLaJGW6xk=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=NB3leAuRQUnzRxH92ZBmXnpu4JoEykm57DEi/hCcHQNkpBvHXXXagh7tODYmlVi3bZHasrzgz4szdU0ZmLUsjar5IMepkTTgMiPvWH6QUXr/EYjEM4yci36DA85TSQTgckW6BL6s+Wz0XlT9Hi8qcl5d1Yx1523rQZFaPzmFdls= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OQ037hXM; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OQ037hXM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1751700304; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M/UJZt6eXZ3rLt6LaHP+FnToEe+9sEyt3IfRaOO1lgw=; b=OQ037hXMDhpBlOAAIKKP8V9CPvd23em8GkHHdFSFBxGGMpIjmbsdyVgYOGZS1jbK6Nr3Hx Y0ZAUTi6V8ijyG/UTVhgK6S1fFiho+ABqRzp52NeMJfavoPkUXzycGWStTZKbQdlnk99Vg 8uPQ30hzfl62f/CxVHxNbitoC+mkUpo= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-517-aWxjGGHSMVqPe_8owPiVnA-1; Sat, 05 Jul 2025 03:25:02 -0400 X-MC-Unique: aWxjGGHSMVqPe_8owPiVnA-1 X-Mimecast-MFC-AGG-ID: aWxjGGHSMVqPe_8owPiVnA_1751700301 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 24A9E1944A82 for ; Sat, 5 Jul 2025 07:25:01 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.224.15]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 1961B195608F for ; Sat, 5 Jul 2025 07:24:59 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-net v2 3/5] mptcp: fix status reset on disconnect() Date: Sat, 5 Jul 2025 09:24:47 +0200 Message-ID: In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: DzUb2iOHgC9Ub4FONNuWDQUm-t6Leu-Ghc3q8Ou-gHc_1751700301 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" disconnect() can still race with subflow fallback leaving the msk in inconsistent status. To avoid such race, disconnect() must be blocking, error out if the argument prevent such wait: the socket will linger in SS_DISCONNECT state forever. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 71b258aebcd9..0dc55a17f274 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3119,8 +3119,19 @@ static void mptcp_copy_inaddrs(struct sock *msk, con= st struct sock *ssk) inet_sk(msk)->inet_rcv_saddr =3D inet_sk(ssk)->inet_rcv_saddr; } =20 +/* can safely clear the fallback status only if no subflow is going to + * push or receive any data on the wire + */ +static bool mptcp_can_reset_fb_status(const struct mptcp_sock *msk) +{ + return list_empty(&msk->conn_list) || + inet_sk_state_load(msk->first) =3D=3D TCP_CLOSE; +} + static int mptcp_disconnect(struct sock *sk, int flags) { + long timeout =3D sock_sndtimeo(sk, flags & MSG_DONTWAIT); + DEFINE_WAIT_FUNC(wait, woken_wake_function); struct mptcp_sock *msk =3D mptcp_sk(sk); =20 /* We are on the fastopen error path. We can't call straight into the @@ -3142,7 +3153,34 @@ static int mptcp_disconnect(struct sock *sk, int fla= gs) * subflow */ mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE); + + if (!mptcp_can_reset_fb_status(msk)) { + if (!timeout) + return -EAGAIN; + + add_wait_queue(sk_sleep(sk), &wait); + + /* __mptcp_close_ssk() will wake us */ + do { + if (sk_wait_event(sk, &timeout, + mptcp_can_reset_fb_status(msk), + &wait)) + break; + } while (!signal_pending(current) && timeout); + + remove_wait_queue(sk_sleep(sk), &wait); + + /* timeout/signal can prevent reaching the expected status */ + if (!mptcp_can_reset_fb_status(msk)) + return -EBUSY; + } + + spin_lock_bh(&msk->fallback_lock); + msk->allow_subflows =3D true; + msk->allow_infinite_fallback =3D true; WRITE_ONCE(msk->flags, 0); + spin_unlock_bh(&msk->fallback_lock); + msk->cb_flags =3D 0; msk->recovery =3D false; WRITE_ONCE(msk->can_ack, false); --=20 2.49.0