From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1F01C3DA7A for ; Thu, 5 Jan 2023 21:01:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235589AbjAEVBi (ORCPT ); Thu, 5 Jan 2023 16:01:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235599AbjAEVBb (ORCPT ); Thu, 5 Jan 2023 16:01:31 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 317A535933 for ; Thu, 5 Jan 2023 13:00:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1672952443; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=tzR1wuYK3UmrwZ+hCZQA6kbAzh2uxHYFM70DAhZqBlU=; b=JOZ5aTRGg4niU5T7/GnLhMQIZFPkt5Q/8gmE8vT9taDF0yoN8HnHAGiOmQCKGJs9qb0OXb ePf3iQqvCwGq4I4UIQ6O8EiFRavcr0larmFrkMLseCKxDpAtM2ox0m9/ZRr+LEOmtn2aYm I9iG83Jd7WK/yZptJN1Br6cXkc4GWEE= Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-103-jzudp9ikPL-iKemDCm3EHg-1; Thu, 05 Jan 2023 16:00:42 -0500 X-MC-Unique: jzudp9ikPL-iKemDCm3EHg-1 Received: by mail-pg1-f199.google.com with SMTP id k16-20020a635a50000000b0042986056df6so17383664pgm.2 for ; Thu, 05 Jan 2023 13:00:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=tzR1wuYK3UmrwZ+hCZQA6kbAzh2uxHYFM70DAhZqBlU=; b=6nq1r8mNn82p4WaJoR1+JxzEkGXNZTVd4Zco16rJKNyN/eXgPKbvo6G7Mw/tEkKmW3 YeYCu+nfRCRcXLie6W6BYeJT2tFtqE98RTqLuxtR8bnFSCvKG9OJDGlGoK/df1fAGOo/ MIRtsqYZSPXFI61R+DMNZJwby+27eSnPyl/tlYPPE0IOjgkvR+58aGUI+9iSyjSOc69K dfgTFSuI8hSCWMNMt8LzSp05tBSoJSfL+1YqJDgyFQi3INAhOfpWk6O5fRghUQgZ7EtY t92hKloEU2knXUGw2GxLTEvEMyI+NbtQDo2/CvIyuaaNpFLqTjfxwXIo7yeI+SqwdNP/ ZevA== X-Gm-Message-State: AFqh2koAaYojajHbBnFBYMdP3i6leTnzrjRwN+f93kaAf2mOcg9ZQJwg Mt9JwBMWPPPD8Ar6EKL7ZJMgB0NP3n9RCuU5r5ejkFzEucP98Y1CRTUGtjd0nYcGjU8MM8LvSpx m7anFgJi4lTDJXsMC X-Received: by 2002:a17:902:f604:b0:192:55ab:88fe with SMTP id n4-20020a170902f60400b0019255ab88femr59519109plg.56.1672952440604; Thu, 05 Jan 2023 13:00:40 -0800 (PST) X-Google-Smtp-Source: AMrXdXsStt8vIjhcmCC1xPxFgNuYCD+E2HWcvG2z9NLpGXZEusMwS+11yc/i6oZSoLkZhcemO6CG4A== X-Received: by 2002:a17:902:f604:b0:192:55ab:88fe with SMTP id n4-20020a170902f60400b0019255ab88femr59519092plg.56.1672952440362; Thu, 05 Jan 2023 13:00:40 -0800 (PST) Received: from kernel-devel ([240d:1a:c0d:9f00:ca6:1aff:fead:cef4]) by smtp.gmail.com with ESMTPSA id i9-20020a170902cf0900b0018999a3dd7esm26316946plg.28.2023.01.05.13.00.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Jan 2023 13:00:39 -0800 (PST) Date: Fri, 6 Jan 2023 06:00:35 +0900 From: Shigeru Yoshida To: Mat Martineau Cc: matthieu.baerts@tessares.net, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dmytro@shytyi.net, netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mptcp: Fix deadlock in mptcp_sendmsg() Message-ID: References: <20230105201205.1087439-1-syoshida@redhat.com> <548fc9cf-b674-f37e-8ff7-9abae0bf15a8@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <548fc9cf-b674-f37e-8ff7-9abae0bf15a8@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Jan 05, 2023 at 12:26:29PM -0800, Mat Martineau wrote: > On Fri, 6 Jan 2023, Shigeru Yoshida wrote: > > > __mptcp_close_ssk() can be called from mptcp_sendmsg() with subflow > > socket locked. This can cause a deadlock as below: > > > > mptcp_sendmsg() > > mptcp_sendmsg_fastopen() --> lock ssk > > tcp_sendmsg_fastopen() > > __inet_stream_connect() > > mptcp_disconnect() > > mptcp_destroy_common() > > __mptcp_close_ssk() --> lock ssk again > > > > This patch fixes the issue by skipping locking for subflow socket > > which is already locked. > > > > Hi Shigeru - > > I believe this has already been fixed by: > > 7d803344fdc3 ("mptcp: fix deadlock in fastopen error path") > > It is in the net repo: > > https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git Hi Mat, Thank you so much for your prompt response. I've missed above patch. Yes, the patch fixed the same issue. Thank you~ Shigeru > > ...but hasn't been merged to net-next or Linus' tree yet. Jakub said to > expect a net PR today, which should get the fix both upstream and in to > net-next. > > Thanks, > > Mat > > > Fixes: d98a82a6afc7 ("mptcp: handle defer connect in mptcp_sendmsg") > > Signed-off-by: Shigeru Yoshida > > --- > > net/mptcp/protocol.c | 15 +++++++++------ > > net/mptcp/protocol.h | 4 ++-- > > 2 files changed, 11 insertions(+), 8 deletions(-) > > > > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > > index f6f93957275b..979265f66082 100644 > > --- a/net/mptcp/protocol.c > > +++ b/net/mptcp/protocol.c > > @@ -1672,9 +1672,9 @@ static int mptcp_sendmsg_fastopen(struct sock *sk, struct sock *ssk, struct msgh > > lock_sock(ssk); > > msg->msg_flags |= MSG_DONTWAIT; > > msk->connect_flags = O_NONBLOCK; > > - msk->is_sendmsg = 1; > > + msk->sendmsg_locked_sk = ssk; > > ret = tcp_sendmsg_fastopen(ssk, msg, copied_syn, len, NULL); > > - msk->is_sendmsg = 0; > > + msk->sendmsg_locked_sk = NULL; > > msg->msg_flags = saved_flags; > > release_sock(ssk); > > > > @@ -2319,7 +2319,8 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, > > if (dispose_it) > > list_del(&subflow->node); > > > > - lock_sock_nested(ssk, SINGLE_DEPTH_NESTING); > > + if (msk->sendmsg_locked_sk != ssk) > > + lock_sock_nested(ssk, SINGLE_DEPTH_NESTING); > > > > if (flags & MPTCP_CF_FASTCLOSE) { > > /* be sure to force the tcp_disconnect() path, > > @@ -2335,7 +2336,8 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, > > tcp_disconnect(ssk, 0); > > msk->subflow->state = SS_UNCONNECTED; > > mptcp_subflow_ctx_reset(subflow); > > - release_sock(ssk); > > + if (msk->sendmsg_locked_sk != ssk) > > + release_sock(ssk); > > > > goto out; > > } > > @@ -2362,7 +2364,8 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, > > /* close acquired an extra ref */ > > __sock_put(ssk); > > } > > - release_sock(ssk); > > + if (msk->sendmsg_locked_sk != ssk) > > + release_sock(ssk); > > > > sock_put(ssk); > > > > @@ -3532,7 +3535,7 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) > > /* if reaching here via the fastopen/sendmsg path, the caller already > > * acquired the subflow socket lock, too. > > */ > > - if (msk->is_sendmsg) > > + if (msk->sendmsg_locked_sk) > > err = __inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags, 1); > > else > > err = inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags); > > diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h > > index 955fb3d88eb3..43afc399e16b 100644 > > --- a/net/mptcp/protocol.h > > +++ b/net/mptcp/protocol.h > > @@ -294,8 +294,7 @@ struct mptcp_sock { > > u8 mpc_endpoint_id; > > u8 recvmsg_inq:1, > > cork:1, > > - nodelay:1, > > - is_sendmsg:1; > > + nodelay:1; > > int connect_flags; > > struct work_struct work; > > struct sk_buff *ooo_last_skb; > > @@ -318,6 +317,7 @@ struct mptcp_sock { > > u32 setsockopt_seq; > > char ca_name[TCP_CA_NAME_MAX]; > > struct mptcp_sock *dl_next; > > + struct sock *sendmsg_locked_sk; > > }; > > > > #define mptcp_data_lock(sk) spin_lock_bh(&(sk)->sk_lock.slock) > > -- > > 2.39.0 > > > > > > -- > Mat Martineau > Intel >