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 80321C433F5 for ; Thu, 9 Dec 2021 12:16:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237278AbhLIMU2 (ORCPT ); Thu, 9 Dec 2021 07:20:28 -0500 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:6971 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237258AbhLIMU2 (ORCPT ); Thu, 9 Dec 2021 07:20:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.co.jp; i=@amazon.co.jp; q=dns/txt; s=amazon201209; t=1639052216; x=1670588216; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RWlbifQ9a9AiycMGPMulphDDQPX16BnMiBreU0jK2tU=; b=c48OOC3Qdh5JoU9fjEa02xyaEBXzN9OGSCjvJqVHbiWuVxRixNoTgvb1 isVg93co0kO5t7/LHVgh1ZEz/khX6wnyYXDBo+Un7vCcO4PWPOXBLHuhL v3d0Om2Lrs5xHs3hVDw45MXz6YjzTqkE+YwwM8MuKqupaeX7Rw7lM9xBJ A=; X-IronPort-AV: E=Sophos;i="5.88,192,1635206400"; d="scan'208";a="179641552" Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO email-inbound-relay-iad-1a-8691d7ea.us-east-1.amazon.com) ([10.25.36.214]) by smtp-border-fw-9102.sea19.amazon.com with ESMTP; 09 Dec 2021 12:16:54 +0000 Received: from EX13MTAUWB001.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan2.iad.amazon.com [10.40.163.34]) by email-inbound-relay-iad-1a-8691d7ea.us-east-1.amazon.com (Postfix) with ESMTPS id 620F3C0971; Thu, 9 Dec 2021 12:16:52 +0000 (UTC) Received: from EX13D04ANC001.ant.amazon.com (10.43.157.89) by EX13MTAUWB001.ant.amazon.com (10.43.161.207) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Thu, 9 Dec 2021 12:16:51 +0000 Received: from 88665a182662.ant.amazon.com (10.43.161.223) by EX13D04ANC001.ant.amazon.com (10.43.157.89) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Thu, 9 Dec 2021 12:16:48 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , Subject: Re: [PATCH v2 net-next] tcp: Warn if sock_owned_by_user() is true in tcp_child_process(). Date: Thu, 9 Dec 2021 21:16:44 +0900 Message-ID: <20211209121644.96758-1-kuniyu@amazon.co.jp> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.43.161.223] X-ClientProxiedBy: EX13D02UWC001.ant.amazon.com (10.43.162.243) To EX13D04ANC001.ant.amazon.com (10.43.157.89) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Paolo Abeni Date: Thu, 09 Dec 2021 12:59:21 +0100 > On Thu, 2021-12-09 at 20:07 +0900, Kuniyuki Iwashima wrote: >> From: Eric Dumazet >> Date: Thu, 9 Dec 2021 00:00:35 -0800 >>> On Wed, Dec 8, 2021 at 5:33 PM Kuniyuki Iwashima wrote: >>>> >>>> While creating a child socket from ACK (not TCP Fast Open case), before >>>> v2.3.41, we used to call bh_lock_sock() later than now; it was called just >>>> before tcp_rcv_state_process(). The full socket was put into an accept >>>> queue and exposed to other CPUs before bh_lock_sock() so that process >>>> context might have acquired the lock by then. Thus, we had to check if any >>>> process context was accessing the socket before tcp_rcv_state_process(). >>>> >>> >>> I think you misunderstood me. >>> >>> I think this code is not dead yet, so I would : >>> >>> Not include a Fixes: tag to avoid unnecessary backports (of a patch >>> and its revert) >>> >>> If you want to get syzbot coverage for few releases, especially with >>> MPTCP and synflood, >>> you can then submit a patch like the following. >> >> Sorry, I got on the same page. >> Let me take a look at MPTCP, then if I still think it is dead code, I will >> submit the patch. > > For the records, I think the 'else' branch should be reachble with > MPTCP in some non trivial scenario, e.g. MPJ subflows 3WHS racing with > setsockopt on the main MPTCP socket. I'm unsure if syzbot could catch > that, as it needs mptcp endpoints configuration. Ah, I was wrong. Thanks for explaining! > > Cheers, > > Paolo