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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 155A3C46477 for ; Sat, 15 Jun 2019 02:20:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC70D20679 for ; Sat, 15 Jun 2019 02:20:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726218AbfFOCUj (ORCPT ); Fri, 14 Jun 2019 22:20:39 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:57372 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725812AbfFOCUj (ORCPT ); Fri, 14 Jun 2019 22:20:39 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id DC3BF134116D6; Fri, 14 Jun 2019 19:20:38 -0700 (PDT) Date: Fri, 14 Jun 2019 19:20:38 -0700 (PDT) Message-Id: <20190614.192038.685198515789181601.davem@davemloft.net> To: sunilmut@microsoft.com Cc: stefanha@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, decui@microsoft.com Subject: Re: [PATCH net-next] vsock: correct removal of socket from the list From: David Miller In-Reply-To: References: X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Fri, 14 Jun 2019 19:20:39 -0700 (PDT) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Sunil Muthuswamy Date: Thu, 13 Jun 2019 03:52:27 +0000 > The current vsock code for removal of socket from the list is both > subject to race and inefficient. It takes the lock, checks whether > the socket is in the list, drops the lock and if the socket was on the > list, deletes it from the list. This is subject to race because as soon > as the lock is dropped once it is checked for presence, that condition > cannot be relied upon for any decision. It is also inefficient because > if the socket is present in the list, it takes the lock twice. > > Signed-off-by: Sunil Muthuswamy Applied.