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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 7EFC3C2B9F7 for ; Fri, 28 May 2021 13:42:13 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 446DB61284 for ; Fri, 28 May 2021 13:42:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 446DB61284 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.133936.249446 (Exim 4.92) (envelope-from ) id 1lmckU-0005no-Ev; Fri, 28 May 2021 13:42:02 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 133936.249446; Fri, 28 May 2021 13:42:02 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lmckU-0005nh-Bo; Fri, 28 May 2021 13:42:02 +0000 Received: by outflank-mailman (input) for mailman id 133936; Fri, 28 May 2021 13:42:00 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lmckS-0005nI-Mp for xen-devel@lists.xenproject.org; Fri, 28 May 2021 13:42:00 +0000 Received: from smtp-out2.suse.de (unknown [195.135.220.29]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id b6ec4b3c-0d6f-48da-a4ef-c1438f7acfee; Fri, 28 May 2021 13:41:59 +0000 (UTC) Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id F3DB11FD2E; Fri, 28 May 2021 13:41:58 +0000 (UTC) Received: from imap3-int (imap-alt.suse-dmz.suse.de [192.168.254.47]) by imap.suse.de (Postfix) with ESMTP id C3E6D11A98; Fri, 28 May 2021 13:41:58 +0000 (UTC) Received: from director2.suse.de ([192.168.254.72]) by imap3-int with ESMTPSA id nhWmLibzsGAqUQAALh3uQQ (envelope-from ); Fri, 28 May 2021 13:41:58 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: b6ec4b3c-0d6f-48da-a4ef-c1438f7acfee DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1622209319; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dsxnym2Edb8D8ioPAlnFYNHlty7zrn/wpCqrfApi17Y=; b=Qt+UkaJTUz5S8s5jqrK/QYBHB39/clK8RBPdLYyjqN/qKDBl6m4os8wcSHxgg8NTqINWIZ 0s50OnLWtRM3O/YQ5+XAzW2IlG39KcBYOzoZ+mnoJZza4qLMbWaYHBbkt78BW2+ZoM/ndw j16wJnj0k4NVySgUri3398QJKZO47bQ= Subject: Re: [PATCH v6 1/3] evtchn: slightly defer lock acquire where possible To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper , George Dunlap , Ian Jackson , Wei Liu , Stefano Stabellini , Julien Grall References: <01bbf3d4-ca6a-e837-91fe-b34aa014564c@suse.com> <5939858e-1c7c-5658-bc2d-0c9024c74040@suse.com> <938eb888-ec15-feb1-19f7-b90dfee822ae@xen.org> <27d54d81-bec8-5bc7-39cd-60e9761e726b@suse.com> <079f2f2a-0797-b650-ff47-7e595ab29589@xen.org> From: Jan Beulich Message-ID: <68f032b6-62a0-c472-8b10-ec26d0407c93@suse.com> Date: Fri, 28 May 2021 15:41:53 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit On 28.05.2021 15:31, Roger Pau Monné wrote: > I think I'm being extremely dull here, sorry. From your text I > understand that the value returned by is_port_valid could be stale by > the time the user reads it? > > I think there's some condition that makes this value stale, and it's > not the common case? It's evtchn_destroy() running in parallel which can have this effect. Jan