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=-6.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 BA642C433DF for ; Wed, 29 Jul 2020 14:57:50 +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 8E75420829 for ; Wed, 29 Jul 2020 14:57:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=xen.org header.i=@xen.org header.b="1WOxbrDc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E75420829 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k0nWG-00077B-EK; Wed, 29 Jul 2020 14:57:24 +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 1k0nWE-000774-Na for xen-devel@lists.xenproject.org; Wed, 29 Jul 2020 14:57:22 +0000 X-Inumbo-ID: ce2fe8be-d1ab-11ea-aa05-12813bfff9fa Received: from mail.xenproject.org (unknown [104.130.215.37]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id ce2fe8be-d1ab-11ea-aa05-12813bfff9fa; Wed, 29 Jul 2020 14:57:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=QhHEaHPkW4uhDh2CPLU4RGxx9scYOzNumVO2pU8mGGw=; b=1WOxbrDcGnX1WwsrimygZXLZvZ VtFZkOJnD5z3bXkaz/vBK37BiCKEA1LEGVogG4T385YwjvS5INB/Y2aT5AS6RORdCF/qGmBM+RNfT eSgqshUfzZEDvp9E6G2YwdX9Y7Z4HrC29UF6E8sReTz2EnRU5vrnFp/uuEPnK8Aa1L1Q=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k0nWB-0002Pm-6n; Wed, 29 Jul 2020 14:57:19 +0000 Received: from 54-240-197-236.amazon.com ([54.240.197.236] helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1k0nWA-0003s2-V0; Wed, 29 Jul 2020 14:57:19 +0000 Subject: Re: [PATCH] xen/spinlock: move debug helpers inside the locked regions To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= References: <20200729111330.64549-1-roger.pau@citrix.com> <16dd0f04-598b-8b84-8a25-6b89af9214d7@xen.org> <20200729135045.GD7191@Air-de-Roger> From: Julien Grall Message-ID: Date: Wed, 29 Jul 2020 15:57:16 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200729135045.GD7191@Air-de-Roger> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Igor Druzhinin , Stefano Stabellini , Wei Liu , Andrew Cooper , Ian Jackson , George Dunlap , Jan Beulich , xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Hi Roger, On 29/07/2020 14:50, Roger Pau Monné wrote: > On Wed, Jul 29, 2020 at 02:37:44PM +0100, Julien Grall wrote: >> Hi Roger, >> >> On 29/07/2020 12:13, Roger Pau Monne wrote: >>> Debug helpers such as lock profiling or the invariant pCPU assertions >>> must strictly be performed inside the exclusive locked region, or else >>> races might happen. >>> >>> Note the issue was not strictly introduced by the pointed commit in >>> the Fixes tag, since lock stats where already incremented before the >>> barrier, but that commit made it more apparent as manipulating the cpu >>> field could happen outside of the locked regions and thus trigger the >>> BUG_ON. >> >> From the wording, it is not entirely clear which BUG_ON() you are referring >> to. I am guessing, it is the one in rel_lock(). Am I correct? > > Yes, that's right. Expanding to: > > "... and thus trigger the BUG_ON in rel_lock()." would be better. Looks good to me. With that: Reviewed-by: Julien Grall I am happy to do the update on commit if there is no more comments. Cheers, -- Julien Grall