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=-19.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 16445C433EF for ; Wed, 8 Sep 2021 14:40:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D786660EFE for ; Wed, 8 Sep 2021 14:40:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349338AbhIHOl1 (ORCPT ); Wed, 8 Sep 2021 10:41:27 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:41043 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231164AbhIHOl0 (ORCPT ); Wed, 8 Sep 2021 10:41:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631112017; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=F0mS/4vH+akbhx3KmKiVesBsbwWaeG1PhCRwFwsmwm4=; b=XhJNvncY/kFTOOvP/oc6U+NuHKobjBRhetort0Q+mJSDosGIaKl+RxkDH87kR+o1fYdlLw m9LRkzOzOA89C+2l9nd5weHfs3F6HqvGtAm+ilZjOi7tJRlvYez84Jd1lNCOuX1C2+daZd UL0+g4+bRi6jVw4lCwHBXt5LQYdY0wc= Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-17-8aXf3lXuMAmVuIIEd5ErFQ-1; Wed, 08 Sep 2021 10:40:16 -0400 X-MC-Unique: 8aXf3lXuMAmVuIIEd5ErFQ-1 Received: by mail-qt1-f197.google.com with SMTP id o7-20020a05622a138700b002a0e807258bso2452694qtk.13 for ; Wed, 08 Sep 2021 07:40:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:subject:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=F0mS/4vH+akbhx3KmKiVesBsbwWaeG1PhCRwFwsmwm4=; b=fClKXg0mEtLww3DMEolOEWlri4RPH+xUEsBfgIbarU3m2uF/kPt1ZYZ/8W0iW8g96i rl6JuVZv6ivZEmER3kOLu7P1k2/1+bsUlF/qFWgse55ov66XgCnZKTa2l2EvA46M6W+H 5lyQn44VNbjUJODYTYUA9GLHHRccb+PLK0w8khxfiaCY1wJZ9YIh5wLM4pVH8xMnV0Pq pbxhM8+TxiABGo3favNmLztNOHeN2JEWCFx0hw5H1/zg5Eprcc3r3EHbHcSZhcVcRauv Iv8/WyANf2wAYSd5Q3Axda9362ZYzMw2hvuqSPvY5klsvp6Mosw8QJl4Gqx8dtwOMoeN AZyA== X-Gm-Message-State: AOAM531ngU6z+cJgypoitAJrSOeo3fmMliirDbv6wyh5GPnc5wRjG9ty YYDkausehOo6YCL7dr7A4p0ptFs2i6pRGZq2w/zdX8Vi1LonGz73O8B3xsr0aOOoYjDLCp2UY8B 8McLNl/mVK7GF7CXnniRJcKxW X-Received: by 2002:ad4:5f06:: with SMTP id fo6mr4293723qvb.32.1631112016420; Wed, 08 Sep 2021 07:40:16 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw/QsCtIYTif18mNNXhu/aYeBjgKlf815YDrQE6oMXEjqwGIZImLb3bnFRl+eOk1YZkdCP9HA== X-Received: by 2002:ad4:5f06:: with SMTP id fo6mr4293695qvb.32.1631112016200; Wed, 08 Sep 2021 07:40:16 -0700 (PDT) Received: from llong.remote.csb ([2601:191:8500:76c0::cdbc]) by smtp.gmail.com with ESMTPSA id d68sm1882756qke.19.2021.09.08.07.40.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Sep 2021 07:40:15 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Subject: Re: [PATCH v2] lockdep: Let lock_is_held_type() detect recursive read as read To: Boqun Feng , Sebastian Andrzej Siewior Cc: Waiman Long , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Will Deacon , Thomas Gleixner References: <20210901162255.u2vhecaxgjsjfdtc@linutronix.de> <9af2b074-9fcf-5aea-f37d-9b2482146489@redhat.com> <20210903084001.lblecrvz4esl4mrr@linutronix.de> Message-ID: <959eddbd-799b-3b10-0f30-0209f883d5ed@redhat.com> Date: Wed, 8 Sep 2021 10:40:14 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/7/21 10:16 PM, Boqun Feng wrote: > On Fri, Sep 03, 2021 at 10:40:01AM +0200, Sebastian Andrzej Siewior wrote: >> lock_is_held_type(, 1) detects acquired read locks. It only recognized >> locks acquired with lock_acquire_shared(). Read locks acquired with >> lock_acquire_shared_recursive() are not recognized because a `2' is >> stored as the read value. >> >> Rework the check to additionally recognise lock's read value one and two >> as a read held lock. >> >> Fixes: e918188611f07 ("locking: More accurate annotations for read_lock()") >> Signed-off-by: Sebastian Andrzej Siewior >> --- >> v1…v2: >> - simplify the read check to !!read as suggested by Waiman Long. >> >> kernel/locking/lockdep.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> --- a/kernel/locking/lockdep.c >> +++ b/kernel/locking/lockdep.c >> @@ -5366,7 +5366,7 @@ int __lock_is_held(const struct lockdep_ >> struct held_lock *hlock = curr->held_locks + i; >> >> if (match_held_lock(hlock, lock)) { >> - if (read == -1 || hlock->read == read) >> + if (read == -1 || hlock->read == !!read) > I think this should be: > > !!hlock->read == read > > With that, > > Acked-by: Boqun Feng > You are right. It should be the other way around. read can only be -1, 0, 1 while hlock->read can be 0, 1, 2. Cheers, Longman