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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 35427C04EB8 for ; Tue, 4 Dec 2018 21:08:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3C552082D for ; Tue, 4 Dec 2018 21:08:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F3C552082D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726069AbeLDVIY (ORCPT ); Tue, 4 Dec 2018 16:08:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47000 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725867AbeLDVIY (ORCPT ); Tue, 4 Dec 2018 16:08:24 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A5589307CDC5; Tue, 4 Dec 2018 21:08:23 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-55.bos.redhat.com [10.18.17.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id D224C60BE5; Tue, 4 Dec 2018 21:08:22 +0000 (UTC) Subject: Re: [PATCH v2 21/24] locking/lockdep: Verify whether lock objects are small enough to be used as class keys To: Bart Van Assche , mingo@redhat.com Cc: peterz@infradead.org, tj@kernel.org, johannes.berg@intel.com, linux-kernel@vger.kernel.org, Johannes Berg References: <20181204002833.55452-1-bvanassche@acm.org> <20181204002833.55452-22-bvanassche@acm.org> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181204002833.55452-22-bvanassche@acm.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Tue, 04 Dec 2018 21:08:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/2018 07:28 PM, Bart Van Assche wrote: > Cc: Peter Zijlstra > Cc: Waiman Long > Cc: Johannes Berg > Signed-off-by: Bart Van Assche > --- > kernel/locking/lockdep.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > index c936fce5b9d7..b4772e5fc176 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -727,6 +727,15 @@ static bool assign_lock_key(struct lockdep_map *lock) > { > unsigned long can_addr, addr = (unsigned long)lock; > > + /* > + * lockdep_free_key_range() assumes that struct lock_class_key > + * objects do not overlap. Since we use the address of lock > + * objects as class key for static objects, check whether the > + * size of lock_class_key objects does not exceed the size of > + * the smallest lock object. > + */ > + BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t)); > + > if (__is_kernel_percpu_address(addr, &can_addr)) > lock->key = (void *)can_addr; > else if (__is_module_percpu_address(addr, &can_addr)) I don't understand what this check is for. lock_class_key and spinlock are different objects. Their relative size shouldn't matter. Cheers, Longman