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=-22.2 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,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 6B659C5519F for ; Wed, 18 Nov 2020 21:25:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C44C246B8 for ; Wed, 18 Nov 2020 21:25:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cSyGT1ni" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbgKRVYz (ORCPT ); Wed, 18 Nov 2020 16:24:55 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:26182 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726136AbgKRVYy (ORCPT ); Wed, 18 Nov 2020 16:24:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605734693; 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: in-reply-to:in-reply-to:references:references; bh=KEFetNrz9oaXnh8tgOcWj7yDkYGvE3+srDGUNa21rsk=; b=cSyGT1ninVPDOIo5LcIYffC2qC3E9/gytBswvIHFiuHg6cPTHeUt3Hpn7T53rrZBSMUoXd 8eU0oh2OhD02iwiN7BN/Muxa8UBmiu6v2u9uFjbMipnUGvgiatC2o51ObVCOHLJoBemDUc CM3vH9JhT531G24+uv/1IUGK8D8tZSo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-595-RQ9KstQPM4O4sGmFWuxI3A-1; Wed, 18 Nov 2020 16:24:49 -0500 X-MC-Unique: RQ9KstQPM4O4sGmFWuxI3A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BA99384A5E0; Wed, 18 Nov 2020 21:24:47 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 16ACF1346F; Wed, 18 Nov 2020 21:24:40 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id 0AILOeFo017597; Wed, 18 Nov 2020 16:24:40 -0500 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 0AILOcWa017593; Wed, 18 Nov 2020 16:24:38 -0500 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Wed, 18 Nov 2020 16:24:38 -0500 (EST) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Mike Snitzer cc: Randy Dunlap , Christian Borntraeger , linux-kernel@vger.kernel.org, Alasdair Kergon , dm-devel@redhat.com, Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org Subject: Re: md: dm-writeback: add __noreturn to BUG-ging function In-Reply-To: <20201118160748.GA754@redhat.com> Message-ID: References: <20201113225228.20563-1-rdunlap@infradead.org> <344abf76-9405-58ba-2dc4-27cab88c974d@de.ibm.com> <20201117163147.GA27243@redhat.com> <20201118154944.GB545@redhat.com> <20201118160748.GA754@redhat.com> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 18 Nov 2020, Mike Snitzer wrote: > On Wed, Nov 18 2020 at 10:49am -0500, > Mike Snitzer wrote: > > > I don't think my suggestion will help.. given it'd still leave > > persistent_memory_claim() without a return statement. > > > > Think it worthwhile to just add a dummy 'return 0;' after the BUG(). > > Decided to go with this, now staged for 5.11: > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-5.11&id=a1e4865b4dda7071f3707f7e551289ead66e38b1 Hi I would just use "return -EOPNOTSUPP;" and drop the "#ifdef DM_WRITECACHE_HAS_PMEM" that you added. That BUG/return -EOPNOTSUPP code can't happen at all - if DM_WRITECACHE_HAS_PMEM is not defined, WC_MODE_PMEM(wc) always returns false - so persistent_memory_claim and BUG() can't ever be called. And if it can't be called, you don't need to add a code that prints an error in that case. If we don't have DM_WRITECACHE_HAS_PMEM, the compiler optimizer will remove all the code guarded with if (WC_MODE_PMEM(wc)) as unreachable. Mikulas From: Mikulas Patocka Subject: [PATCH] dm writecache: remove BUG() and fail gracefully insteadfor-nextdm-5.11 Building on arch/s390/ results in this build error: cc1: some warnings being treated as errors ../drivers/md/dm-writecache.c: In function 'persistent_memory_claim': ../drivers/md/dm-writecache.c:323:1: error: no return statement in function returning non-void [-Werror=return-type] Fix this by replacing the BUG() with a -EOPNOTSUPP return. Fixes: 48debafe4f2f ("dm: add writecache target") Cc: stable@vger.kernel.org # v4.18+ Reported-by: Randy Dunlap Signed-off-by: Mikulas Patocka Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c +++ linux-2.6/drivers/md/dm-writecache.c @@ -319,7 +319,7 @@ err1: #else static int persistent_memory_claim(struct dm_writecache *wc) { - BUG(); + return -EOPNOTSUPP; } #endif 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=-22.2 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,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 1DE02C5519F for ; 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Wed, 18 Nov 2020 21:24:49 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 0AILOl68031838 for ; Wed, 18 Nov 2020 16:24:47 -0500 Received: by smtp.corp.redhat.com (Postfix) id B91446064B; Wed, 18 Nov 2020 21:24:47 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 16ACF1346F; Wed, 18 Nov 2020 21:24:40 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id 0AILOeFo017597; Wed, 18 Nov 2020 16:24:40 -0500 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 0AILOcWa017593; Wed, 18 Nov 2020 16:24:38 -0500 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Wed, 18 Nov 2020 16:24:38 -0500 (EST) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Mike Snitzer In-Reply-To: <20201118160748.GA754@redhat.com> Message-ID: References: <20201113225228.20563-1-rdunlap@infradead.org> <344abf76-9405-58ba-2dc4-27cab88c974d@de.ibm.com> <20201117163147.GA27243@redhat.com> <20201118154944.GB545@redhat.com> <20201118160748.GA754@redhat.com> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-loop: dm-devel@redhat.com Cc: linux-s390@vger.kernel.org, Vasily Gorbik , Heiko Carstens , Randy Dunlap , linux-kernel@vger.kernel.org, Christian Borntraeger , dm-devel@redhat.com, Alasdair Kergon Subject: Re: [dm-devel] md: dm-writeback: add __noreturn to BUG-ging function X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Wed, 18 Nov 2020, Mike Snitzer wrote: > On Wed, Nov 18 2020 at 10:49am -0500, > Mike Snitzer wrote: > > > I don't think my suggestion will help.. given it'd still leave > > persistent_memory_claim() without a return statement. > > > > Think it worthwhile to just add a dummy 'return 0;' after the BUG(). > > Decided to go with this, now staged for 5.11: > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-5.11&id=a1e4865b4dda7071f3707f7e551289ead66e38b1 Hi I would just use "return -EOPNOTSUPP;" and drop the "#ifdef DM_WRITECACHE_HAS_PMEM" that you added. That BUG/return -EOPNOTSUPP code can't happen at all - if DM_WRITECACHE_HAS_PMEM is not defined, WC_MODE_PMEM(wc) always returns false - so persistent_memory_claim and BUG() can't ever be called. And if it can't be called, you don't need to add a code that prints an error in that case. If we don't have DM_WRITECACHE_HAS_PMEM, the compiler optimizer will remove all the code guarded with if (WC_MODE_PMEM(wc)) as unreachable. Mikulas From: Mikulas Patocka Subject: [PATCH] dm writecache: remove BUG() and fail gracefully insteadfor-nextdm-5.11 Building on arch/s390/ results in this build error: cc1: some warnings being treated as errors ../drivers/md/dm-writecache.c: In function 'persistent_memory_claim': ../drivers/md/dm-writecache.c:323:1: error: no return statement in function returning non-void [-Werror=return-type] Fix this by replacing the BUG() with a -EOPNOTSUPP return. Fixes: 48debafe4f2f ("dm: add writecache target") Cc: stable@vger.kernel.org # v4.18+ Reported-by: Randy Dunlap Signed-off-by: Mikulas Patocka Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c +++ linux-2.6/drivers/md/dm-writecache.c @@ -319,7 +319,7 @@ err1: #else static int persistent_memory_claim(struct dm_writecache *wc) { - BUG(); + return -EOPNOTSUPP; } #endif -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel