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 Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D61ACC4167E for ; Tue, 1 Mar 2022 03:04:05 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-4.v29.lw.sourceforge.com) by sfs-ml-4.v29.lw.sourceforge.com with esmtp (Exim 4.94.2) (envelope-from ) id 1nOso1-0003c9-AJ; Tue, 01 Mar 2022 03:04:04 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-4.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nOso0-0003bz-Dv for linux-f2fs-devel@lists.sourceforge.net; Tue, 01 Mar 2022 03:04:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:Content-Type:MIME-Version :In-Reply-To:References:Message-ID:Date:Subject:CC:To:From: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=1Cll4LDt47AmgsYpW4N5Qr25Ln/dd6n3OS7ya/cdsmQ=; b=L1Jj3FdHYVDZFJo5Yt+sYHrVDS hOwodCLK2OleKqYQyQ8LfLQ7KH0Eng1vCGLpOWhifUqwF33iFMXiQ7sMrJAtlMgKk5hKTkbhg9/5h oyCBHWtAitRamwzamPetCxmnWMutDhUx7iiQeLeYmYvtAXC/a9i/32xY7111fgxjQ+UM=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:Content-Type:MIME-Version:In-Reply-To: References:Message-ID:Date:Subject:CC:To:From: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=1Cll4LDt47AmgsYpW4N5Qr25Ln/dd6n3OS7ya/cdsmQ=; b=VOytzeb3PzZjs0dryGqPm4dWOJ /gVLOJv0hfzF5/63J6CE0MB2pn8sztWDqqSq+AqZqqcVySo0gEg04OAmpiN2xeMh2FD+F9TKniSXz P5DA2+FKvbWGQHM2NypYBdMFNOaAMg4z9SfxZ8b2/E341sFPLfSblK5ROc9dEgwpBhs4=; Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.94.2) id 1nOsny-000kdi-4J for linux-f2fs-devel@lists.sourceforge.net; Tue, 01 Mar 2022 03:04:03 +0000 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-267-9MSeLLg1PRGi9Q5Mk98pjw-1; Tue, 01 Mar 2022 03:03:54 +0000 X-MC-Unique: 9MSeLLg1PRGi9Q5Mk98pjw-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.28; Tue, 1 Mar 2022 03:03:52 +0000 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.028; Tue, 1 Mar 2022 03:03:52 +0000 From: David Laight To: 'Matthew Wilcox' , Linus Torvalds Thread-Topic: [PATCH 2/6] treewide: remove using list iterator after loop body as a ptr Thread-Index: AQHYLOAn+DU/OogLf0+tiSFmjztyUKyp1n9A Date: Tue, 1 Mar 2022 03:03:52 +0000 Message-ID: <198022f201814cdc9384ef083741185e@AcuMS.aculab.com> References: <20220228110822.491923-1-jakobkoschel@gmail.com> <20220228110822.491923-3-jakobkoschel@gmail.com> <2e4e95d6-f6c9-a188-e1cd-b1eae465562a@amd.com> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US X-Headers-End: 1nOsny-000kdi-4J Subject: Re: [f2fs-dev] [PATCH 2/6] treewide: remove using list iterator after loop body as a ptr X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-wireless , "alsa-devel@alsa-project.org" , KVM list , "Gustavo A. R. Silva" , "linux-iio@vger.kernel.org" , "nouveau@lists.freedesktop.org" , Rasmus Villemoes , dri-devel , Cristiano Giuffrida , "Bos, H.J." , "linux1394-devel@lists.sourceforge.net" , "drbd-dev@lists.linbit.com" , linux-arch , CIFS , "linux-aspeed@lists.ozlabs.org" , linux-scsi , linux-rdma , "linux-staging@lists.linux.dev" , amd-gfx list , Jason Gunthorpe , "intel-wired-lan@lists.osuosl.org" , "kgdb-bugreport@lists.sourceforge.net" , "bcm-kernel-feedback-list@broadcom.com" , Dan Carpenter , Linux Media Mailing List , Kees Cook , Arnd Bergman , Linux PM , intel-gfx , Brian Johannesmeyer , Nathan Chancellor , dma , Christophe JAILLET , Jakob Koschel , "v9fs-developer@lists.sourceforge.net" , linux-tegra , Thomas Gleixner , Andy Shevchenko , Linux ARM , "linux-sgx@vger.kernel.org" , linux-block , Netdev , "linux-usb@vger.kernel.org" , "samba-technical@lists.samba.org" , Linux Kernel Mailing List , Linux F2FS Dev Mailing List , "tipc-discussion@lists.sourceforge.net" , Linux Crypto Mailing List , linux-fsdevel , "linux-mediatek@lists.infradead.org" , Andrew Morton , linuxppc-dev , =?iso-8859-1?Q?Christian_K=F6nig?= , Mike Rapoport Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net From: Matthew Wilcox > Sent: 28 February 2022 20:16 > > On Mon, Feb 28, 2022 at 12:10:24PM -0800, Linus Torvalds wrote: > > We can do > > > > typeof(pos) pos > > > > in the 'for ()' loop, and never use __iter at all. > > > > That means that inside the for-loop, we use a _different_ 'pos' than outside. > > Then we can never use -Wshadow ;-( I'd love to be able to turn it on; > it catches real bugs. > > > +#define list_for_each_entry(pos, head, member) \ > > + for (typeof(pos) pos = list_first_entry(head, typeof(*pos), member); \ > > + !list_entry_is_head(pos, head, member); \ > > pos = list_next_entry(pos, member)) Actually can't you use 'pos' to temporarily hold the address of 'member'. Something like: for (pos = (void *)head; \ pos ? ((pos = (void *)pos - offsetof(member)), 1) : 0; \ pos = (void *)pos->next) So that 'pos' is NULL if the loop terminates. No pointers outside structures are generated. Probably need to kill list_entry_is_head() - or it just checks for NULL. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel