Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753305AbbD0XTy (ORCPT ); Mon, 27 Apr 2015 19:19:54 -0400 Received: from mail-ob0-f175.google.com ([209.85.214.175]:34102 "EHLO mail-ob0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753176AbbD0XTw (ORCPT ); Mon, 27 Apr 2015 19:19:52 -0400 MIME-Version: 1.0 In-Reply-To: <553EC325.6060401@nod.at> References: <1427292151-3835-1-git-send-email-richard@nod.at> <1427292151-3835-2-git-send-email-richard@nod.at> <20150427213558.GA22780@bshelton-desktop> <553EB5E4.3050309@nod.at> <20150427223630.GA11721@bshelton-desktop> <553EBB4A.1040905@nod.at> <20150427225307.GC32500@ld-irv-0074> <553EBEDD.9050204@nod.at> <553EC325.6060401@nod.at> Date: Mon, 27 Apr 2015 16:19:51 -0700 Message-ID: Subject: Re: [PATCH 1/3] mtd: nand: Add on-die ECC support From: Brian Norris To: Richard Weinberger Cc: Ben Shelton , "linux-mtd@lists.infradead.org" , Linux Kernel , David Woodhouse , Punnaiah Choudary Kalluri Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2631 Lines: 56 On Mon, Apr 27, 2015 at 4:15 PM, Richard Weinberger wrote: > Am 28.04.2015 um 01:10 schrieb Brian Norris: >> On Mon, Apr 27, 2015 at 3:57 PM, Richard Weinberger wrote: >>> Am 28.04.2015 um 00:53 schrieb Brian Norris: >>>> On Tue, Apr 28, 2015 at 12:42:18AM +0200, Richard Weinberger wrote: >>>>> Am 28.04.2015 um 00:36 schrieb Ben Shelton: >>>>>>>> When I build this without CONFIG_MTD_NAND_ECC_ON_DIE enabled, I get the >>>>>>>> following warning here: >>>>>>>> >>>>>>>> In file included from drivers/mtd/nand/nand_base.c:46:0: >>>>>>>> include/linux/mtd/nand_ondie.h: In function 'nand_read_subpage_on_die': >>>>>>>> include/linux/mtd/nand_ondie.h:28:1: warning: no return statement in function returning non-void [-Wreturn-type] >>>>>>>> include/linux/mtd/nand_ondie.h: In function 'nand_read_page_on_die': >>>>>>>> include/linux/mtd/nand_ondie.h:34:1: warning: no return statement in function returning non-void [-Wreturn-type] >>>>>>>> >>>>>>>> Perhaps return an error code here, even though you'll never get past the BUG()? >>>>>>> >>>>>>> What gcc is this? >>>>>>> gcc 4.8 here does not warn, I thought it is smart enough that this function does never >>>>>>> return. Can it be that your .config has CONFIG_BUG=n? >>>>>>> Anyway, this functions clearly needs a return statement. :) >>>>>> >>>>>> gcc 4.7.2, and you are correct that I had CONFIG_BUG off. :) >>>>> >>>>> Yeah, just noticed that BUG() with CONFIG_BUG=n does not have >>>>> a nonreturn attribute. So, gcc cannot know... >>>> >>>> But it's an obvious infinite loop... all of my toolchains (4.2, 4.5, >>>> 4.6, 4.8) are able to compile this without complaining (gcc -Wall): >>>> >>>> int test() { do { } while (1); } >>> >>> Not here. gcc 4.8 warns on that. >>> As soon I add __attribute__ ((noreturn)) it does not longer complain. >> >> Huh? Maybe I have a crazy modified gcc. >> >> $ gcc --version >> gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2 >> Copyright (C) 2013 Free Software Foundation, Inc. >> This is free software; see the source for copying conditions. There is NO >> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. >> >> $ gcc -Wall -Wextra -c a.c >> $ cat a.c >> int test() { do {} while (1); } > > Make test static and gcc will warn. Hmm. That's a strange distinction for gcc to make. Maybe because of the potential for inlining? Still seems odd. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/