From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752084AbeBZGcH (ORCPT ); Mon, 26 Feb 2018 01:32:07 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:21327 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbeBZGcF (ORCPT ); Mon, 26 Feb 2018 01:32:05 -0500 Subject: Re: [PATCH 05/21] powerpc: Avoid comparison of unsigned long >= 0 in pfn_valid To: Mathieu Malaterre , Michael Ellerman Cc: linux-kernel@vger.kernel.org, Paul Mackerras , Jiri Slaby , linuxppc-dev@lists.ozlabs.org References: <20180225172236.29650-1-malat@debian.org> <20180225172236.29650-6-malat@debian.org> From: Christophe LEROY Message-ID: <55d52f37-c24d-c2da-43c6-73a55403d3b6@c-s.fr> Date: Mon, 26 Feb 2018 07:32:03 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180225172236.29650-6-malat@debian.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 25/02/2018 à 18:22, Mathieu Malaterre a écrit : > Rewrite comparison since all values compared are of type `unsigned long`. > > Fix a warning (treated as error in W=1): > > CC arch/powerpc/kernel/irq.o > In file included from ./include/linux/bug.h:5:0, > from ./include/linux/cpumask.h:13, > from ./include/linux/smp.h:13, > from ./include/linux/kernel_stat.h:5, > from arch/powerpc/kernel/irq.c:35: > ./include/linux/dma-mapping.h: In function ‘dma_map_resource’: > ./arch/powerpc/include/asm/page.h:129:32: error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits] > #define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr) > ^ > Suggested-by: Segher Boessenkool > Signed-off-by: Mathieu Malaterre > --- > arch/powerpc/include/asm/page.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h > index 8da5d4c1cab2..19dea64e7ed2 100644 > --- a/arch/powerpc/include/asm/page.h > +++ b/arch/powerpc/include/asm/page.h > @@ -126,7 +126,8 @@ extern long long virt_phys_offset; > > #ifdef CONFIG_FLATMEM > #define ARCH_PFN_OFFSET ((unsigned long)(MEMORY_START >> PAGE_SHIFT)) > -#define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr) > +#define pfn_valid(pfn) \ > + (((pfn) - ARCH_PFN_OFFSET) < (max_mapnr - ARCH_PFN_OFFSET)) What will happen when ARCH_PFN_OFFSET is not nul and pfn is lower than ARCH_PFN_OFFSET ? Christophe > #endif > > #define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT) >