From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932407AbbCIU37 (ORCPT ); Mon, 9 Mar 2015 16:29:59 -0400 Received: from mail-la0-f42.google.com ([209.85.215.42]:35653 "EHLO mail-la0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932155AbbCIU3x (ORCPT ); Mon, 9 Mar 2015 16:29:53 -0400 Message-ID: <54FE02C1.9090803@cogentembedded.com> Date: Mon, 09 Mar 2015 23:29:53 +0300 From: Sergei Shtylyov User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Arnd Bergmann , David Woodhouse , Brian Norris CC: Jingoo Han , linux-mtd@lists.infradead.org, Ezequiel Garcia , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] MTD: cfi: reduce stack size References: <2376719.UMjvd0rdnO@wuerfel> In-Reply-To: <2376719.UMjvd0rdnO@wuerfel> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello. On 3/9/2015 10:34 PM, Arnd Bergmann wrote: > The cfi_staa_write_buffers function uses a large amount of kernel stack > whenever CONFIG_MTD_MAP_BANK_WIDTH_32 is set, and that results in a > warning on ARM allmodconfig builds: > drivers/mtd/chips/cfi_cmdset_0020.c: In function 'cfi_staa_write_buffers': > drivers/mtd/chips/cfi_cmdset_0020.c:651:1: warning: the frame size of 1208 bytes is larger than 1024 bytes [-Wframe-larger-than=] > It turns out that this is largely a result of a suboptimal implementation > of map_word_andequal(). Replacing this function with a straightforward > one reduces the stack size in this function by exactly 200 bytes, > shrinks the .text segment for this file from 27648 bytes to 26608 bytes, > and makes the warning go away. > Signed-off-by: Arnd Bergmann > diff --git a/include/linux/mtd/map.h b/include/linux/mtd/map.h > index 5f487d776411..7b5841663d4f 100644 > --- a/include/linux/mtd/map.h > +++ b/include/linux/mtd/map.h > @@ -314,7 +314,15 @@ static inline map_word map_word_or(struct map_info *map, map_word val1, map_word > return r; > } > > -#define map_word_andequal(m, a, b, z) map_word_equal(m, z, map_word_and(m, a, b)) > +static inline int map_word_andequal(struct map_info *map, map_word val1, map_word val2, map_word val3) > +{ > + int i; I think empty line is needed here. > + for (i=0; i < map_words(map); i++) { Could you please be consistent and surround all binary operators with spaces, like on the line below? > + if ((val1.x[i] & val2.x[i]) != val3.x[i]) > + return 0; > + } > + return 1; > +} [...] WBR, Sergei