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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 7BAE1C282C4 for ; Tue, 12 Feb 2019 18:07:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4CCDF2229F for ; Tue, 12 Feb 2019 18:07:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="nBIrEpUB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731614AbfBLSHU (ORCPT ); Tue, 12 Feb 2019 13:07:20 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:42863 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727843AbfBLSHU (ORCPT ); Tue, 12 Feb 2019 13:07:20 -0500 Received: by mail-pg1-f196.google.com with SMTP id d72so1599592pga.9 for ; Tue, 12 Feb 2019 10:07:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=Orczz7OzGsol9BSTi3enSHRqZox7M6jz44V37KHUss4=; b=nBIrEpUBqKJ6uy8d9GEQpKeHVfNWOuexJcGisSwO/2YBJBXA3AcIhQQ9yCVkiocJ6I 4DXxFIT4ILIHWFMsHBdprfM5uaRQs871OoIkIoxghQcnvONQ34Fm9nau0ExtxpmjKdfq ymozvuG2rlJmHIFBRPQ5n6xRZaBaI7qzyjMAnbs7qt6NPOXp8fR++L1+n6B1sJWx1gww Sm39qn+01E3mv6QiwBne+3IcoiF+opfB5u7J0mZyEcrO2zHTt4uGAmxNCu9DReBlPXNW +wrLCqqADis2txKVpCn45b/wznnJeaVpmuIBaHbLr0C4LiuLMfz9T5DHAI852g4YNQpJ fxbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=Orczz7OzGsol9BSTi3enSHRqZox7M6jz44V37KHUss4=; b=YhLDti3TWaYrl+7mEkcQhXynmI4TthVfxh2KpNjhBN9mG4D0LkddUlD0OfALMhF0Ub xVDaKGLEaRuW0hXjCmE6NbV/Ka7ruGmfR4Qc5oPwg8/g6HPRG/POr5RdiJ1ANRvSfKM1 BfrYKvH449IEfctFKIsVfk2CxPDb5TVnZBGeObh0rxXoht9IYV7Y6xfHJ5lJlFfnV+RG WCjzFrBYg220/PDbaH5BdeD6hKtqVd3X0JSDqvK8OPkMyunBAyig5i5jCebcFNelfbPS TxOBSjatodhSTL4/t+x9YkZ6ZYeQal3+RteD7wwPm9J119AXS9yUtwP8bgABrDB5/9wG H9Gw== X-Gm-Message-State: AHQUAuYapS044bVjgJXdkb9r7vVtgLnZEx62Jg+f0omTD44yFd0htgAS 39ZVigoQqdkQZc+XEFT2L3o= X-Google-Smtp-Source: AHgI3IYc+gpPdAGLkHYYG31vqJed8SLr64mBh37V5iqHL5UH0HjSBMvMZvWjQ8PWA4SAOmnETK7eWA== X-Received: by 2002:a62:ca03:: with SMTP id n3mr5255803pfg.241.1549994839828; Tue, 12 Feb 2019 10:07:19 -0800 (PST) Received: from localhost.localdomain ([43.224.245.179]) by smtp.gmail.com with ESMTPSA id u5sm16857510pgp.2.2019.02.12.10.07.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 12 Feb 2019 10:07:19 -0800 (PST) From: Xiang Xiao X-Google-Original-From: Xiang Xiao To: gregkh@linuxfoundation.org, alexander.shishkin@linux.intel.com, andriy.shevchenko@linux.intel.com, linux-kernel@vger.kernel.org Cc: Xiang Xiao Subject: [PATCH] lib/string: add memrchr function Date: Wed, 13 Feb 2019 02:06:49 +0800 Message-Id: <1549994809-27479-1-git-send-email-xiaoxiang@xiaomi.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Here is the detailed description for memrchr: https://linux.die.net/man/3/memrchr Signed-off-by: Xiang Xiao --- include/linux/string.h | 1 + lib/string.c | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/include/linux/string.h b/include/linux/string.h index 7927b87..f380f4b 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -167,6 +167,7 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt) memcpy(dst, src, cnt); } #endif +void *memrchr(const void *s, int c, size_t n); void *memchr_inv(const void *s, int c, size_t n); char *strreplace(char *s, char old, char new); diff --git a/lib/string.c b/lib/string.c index 38e4ca0..92914f6 100644 --- a/lib/string.c +++ b/lib/string.c @@ -964,6 +964,27 @@ void *memchr(const void *s, int c, size_t n) EXPORT_SYMBOL(memchr); #endif +/** + * memrchr - Find a character in an area of memory. + * @s: The memory area + * @c: The byte to search for + * @n: The size of the area. + * + * returns the address of the last occurrence of @c, or %NULL + * if @c is not found + */ +void *memrchr(const void *s, int c, size_t n) +{ + const unsigned char *p = s + n; + + while (n-- != 0) { + if ((unsigned char)c == *--p) + return (void *)p; + } + return NULL; +} +EXPORT_SYMBOL(memrchr); + static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) { while (bytes) { -- 2.7.4