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=-18.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 6C8B9C433E0 for ; Wed, 29 Jul 2020 14:50:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4CD6B20809 for ; Wed, 29 Jul 2020 14:50:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Uekz1hDH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726869AbgG2OuW (ORCPT ); Wed, 29 Jul 2020 10:50:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34784 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726385AbgG2OuV (ORCPT ); Wed, 29 Jul 2020 10:50:21 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DFB9C061794 for ; Wed, 29 Jul 2020 07:50:21 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id mt12so1967837pjb.4 for ; Wed, 29 Jul 2020 07:50:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=XgDzWs5LYt7Mkx0UdbPr7BFgEZ8N/ZoZ6ADwKcHkW84=; b=Uekz1hDHFE/A9esJhBdVFwm8ohWCgO/OY+8PRW1Bp2rQOpEMNN1vlmW+8ay2DT91cC 7eD39VYxARUX7FoPwiGCEGuKIqd7uzQ0yuRdRsUhVuy+XVqUoytulRJDXGOkjnpk4WIQ /F5R0wumaXINUq/XwS3HWxK+YZttG/FXg/eyuOPSQXavDsp4DE6hVWijJQRb/+g8uEm+ L8z4RGzDZwAonZa3lTaSb5tla73JNC4esECyEUnIvyakAruIZnKlTUP1hUtcwhuosDWz 7kVUbvMUh33slesyNHfEwPykMehktJmKvc8qgzggibg4jyM5K4SDzXd5fhQXDd+zKHKL MG3Q== 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:mime-version :content-transfer-encoding; bh=XgDzWs5LYt7Mkx0UdbPr7BFgEZ8N/ZoZ6ADwKcHkW84=; b=hMalOlnqSm1AGmuo+n9JI+BuoxRH99aSqtIZfduslftazpdWoRSfRcZrTepg3LpRXy vVs5z/ScXOKxGMiJxc6uoOJOdaz/1fE8ZFeZv0VrrlOyrmLi4I/MlFQnYRX3glKXbMQW igz1q+OA7LNcnvQ23ynYsS7OsO5OH96oNSd07pAZbiE5QXmcHKl09fkGiWi12eEL2UkZ uV37ZaSUEPDVw7/mx0YJ1dkbK94St3rkhY8PSN0+sFZjh/h0bO81OR58V2XXnTn6ishS ajpbzoq7Zu4H6G2DjuWlv/p4f0r5nYZo90unK7tnbRdtpg94ZJXq/13GMegio81Tuc94 UYEA== X-Gm-Message-State: AOAM532p+9enxRPWQtif86vbQFvyv5DU9aFpyyJD18dOaX+fimnpofyL 5My1tbK5mYks8NOJAOXjhW0= X-Google-Smtp-Source: ABdhPJxsckiyS9HZ6KWrI4D+jRealIDAmq6K3fsnqkoDoBrRPnfto+1PgdXkVPNlSwxO859eW7X4jQ== X-Received: by 2002:a17:902:d303:: with SMTP id b3mr13162508plc.101.1596034220591; Wed, 29 Jul 2020 07:50:20 -0700 (PDT) Received: from builder-PowerEdge-R730xd.mioffice.cn ([43.224.245.179]) by smtp.gmail.com with ESMTPSA id o190sm1251827pfd.194.2020.07.29.07.50.17 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 29 Jul 2020 07:50:20 -0700 (PDT) From: Qianli Zhao To: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, zhaoqianli@xiaomi.com Subject: [PATCH] mm: slab: Avoid the use of one-element array and use struct_size() helper Date: Wed, 29 Jul 2020 22:50:14 +0800 Message-Id: <1596034214-15010-1-git-send-email-zhaoqianligood@gmail.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qianli Zhao There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. Make use of the struct_size() helper instead of an open-coded version in order to avoid any potential type mistakes. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://github.com/KSPP/linux/issues/21 Signed-off-by: Qianli Zhao --- mm/slab.h | 2 +- mm/slab_common.c | 7 ++----- 2 files changed, 3 insertions(+), 6 deletions(-) diff --git a/mm/slab.h b/mm/slab.h index 74f7e09..c12fb65 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -34,7 +34,7 @@ struct kmem_cache { struct memcg_cache_array { struct rcu_head rcu; - struct kmem_cache *entries[0]; + struct kmem_cache *entries[]; }; /* diff --git a/mm/slab_common.c b/mm/slab_common.c index fe8b684..56f4818 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -166,9 +166,7 @@ static int init_memcg_params(struct kmem_cache *s, if (!memcg_nr_cache_ids) return 0; - arr = kvzalloc(sizeof(struct memcg_cache_array) + - memcg_nr_cache_ids * sizeof(void *), - GFP_KERNEL); + arr = kvzalloc(struct_size(arr, entries, memcg_nr_cache_ids), GFP_KERNEL); if (!arr) return -ENOMEM; @@ -199,8 +197,7 @@ static int update_memcg_params(struct kmem_cache *s, int new_array_size) { struct memcg_cache_array *old, *new; - new = kvzalloc(sizeof(struct memcg_cache_array) + - new_array_size * sizeof(void *), GFP_KERNEL); + new = kvzalloc(struct_size(new, entries, new_array_size), GFP_KERNEL); if (!new) return -ENOMEM; -- 2.7.4