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[192.185.150.24]) by mx.google.com with ESMTPS id n7si9311699oif.113.2019.02.21.07.46.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 21 Feb 2019 07:46:24 -0800 (PST) Received-SPF: softfail (google.com: domain of transitioning gustavo@embeddedor.com does not designate 192.185.150.24 as permitted sender) client-ip=192.185.150.24; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gustavo@embeddedor.com does not designate 192.185.150.24 as permitted sender) smtp.mailfrom=gustavo@embeddedor.com Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 06B2B3242E for ; Thu, 21 Feb 2019 09:46:24 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id wqYJg4FK290onwqYJgPvga; Thu, 21 Feb 2019 09:46:24 -0600 X-Authority-Reason: nr=8 Received: from [189.250.119.20] (port=37372 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1gwqYJ-000atD-5u; Thu, 21 Feb 2019 09:46:23 -0600 Date: Thu, 21 Feb 2019 09:46:22 -0600 From: "Gustavo A. R. Silva" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] mm/swapfile.c: use struct_size() in kvzalloc() Message-ID: <20190221154622.GA19599@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - kvack.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 189.250.119.20 X-Source-L: No X-Exim-ID: 1gwqYJ-000atD-5u X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [189.250.119.20]:37372 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 19 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct foo { int stuff; struct boo entry[]; }; size = sizeof(struct foo) + count * sizeof(struct boo); instance = kvzalloc(size, GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kvzalloc(struct_size(instance, entry, count), GFP_KERNEL); Notice that, in this case, variable size is not necessary, hence it is removed. This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva --- mm/swapfile.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index cca8420b12db..fd9b0025ad00 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2713,9 +2713,8 @@ static struct swap_info_struct *alloc_swap_info(void) struct swap_info_struct *p; unsigned int type; int i; - unsigned int size = sizeof(*p) + nr_node_ids * sizeof(struct plist_node); - p = kvzalloc(size, GFP_KERNEL); + p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); if (!p) return ERR_PTR(-ENOMEM);