From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Subject: [PATCH] dm raid1: Use struct_size() in kzalloc() Date: Mon, 5 Aug 2019 19:18:25 -0500 Message-ID: <20190806001825.GA6854@embeddedor> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Alasdair Kergon , Mike Snitzer Cc: dm-devel@redhat.com, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" List-Id: dm-devel.ids 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 mirror_set { ... struct mirror mirror[0]; }; size = sizeof(struct mirror_set) + count * sizeof(struct mirror); instance = kzalloc(size, GFP_KERNEL) Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kzalloc(struct_size(instance, mirror, count), GFP_KERNEL) Notice that, in this case, variable len is not necessary, hence it is removed. This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva --- drivers/md/dm-raid1.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index 5a51151f680d..f7226ab57fc8 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -878,12 +878,9 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors, struct dm_target *ti, struct dm_dirty_log *dl) { - size_t len; struct mirror_set *ms = NULL; - len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors); - - ms = kzalloc(len, GFP_KERNEL); + ms = kzalloc(struct_size(ms, mirror, nr_mirrors), GFP_KERNEL); if (!ms) { ti->error = "Cannot allocate mirror context"; return NULL; -- 2.22.0