From bcd676542cdd44b3a91e0b695cc1d7a1d35679cd Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 5 Aug 2019 19:18:25 -0500 Subject: [PATCH] dm raid1: use struct_size() with kzalloc() 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 Signed-off-by: Mike Snitzer --- drivers/md/dm-raid1.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index 5a51151f680d..089aed57e083 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; + struct mirror_set *ms = + kzalloc(struct_size(ms, mirror, nr_mirrors), GFP_KERNEL); - len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors); - - ms = kzalloc(len, GFP_KERNEL); if (!ms) { ti->error = "Cannot allocate mirror context"; return NULL;