[PATCH] md-linear: use struct_size() in kzalloc()

From: Gustavo A. R. Silva
Date: Mon Jan 07 2019 - 12:45:43 EST

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;
void *entry[];

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
drivers/md/md-linear.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
index d45c697c0ebe..5998d78aa189 100644
--- a/drivers/md/md-linear.c
+++ b/drivers/md/md-linear.c
@@ -96,8 +96,7 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
int i, cnt;
bool discard_supported = false;

- conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
+ conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
if (!conf)
return NULL;