cxgb4/l2t: Use struct_size() in kvzalloc()

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[];
};

instance = kvzalloc(sizeof(struct foo) + count * sizeof(struct boo), 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);

This code was detected with the help of Coccinelle.

---
 drivers/net/ethernet/chelsio/cxgb4/l2t.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 4852febbfec3..1a407d3c1d67 100644
@@ -646,7 +646,7 @@ struct l2t_data *t4_init_l2t(unsigned int l2t_start, unsigned int l2t_end)
 	if (l2t_size < L2T_MIN_HASH_BUCKETS)
 		return NULL;
 
-	d = kvzalloc(sizeof(*d) + l2t_size * sizeof(struct l2t_entry), GFP_KERNEL);
+	d = kvzalloc(struct_size(d, l2tab, l2t_size), GFP_KERNEL);
 	if (!d)
 		return NULL;
 

2.20.1

From: "Gustavo A. R. Silva" <[email protected]>
Date: Tue, 15 Jan 2019 15:44:52 -0600

Applied.