cxgb4: smt: 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/smt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index 7b2207a2a130..eaf1fb74689c 100644
@@ -47,8 +47,7 @@ struct smt_data *t4_init_smt(void)
 
 	smt_size = SMT_SIZE;
 
-	s = kvzalloc(sizeof(*s) + smt_size * sizeof(struct smt_entry),
-		     GFP_KERNEL);
+	s = kvzalloc(struct_size(s, smtab, smt_size), GFP_KERNEL);
 	if (!s)
 		return NULL;
 	s->smt_size = smt_size;

2.20.1

From: "Gustavo A. R. Silva" <[email protected]>
Date: Wed, 30 Jan 2019 18:27:44 -0600

Applied.