[PATCH net-next] wimax/i2400m: use struct_size() helper

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

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[];
};

size = sizeof(struct foo) + count * sizeof(void *);
instance = alloc(size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

size = struct_size(instance, entry, count);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/wimax/i2400m/rx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wimax/i2400m/rx.c b/drivers/net/wimax/i2400m/rx.c
index 0b602951ff6b..d28b96d06919 100644
--- a/drivers/net/wimax/i2400m/rx.c
+++ b/drivers/net/wimax/i2400m/rx.c
@@ -1260,8 +1260,8 @@ int i2400m_rx(struct i2400m *i2400m, struct sk_buff *skb)
 		goto error_msg_hdr_check;
 	result = -EIO;
 	num_pls = le16_to_cpu(msg_hdr->num_pls);
-	pl_itr = sizeof(*msg_hdr) +	/* Check payload descriptor(s) */
-		num_pls * sizeof(msg_hdr->pld[0]);
+	/* Check payload descriptor(s) */
+	pl_itr = struct_size(msg_hdr, pld, num_pls);
 	pl_itr = ALIGN(pl_itr, I2400M_PL_ALIGN);
 	if (pl_itr > skb_len) {	/* got all the payload descriptors? */
 		dev_err(dev, "RX: HW BUG? message too short (%u bytes) for "
-- 
2.20.1