From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Thu, 7 Feb 2019 22:15:40 -0600
Subject: igb: use struct_size() helper
Patch-mainline: v5.1-rc1
Git-commit: a0feac18b8b590d9b588b4285841bac7c372fd8b
References: jsc#SLE-4798

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[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/igb/igb_main.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -1209,15 +1209,15 @@ static int igb_alloc_q_vector(struct igb
 {
 	struct igb_q_vector *q_vector;
 	struct igb_ring *ring;
-	int ring_count, size;
+	int ring_count;
+	size_t size;
 
 	/* igb only supports 1 Tx and/or 1 Rx queue per vector */
 	if (txr_count > 1 || rxr_count > 1)
 		return -ENOMEM;
 
 	ring_count = txr_count + rxr_count;
-	size = sizeof(struct igb_q_vector) +
-	       (sizeof(struct igb_ring) * ring_count);
+	size = struct_size(q_vector, ring, ring_count);
 
 	/* allocate q_vector and rings */
 	q_vector = adapter->q_vector[v_idx];