igb: use struct_size() helper

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>

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 6d812e9..69b230c 100644 (file)
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -1189,15 +1189,15 @@ static int igb_alloc_q_vector(struct igb_adapter *adapter,
 {
        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];