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Subject[PATCH net-next] 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>
---
drivers/net/ethernet/intel/igb/igb_main.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 6d812e96572d..69b230c53fed 100644
--- 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];
--
2.20.1
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