[PATCH net-next] cxgb4: clip_tbl: Use struct_size() in kvzalloc()

Gustavo A. R. Silva
2019-01-29T16:44:57Z

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.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c b/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c
index 5701272aa7f7..ce28820c57c9 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c
@@ -289,8 +289,7 @@ struct clip_tbl *t4_init_clip_tbl(unsigned int clipt_start,
if (clipt_size < CLIPT_MIN_HASH_BUCKETS)
return NULL;

- ctbl = kvzalloc(sizeof(*ctbl) +
- clipt_size*sizeof(struct list_head), GFP_KERNEL);
+ ctbl = kvzalloc(struct_size(ctbl, hash_list, clipt_size), GFP_KERNEL);
if (!ctbl)
return NULL;

--
2.20.1