[PATCH net-next] mlxsw: spectrum_acl_bloom_filter: use struct_size() in kzalloc()

From: Gustavo A. R. Silva
Date: Tue Jan 15 2019 - 18:05:44 EST


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[];
};

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

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

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
.../net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
index 505b87846acc..f5c381dcb015 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
@@ -234,8 +234,8 @@ mlxsw_sp_acl_bf_init(struct mlxsw_sp *mlxsw_sp, unsigned int num_erp_banks)
* is 2^ACL_MAX_BF_LOG
*/
bf_bank_size = 1 << MLXSW_CORE_RES_GET(mlxsw_sp->core, ACL_MAX_BF_LOG);
- bf = kzalloc(sizeof(*bf) + bf_bank_size * num_erp_banks *
- sizeof(*bf->refcnt), GFP_KERNEL);
+ bf = kzalloc(struct_size(bf, refcnt, bf_bank_size * num_erp_banks),
+ GFP_KERNEL);
if (!bf)
return ERR_PTR(-ENOMEM);

--
2.17.0