| Message ID | 20200217195639.GA2097@embeddedor (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [next] net/mlx5/fs_counters: Replace zero-length array with flexible-array member | expand |
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c index ab69effb056d..f43caefd07a1 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c @@ -470,7 +470,7 @@ struct mlx5_fc_bulk { u32 base_id; int bulk_len; unsigned long *bitmask; - struct mlx5_fc fcs[0]; + struct mlx5_fc fcs[]; }; static void mlx5_fc_init(struct mlx5_fc *counter, struct mlx5_fc_bulk *bulk,
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)