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net/mlx5e: Replace zero-length array with flexible-array member 

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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
This commit is contained in:
Gustavo A. R. Silva 2020-02-18 14:31:14 -06:00 committed by Leon Romanovsky
parent d8fab4815a
commit 339ffae598
4 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/ethernet/mellanox/mlx5/core/en.h
View File

@ -204,7 +204,7 @@ struct mlx5e_tx_wqe {
struct mlx5e_rx_wqe_ll {
struct mlx5_wqe_srq_next_seg next;
struct mlx5_wqe_data_seg data[0];
struct mlx5_wqe_data_seg data[];
};
struct mlx5e_rx_wqe_cyc {

2
drivers/net/ethernet/mellanox/mlx5/core/fpga/ipsec.c
View File

@ -57,7 +57,7 @@ struct mlx5_fpga_ipsec_cmd_context {
struct completion complete;
struct mlx5_fpga_device *dev;
struct list_head list; /* Item in pending_cmds */
u8 command[0];
u8 command[];
};
struct mlx5_fpga_esp_xfrm;

2
drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c
View File

@ -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,

4
drivers/net/ethernet/mellanox/mlx5/core/ipoib/ipoib.h
View File

@ -56,7 +56,7 @@ struct mlx5i_priv {
u32 qkey;
u16 pkey_index;
struct mlx5i_pkey_qpn_ht *qpn_htbl;
char *mlx5e_priv[0];
char *mlx5e_priv[];
};
int mlx5i_create_tis(struct mlx5_core_dev *mdev, u32 underlay_qpn, u32 *tisn);
@ -107,7 +107,7 @@ struct mlx5i_tx_wqe {
struct mlx5_wqe_datagram_seg datagram;
struct mlx5_wqe_eth_pad pad;
struct mlx5_wqe_eth_seg eth;
struct mlx5_wqe_data_seg data[0];
struct mlx5_wqe_data_seg data[];
};
static inline void mlx5i_sq_fetch_wqe(struct mlx5e_txqsq *sq,