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net/mlx4_en: Replace fake flex-array with flexible-array member

PATCH In review Gustavo A. R. Silva 2 participants 2 messages Mar 6, 2023 – Mar 7, 2023

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Networking Network drivers InfiniBand Mellanox MLX4 core VPI driver
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Gustavo A. R. Silva

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PATCH 1/1 net/mlx4_en: Replace fake flex-array with flexible-array member

Zero-length arrays as fake flexible arrays are deprecated and we are moving towards adopting C99 flexible-array members instead.

Transform zero-length array into flexible-array member in struct mlx4_en_rx_desc.

Address the following warnings found with GCC-13 and
-fstrict-flex-arrays=3 enabled:
drivers/net/ethernet/mellanox/mlx4/en_rx.c:88:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:149:30: warning: array subscript 0 is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:127:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:128:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:129:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:117:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:119:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines on memcpy() and help us make progress towards globally enabling -fstrict-flex-arrays=3 [1].

Link https://github.com/KSPP/linux/issues/21
Link https://github.com/KSPP/linux/issues/264
Link https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +1 -1
index 544e09b97483..034733b13b1a 100644
@@ -323,7 +323,7 @@ struct mlx4_en_tx_ring {
 
 struct mlx4_en_rx_desc {
 	/* actual number of entries depends on rx ring stride */
-	struct mlx4_wqe_data_seg data[0];
+	DECLARE_FLEX_ARRAY(struct mlx4_wqe_data_seg, data);
 };
 
 struct mlx4_en_rx_ring {
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 33 lines · Gustavo A. R. Silva

Zero-length arrays as fake flexible arrays are deprecated and we are moving towards adopting C99 flexible-array members instead.

Transform zero-length array into flexible-array member in struct mlx4_en_rx_desc.

Address the following warnings found with GCC-13 and
-fstrict-flex-arrays=3 enabled:
drivers/net/ethernet/mellanox/mlx4/en_rx.c:88:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:149:30: warning: array subscript 0 is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:127:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:128:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:129:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:117:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=] drivers/net/ethernet/mellanox/mlx4/en_rx.c:119:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines on memcpy() and help us make progress towards globally enabling -fstrict-flex-arrays=3 [1].

Link https://github.com/KSPP/linux/issues/21
Link https://github.com/KSPP/linux/issues/264
Link https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
  drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +0 -0
index 544e09b97483..034733b13b1a 100644

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h struct mlx4_en_tx_ring { · line 329

Quoted 8 lines
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +1 -1
@@ -323,7 +323,7 @@ struct mlx4_en_tx_ring {
 
  struct mlx4_en_rx_desc {
  	/* actual number of entries depends on rx ring stride */
-	struct mlx4_wqe_data_seg data[0];
+	DECLARE_FLEX_ARRAY(struct mlx4_wqe_data_seg, data);
  };
 
  struct mlx4_en_rx_ring {
Reviewed-by Tariq Toukan <[email protected]>

Thanks for your patch.