Messages in this thread Patch in this message | | | Date | Mon, 24 Feb 2020 10:43:46 -0600 | From | "Gustavo A. R. Silva" <> | Subject | [PATCH][next] freescale: Replace zero-length array with flexible-array member |
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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/freescale/enetc/enetc.h | 2 +- drivers/net/ethernet/freescale/enetc/enetc_hw.h | 2 +- drivers/net/ethernet/freescale/fec.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.h b/drivers/net/ethernet/freescale/enetc/enetc.h index dd4a227ffc7a..9938f7a5fc0a 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc.h +++ b/drivers/net/ethernet/freescale/enetc/enetc.h @@ -163,7 +163,7 @@ struct enetc_int_vector { char name[ENETC_INT_NAME_MAX]; struct enetc_bdr rx_ring ____cacheline_aligned_in_smp; - struct enetc_bdr tx_ring[0]; + struct enetc_bdr tx_ring[]; }; struct enetc_cls_rule { diff --git a/drivers/net/ethernet/freescale/enetc/enetc_hw.h b/drivers/net/ethernet/freescale/enetc/enetc_hw.h index 62554f28ce07..da134e211c1a 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc_hw.h +++ b/drivers/net/ethernet/freescale/enetc/enetc_hw.h @@ -588,7 +588,7 @@ struct tgs_gcl_data { __le32 bth; __le32 ct; __le32 cte; - struct gce entry[0]; + struct gce entry[]; }; struct enetc_cbd { diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h index f79e57f735b3..bd898f5b4da5 100644 --- a/drivers/net/ethernet/freescale/fec.h +++ b/drivers/net/ethernet/freescale/fec.h @@ -584,7 +584,7 @@ struct fec_enet_private { int pps_enable; unsigned int next_counter; - u64 ethtool_stats[0]; + u64 ethtool_stats[]; }; void fec_ptp_init(struct platform_device *pdev, int irq_idx); -- 2.25.0
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