From 3f6e963305d4ea8f37cdbc614e7a23466ef24013 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 10:36:52 -0600 Subject: netronome: 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller --- drivers/net/ethernet/netronome/nfp/flower/cmsg.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/net/ethernet/netronome/nfp/flower') diff --git a/drivers/net/ethernet/netronome/nfp/flower/cmsg.h b/drivers/net/ethernet/netronome/nfp/flower/cmsg.h index 9b50d76bbc09..bf516285510f 100644 --- a/drivers/net/ethernet/netronome/nfp/flower/cmsg.h +++ b/drivers/net/ethernet/netronome/nfp/flower/cmsg.h @@ -587,7 +587,7 @@ struct nfp_flower_cmsg_mac_repr { u8 info; u8 nbi_port; u8 phys_port; - } ports[0]; + } ports[]; }; #define NFP_FLOWER_CMSG_MAC_REPR_NBI GENMASK(1, 0) @@ -619,7 +619,7 @@ struct nfp_flower_cmsg_merge_hint { struct { __be32 host_ctx; __be64 host_cookie; - } __packed flow[0]; + } __packed flow[]; }; enum nfp_flower_cmsg_port_type { -- cgit v1.2.3