From 5b361328ca649534d721e4eae20c96ccbe702ce7 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 12 Feb 2020 19:04:25 -0600 Subject: RDMA: 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") Link: https://lore.kernel.org/r/20200213010425.GA13068@embeddedor.com Signed-off-by: Gustavo A. R. Silva Signed-off-by: Jason Gunthorpe # added a few more --- drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/infiniband/ulp/opa_vnic') diff --git a/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h b/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h index 4480092c68e0..0b3570dc606d 100644 --- a/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h +++ b/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h @@ -258,7 +258,7 @@ struct opa_veswport_mactable { __be16 offset; __be16 num_entries; __be32 mac_tbl_digest; - struct opa_veswport_mactable_entry tbl_entries[0]; + struct opa_veswport_mactable_entry tbl_entries[]; } __packed; /** @@ -440,7 +440,7 @@ struct opa_veswport_iface_macs { __be16 num_macs_in_msg; __be16 tot_macs_in_lst; __be16 gen_count; - struct opa_vnic_iface_mac_entry entry[0]; + struct opa_vnic_iface_mac_entry entry[]; } __packed; /** -- cgit v1.2.3