[PATCH][next] netronome: Replace zero-length array with flexible-array member
From: Gustavo A. R. Silva <hidden>
Date: 2020-02-24 16:34:08
Also in:
bpf, lkml
Subsystem:
bpf jit for nfp nics, netronome ethernet drivers, networking drivers, the rest · Maintainers:
Jakub Kicinski, Andrew Lunn, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
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 <redacted>
---
drivers/net/ethernet/netronome/nfp/bpf/fw.h | 6 +++---
drivers/net/ethernet/netronome/nfp/flower/cmsg.h | 4 ++--
drivers/net/ethernet/netronome/nfp/nfp_main.h | 2 +-
drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c | 8 ++++----
drivers/net/ethernet/netronome/nfp/nfp_net_repr.h | 2 +-
drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h | 2 +-
6 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/fw.h b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
index a83a0ad5e27d..4268a7e0f344 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/fw.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/fw.h@@ -104,14 +104,14 @@ struct cmsg_req_map_op { __be32 tid; __be32 count; __be32 flags; - u8 data[0]; + u8 data[]; }; struct cmsg_reply_map_op { struct cmsg_reply_map_simple reply_hdr; __be32 count; __be32 resv; - u8 data[0]; + u8 data[]; }; struct cmsg_bpf_event {
@@ -120,6 +120,6 @@ struct cmsg_bpf_event { __be64 map_ptr; __be32 data_size; __be32 pkt_size; - u8 data[0]; + u8 data[]; }; #endif
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 {
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_main.h b/drivers/net/ethernet/netronome/nfp/nfp_main.h
index 5d5812fd9317..fa6b13a05941 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_main.h
+++ b/drivers/net/ethernet/netronome/nfp/nfp_main.h@@ -42,7 +42,7 @@ struct nfp_shared_buf; */ struct nfp_dumpspec { u32 size; - u8 data[0]; + u8 data[]; }; /**
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c b/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c
index 769ceef09756..a614df095b08 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c@@ -36,7 +36,7 @@ enum nfp_dumpspec_type { struct nfp_dump_tl { __be32 type; __be32 length; /* chunk length to follow, aligned to 8 bytes */ - char data[0]; + char data[]; }; /* NFP CPP parameters */
@@ -62,7 +62,7 @@ struct nfp_dumpspec_csr { struct nfp_dumpspec_rtsym { struct nfp_dump_tl tl; - char rtsym[0]; + char rtsym[]; }; /* header for register dumpable */
@@ -79,7 +79,7 @@ struct nfp_dump_rtsym { struct nfp_dump_common_cpp cpp; __be32 error; /* error code encountered while reading */ u8 padded_name_length; /* pad so data starts at 8 byte boundary */ - char rtsym[0]; + char rtsym[]; /* after padded_name_length, there is dump_length data */ };
@@ -92,7 +92,7 @@ struct nfp_dump_error { struct nfp_dump_tl tl; __be32 error; char padding[4]; - char spec[0]; + char spec[]; }; /* to track state through debug size calculation TLV traversal */
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h
index e0f13dfe1f39..48a74accbbd3 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h@@ -18,7 +18,7 @@ struct nfp_port; */ struct nfp_reprs { unsigned int num_reprs; - struct net_device __rcu *reprs[0]; + struct net_device __rcu *reprs[]; }; /**
diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h
index 1531c1870020..f5360bae6f75 100644
--- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h
+++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h@@ -183,7 +183,7 @@ struct nfp_eth_table { bool is_split; unsigned int fec_modes_supported; - } ports[0]; + } ports[]; }; struct nfp_eth_table *nfp_eth_read_ports(struct nfp_cpp *cpp);
--
2.25.0