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 <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 4 deletions

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 */