linux/drivers/net/ethernet/netronome/nfp/bpf
Gustavo A. R. Silva 3f6e963305 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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-24 15:26:17 -08:00
..
cmsg.c nfp: bpf: add simple map op cache 2019-08-31 00:49:05 +02:00
fw.h netronome: Replace zero-length array with flexible-array member 2020-02-24 15:26:17 -08:00
jit.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
main.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
main.h nfp: bpf: add simple map op cache 2019-08-31 00:49:05 +02:00
offload.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
verifier.c nfp: bpf: eliminate zero extension code-gen 2019-05-24 18:58:38 -07:00