linux/drivers/infiniband/sw
Gustavo A. R. Silva 5b361328ca 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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Link: https://lore.kernel.org/r/20200213010425.GA13068@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> # added a few more
2020-02-20 13:33:51 -04:00
..
rdmavt Use ODP MRs for kernel ULPs 2020-01-21 09:55:04 -04:00
rxe RDMA: Replace zero-length array with flexible-array member 2020-02-20 13:33:51 -04:00
siw RDMA/siw: Fix setting active_mtu attribute 2020-02-11 14:32:35 -04:00
Makefile rdma/siw: addition to kernel build environment 2019-07-02 17:03:41 -03:00