diff options
authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 13:59:21 -0500
committerJakub Kicinski <kuba@kernel.org>2020-05-09 20:49:13 -0700
commite7bb7ecefa817543e11fa3c1c3e55deb90b02e6c (patch)
parentMerge branch 'mlxsw-spectrum-Enforce-some-HW-limitations-for-matchall-TC-offload' (diff)
IB/mlx4: Replace zero-length array with flexible-array
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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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 <gustavoars@kernel.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mlx4/qp.h b/include/linux/mlx4/qp.h
index 8e2828d48d7f..9db93e487496 100644
--- a/include/linux/mlx4/qp.h
+++ b/include/linux/mlx4/qp.h
@@ -362,7 +362,7 @@ struct mlx4_wqe_datagram_seg {
struct mlx4_wqe_lso_seg {
__be32 mss_hdr_size;
- __be32 header[0];
+ __be32 header[];
enum mlx4_wqe_bind_seg_flags2 {