diff options
authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-28 07:19:07 -0600
committerDavid S. Miller <davem@davemloft.net>2020-02-28 12:08:37 -0800
commit95e486f5519848ca4c2f2645cbe120de5df133f3 (patch)
parent549da33801266c6cb04431add7c205bb43e93acf (diff)
xdp: 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> Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com> Acked-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 2 insertions, 2 deletions
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 89a01ac4e079..b50bb5c76da5 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -19,13 +19,13 @@ struct xdp_ring {
/* Used for the RX and TX queues for packets */
struct xdp_rxtx_ring {
struct xdp_ring ptrs;
- struct xdp_desc desc[0] ____cacheline_aligned_in_smp;
+ struct xdp_desc desc[] ____cacheline_aligned_in_smp;
/* Used for the fill and completion queues for buffers */
struct xdp_umem_ring {
struct xdp_ring ptrs;
- u64 desc[0] ____cacheline_aligned_in_smp;
+ u64 desc[] ____cacheline_aligned_in_smp;
struct xsk_queue {