On Fri, Dec 12, 2025 at 03:44:50PM +0900, Gustavo A. R. Silva wrote:
> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
> getting ready to enable it, globally.
>
> Use the new __TRAILING_OVERLAP() helper to fix the following warning:
>
> include/hyperv/hvgdk_mini.h:581:25: warning: structure containing a flexible
> array member is not at the end of another structure
> [-Wflex-array-member-not-at-end]
>
> This helper creates a union between a flexible-array member (FAM) and a
> set of MEMBERS that would otherwise follow it.
>
> This overlays the trailing MEMBER u64 gva_list[]; onto the FAM
> struct hv_tlb_flush_ex::hv_vp_set.bank_contents[], while keeping
> the FAM and the start of MEMBER aligned.
>
> The static_assert() ensures this alignment remains, and it's
> intentionally placed inmediately after the related structure --no
> blank line in between.
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
Applied. I fixed a typo in the commit message ("inmediately" ->
"immediately").
Wei
> ---
> include/hyperv/hvgdk_mini.h | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
> index 04b18d0e37af..30fbbde81c5c 100644
> --- a/include/hyperv/hvgdk_mini.h
> +++ b/include/hyperv/hvgdk_mini.h
> @@ -578,9 +578,12 @@ struct hv_tlb_flush { /*
> HV_INPUT_FLUSH_VIRTUAL_ADDRESS_LIST */
> struct hv_tlb_flush_ex {
> u64 address_space;
> u64 flags;
> - struct hv_vpset hv_vp_set;
> - u64 gva_list[];
> + __TRAILING_OVERLAP(struct hv_vpset, hv_vp_set, bank_contents, __packed,
> + u64 gva_list[];
> + );
> } __packed;
> +static_assert(offsetof(struct hv_tlb_flush_ex, hv_vp_set.bank_contents) ==
> + offsetof(struct hv_tlb_flush_ex, gva_list));
>
> struct ms_hyperv_tsc_page { /* HV_REFERENCE_TSC_PAGE */
> volatile u32 tsc_sequence;
> --
> 2.43.0
>
