Re: [PATCH] KVM: selftests: Fix compiling errors when initializing the static structure

[Paolo Bonzini]

On 10/06/21 10:54, Yanan Wang wrote:
> Errors like below were produced from test_util.c when compiling the KVM
> selftests on my local platform.
>
> lib/test_util.c: In function 'vm_mem_backing_src_alias':
> lib/test_util.c:177:12: error: initializer element is not constant
>      .flag = anon_flags,
>              ^~~~~~~~~~
> lib/test_util.c:177:12: note: (near initialization for 'aliases[0].flag')
>
> The reason is that we are using non-const expressions to initialize the
> static structure, which will probably trigger a compiling error/warning
> on stricter GCC versions. Fix it by converting the two const variables
> "anon_flags" and "anon_huge_flags" into more stable macros.
>
> Fixes: b3784bc28ccc0 ("KVM: selftests: refactor vm_mem_backing_src_type flags")
> Reported-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>
> Signed-off-by: Yanan Wang <wangyanan55@xxxxxxxxxx>
> ---
>   tools/testing/selftests/kvm/lib/test_util.c | 38 ++++++++++-----------
>   1 file changed, 19 insertions(+), 19 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index 6ad6c8276b2e..af1031fed97f 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -166,75 +166,75 @@ size_t get_def_hugetlb_pagesz(void)
>   	return 0;
>   }
>   
> +#define ANON_FLAGS	(MAP_PRIVATE | MAP_ANONYMOUS)
> +#define ANON_HUGE_FLAGS	(ANON_FLAGS | MAP_HUGETLB)
> +
>   const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i)
>   {
> -	static const int anon_flags = MAP_PRIVATE | MAP_ANONYMOUS;
> -	static const int anon_huge_flags = anon_flags | MAP_HUGETLB;
> -
>   	static const struct vm_mem_backing_src_alias aliases[] = {
>   		[VM_MEM_SRC_ANONYMOUS] = {
>   			.name = "anonymous",
> -			.flag = anon_flags,
> +			.flag = ANON_FLAGS,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_THP] = {
>   			.name = "anonymous_thp",
> -			.flag = anon_flags,
> +			.flag = ANON_FLAGS,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB] = {
>   			.name = "anonymous_hugetlb",
> -			.flag = anon_huge_flags,
> +			.flag = ANON_HUGE_FLAGS,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_16KB] = {
>   			.name = "anonymous_hugetlb_16kb",
> -			.flag = anon_huge_flags | MAP_HUGE_16KB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_16KB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_64KB] = {
>   			.name = "anonymous_hugetlb_64kb",
> -			.flag = anon_huge_flags | MAP_HUGE_64KB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_64KB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_512KB] = {
>   			.name = "anonymous_hugetlb_512kb",
> -			.flag = anon_huge_flags | MAP_HUGE_512KB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_512KB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_1MB] = {
>   			.name = "anonymous_hugetlb_1mb",
> -			.flag = anon_huge_flags | MAP_HUGE_1MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_1MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_2MB] = {
>   			.name = "anonymous_hugetlb_2mb",
> -			.flag = anon_huge_flags | MAP_HUGE_2MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_2MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_8MB] = {
>   			.name = "anonymous_hugetlb_8mb",
> -			.flag = anon_huge_flags | MAP_HUGE_8MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_8MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_16MB] = {
>   			.name = "anonymous_hugetlb_16mb",
> -			.flag = anon_huge_flags | MAP_HUGE_16MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_16MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_32MB] = {
>   			.name = "anonymous_hugetlb_32mb",
> -			.flag = anon_huge_flags | MAP_HUGE_32MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_32MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_256MB] = {
>   			.name = "anonymous_hugetlb_256mb",
> -			.flag = anon_huge_flags | MAP_HUGE_256MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_256MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_512MB] = {
>   			.name = "anonymous_hugetlb_512mb",
> -			.flag = anon_huge_flags | MAP_HUGE_512MB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_512MB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_1GB] = {
>   			.name = "anonymous_hugetlb_1gb",
> -			.flag = anon_huge_flags | MAP_HUGE_1GB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_1GB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_2GB] = {
>   			.name = "anonymous_hugetlb_2gb",
> -			.flag = anon_huge_flags | MAP_HUGE_2GB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_2GB,
>   		},
>   		[VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB] = {
>   			.name = "anonymous_hugetlb_16gb",
> -			.flag = anon_huge_flags | MAP_HUGE_16GB,
> +			.flag = ANON_HUGE_FLAGS | MAP_HUGE_16GB,
>   		},
>   		[VM_MEM_SRC_SHMEM] = {
>   			.name = "shmem",

Queued, thanks.

Paolo