[PATCH -fixes] riscv: Fix build error if !CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION

[Alexandre Ghiti]

The new riscv specific arch_hugetlb_migration_supported() must be
guarded with a #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION to avoid
the following build error:

In file included from include/linux/hugetlb.h:851,
                    from kernel/fork.c:52:
>> arch/riscv/include/asm/hugetlb.h:15:42: error: static declaration of 'arch_hugetlb_migration_supported' follows non-static declaration
      15 | #define arch_hugetlb_migration_supported arch_hugetlb_migration_supported
         |                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h:916:20: note: in expansion of macro 'arch_hugetlb_migration_supported'
     916 | static inline bool arch_hugetlb_migration_supported(struct hstate *h)
         |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/riscv/include/asm/hugetlb.h:14:6: note: previous declaration of 'arch_hugetlb_migration_supported' with type 'bool(struct hstate *)' {aka '_Bool(struct hstate *)'}
      14 | bool arch_hugetlb_migration_supported(struct hstate *h);
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202402110258.CV51JlEI-lkp@xxxxxxxxx/
Fixes: ce68c035457b ("riscv: Fix arch_hugetlb_migration_supported() for NAPOT")
Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
---
 arch/riscv/include/asm/hugetlb.h | 2 ++
 arch/riscv/mm/hugetlbpage.c      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
index 20f9c3ba2341..22deb7a2a6ec 100644
--- a/arch/riscv/include/asm/hugetlb.h
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -11,8 +11,10 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 }
 #define arch_clear_hugepage_flags arch_clear_hugepage_flags
 
+#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
 bool arch_hugetlb_migration_supported(struct hstate *h);
 #define arch_hugetlb_migration_supported arch_hugetlb_migration_supported
+#endif
 
 #ifdef CONFIG_RISCV_ISA_SVNAPOT
 #define __HAVE_ARCH_HUGE_PTE_CLEAR
diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
index 29c7606414d2..5ef2a6891158 100644
--- a/arch/riscv/mm/hugetlbpage.c
+++ b/arch/riscv/mm/hugetlbpage.c
@@ -426,10 +426,12 @@ bool __init arch_hugetlb_valid_size(unsigned long size)
 	return __hugetlb_valid_size(size);
 }
 
+#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
 bool arch_hugetlb_migration_supported(struct hstate *h)
 {
 	return __hugetlb_valid_size(huge_page_size(h));
 }
+#endif
 
 #ifdef CONFIG_CONTIG_ALLOC
 static __init int gigantic_pages_init(void)
-- 
2.39.2