linux-kernel - [PATCH] x86/vm86: fix unused variable warning if THP is disabled.

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Date:   Mon, 13 Feb 2017 15:52:28 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Jérémy Lefaure 
        <jeremy.lefaure@....epita.fr>, x86@...nel.org,
        Borislav Petkov <bp@...e.de>
Cc:     linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH] x86/vm86: fix unused variable warning if THP is disabled.

GCC complaines on unused variable 'vma' in mark_screen_rdonly() if THP
is disalbed:

arch/x86/kernel/vm86_32.c: In function ‘mark_screen_rdonly’:
arch/x86/kernel/vm86_32.c:180:26: warning: unused variable ‘vma’
[-Wunused-variable]
   struct vm_area_struct *vma = find_vma(mm, 0xA0000);
                             ^~~
It shoudln't really. The whole block has to be eliminated as
pmd_trans_huge() is 0 if THP is disabled.

Anyway, this trick seems make GCC happy.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reported-by: Jérémy Lefaure <jeremy.lefaure@....epita.fr>
---
 arch/x86/kernel/vm86_32.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index ec5d7545e6dc..8cdbd32ededc 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -165,6 +165,7 @@ static void mark_screen_rdonly(struct mm_struct *mm)
 	pmd_t *pmd;
 	pte_t *pte;
 	spinlock_t *ptl;
+	struct vm_area_struct *vma;
 	int i;
 
 	down_write(&mm->mmap_sem);
@@ -177,7 +178,7 @@ static void mark_screen_rdonly(struct mm_struct *mm)
 	pmd = pmd_offset(pud, 0xA0000);
 
 	if (pmd_trans_huge(*pmd)) {
-		struct vm_area_struct *vma = find_vma(mm, 0xA0000);
+		vma = find_vma(mm, 0xA0000);
 		split_huge_pmd(vma, pmd, 0xA0000);
 	}
 	if (pmd_none_or_clear_bad(pmd))
-- 
2.11.0