linux-kernel - [tip:x86/urgent] x86/vm86: Fix unused variable warning if THP is disabled

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Message-ID: <tip-3ba5b5ea7dc3a10ef50819b43a9f8de2705f4eec@git.kernel.org>
Date:   Mon, 13 Feb 2017 10:07:03 -0800
From:   "tip-bot for Kirill A. Shutemov" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, jeremy.lefaure@....epita.fr, carlos@...hat.com,
        kirill.shutemov@...ux.intel.com, hpa@...or.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, bp@...e.de
Subject: [tip:x86/urgent] x86/vm86: Fix unused variable warning if THP is
 disabled

Commit-ID:  3ba5b5ea7dc3a10ef50819b43a9f8de2705f4eec
Gitweb:     http://git.kernel.org/tip/3ba5b5ea7dc3a10ef50819b43a9f8de2705f4eec
Author:     Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
AuthorDate: Mon, 13 Feb 2017 15:52:28 +0300
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 13 Feb 2017 19:04:38 +0100

x86/vm86: Fix unused variable warning if THP is disabled

GCC complains about unused variable 'vma' in mark_screen_rdonly() if THP is
disabled:

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);

That's silly. pmd_trans_huge() resolves to 0 when THP is disabled, so the
whole block should be eliminated.

Moving the variable declaration outside the if() block shuts GCC up.

Reported-by: Jérémy Lefaure <jeremy.lefaure@....epita.fr>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Tested-by: Borislav Petkov <bp@...e.de>
Cc: Carlos O'Donell <carlos@...hat.com>
Link: http://lkml.kernel.org/r/20170213125228.63645-1-kirill.shutemov@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/kernel/vm86_32.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index ec5d754..0442d98 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -160,11 +160,12 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
 
 static void mark_screen_rdonly(struct mm_struct *mm)
 {
+	struct vm_area_struct *vma;
+	spinlock_t *ptl;
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
-	spinlock_t *ptl;
 	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))