linux-kernel - [PATCH V2 4/4] arm64/mm: Drop local variable vm_fault_t from __do_page

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Date:   Mon,  3 Jun 2019 12:11:25 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Christoph Hellwig <hch@...radead.org>
Subject: [PATCH V2 4/4] arm64/mm: Drop local variable vm_fault_t from __do_page_fault()

__do_page_fault() is over complicated with multiple goto statements. This
cleans up the code flow and while there drops local variable vm_fault_t.

Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: James Morse <james.morse@....com>
Cc: Andrey Konovalov <andreyknvl@...gle.com>
Cc: Christoph Hellwig <hch@...radead.org>
---
 arch/arm64/mm/fault.c | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 4bb65f3..41fa905 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -397,37 +397,29 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
 static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
 			   unsigned int mm_flags, unsigned long vm_flags)
 {
-	struct vm_area_struct *vma;
-	vm_fault_t fault;
+	struct vm_area_struct *vma = find_vma(mm, addr);
 
-	vma = find_vma(mm, addr);
-	fault = VM_FAULT_BADMAP;
 	if (unlikely(!vma))
-		goto out;
-	if (unlikely(vma->vm_start > addr))
-		goto check_stack;
+		return VM_FAULT_BADMAP;
 
 	/*
 	 * Ok, we have a good vm_area for this memory access, so we can handle
 	 * it.
 	 */
-good_area:
+	if (unlikely(vma->vm_start > addr)) {
+		if (!(vma->vm_flags & VM_GROWSDOWN))
+			return VM_FAULT_BADMAP;
+		if (expand_stack(vma, addr))
+			return VM_FAULT_BADMAP;
+	}
+
 	/*
 	 * Check that the permissions on the VMA allow for the fault which
 	 * occurred.
 	 */
-	if (!(vma->vm_flags & vm_flags)) {
-		fault = VM_FAULT_BADACCESS;
-		goto out;
-	}
-
+	if (!(vma->vm_flags & vm_flags))
+		return VM_FAULT_BADACCESS;
 	return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
-
-check_stack:
-	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
-		goto good_area;
-out:
-	return fault;
 }
 
 static bool is_el0_instruction_abort(unsigned int esr)
-- 
2.7.4