[PATCH v2 04/11] powerpc/mce_power: Applies counting method to monitor lockless pgtbl walks

[Leonardo Bras]

Applies the counting-based method for monitoring lockless pgtable walks on
addr_to_pfn().

Signed-off-by: Leonardo Bras <leona...@linux.ibm.com>
---
 arch/powerpc/kernel/mce_power.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c
index a814d2dfb5b0..0f2f87da4cd1 100644
--- a/arch/powerpc/kernel/mce_power.c
+++ b/arch/powerpc/kernel/mce_power.c
@@ -27,6 +27,7 @@ unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long 
addr)
 {
        pte_t *ptep;
        unsigned long flags;
+       unsigned long pfn;
        struct mm_struct *mm;
 
        if (user_mode(regs))
@@ -34,15 +35,21 @@ unsigned long addr_to_pfn(struct pt_regs *regs, unsigned 
long addr)
        else
                mm = &init_mm;
 
+       start_lockless_pgtbl_walk(mm);
        local_irq_save(flags);
        if (mm == current->mm)
                ptep = find_current_mm_pte(mm->pgd, addr, NULL, NULL);
        else
                ptep = find_init_mm_pte(addr, NULL);
-       local_irq_restore(flags);
+
        if (!ptep || pte_special(*ptep))
-               return ULONG_MAX;
-       return pte_pfn(*ptep);
+               pfn = ULONG_MAX;
+       else
+               pfn = pte_pfn(*ptep);
+
+       local_irq_restore(flags);
+       end_lockless_pgtbl_walk(mm);
+       return pfn;
 }
 
 /* flush SLBs and reload */
-- 
2.20.1