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    Subject[PATCH v2 04/11] powerpc/mce_power: Applies counting method to monitor lockless pgtbl walks
    Date
    Applies the counting-based method for monitoring lockless pgtable walks on
    addr_to_pfn().

    Signed-off-by: Leonardo Bras <leonardo@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
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