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    Subject[patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young}
    Add ptep_test_and_clear_{dirty,young} to i386.  They advertise that they
    have it and there is at least one place where it needs to be called
    without the page table lock: to clear the accessed bit on write to
    /proc/pid/clear_refs.

    ptep_clear_flush_{dirty,young} are updated to use the new functions. The
    overall net effect to current users of ptep_clear_flush_{dirty,young} is
    that we introduce an additional branch.

    Cc: Hugh Dickins <hugh@veritas.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Signed-off-by: David Rientjes <rientjes@google.com>
    ---
    include/asm-i386/pgtable.h | 25 +++++++++++++++++--------
    1 files changed, 17 insertions(+), 8 deletions(-)

    diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
    --- a/include/asm-i386/pgtable.h
    +++ b/include/asm-i386/pgtable.h
    @@ -283,12 +283,23 @@ do { \
    } \
    } while (0)

    -/*
    - * We don't actually have these, but we want to advertise them so that
    - * we can encompass the flush here.
    - */
    #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
    +static inline int ptep_test_and_clear_dirty(struct vm_area_struct *vma,
    + unsigned long addr, pte_t *ptep)
    +{
    + if (!pte_dirty(*ptep))
    + return 0;
    + return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low);
    +}
    +
    #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
    +static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
    + unsigned long addr, pte_t *ptep)
    +{
    + if (!pte_young(*ptep))
    + return 0;
    + return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte_low);
    +}

    /*
    * Rules for using ptep_establish: the pte MUST be a user pte, and
    @@ -305,9 +316,8 @@ do { \
    #define ptep_clear_flush_dirty(vma, address, ptep) \
    ({ \
    int __dirty; \
    - __dirty = pte_dirty(*(ptep)); \
    + __dirty = ptep_test_and_clear_dirty((vma), (address), (ptep)); \
    if (__dirty) { \
    - clear_bit(_PAGE_BIT_DIRTY, &(ptep)->pte_low); \
    pte_update_defer((vma)->vm_mm, (address), (ptep)); \
    flush_tlb_page(vma, address); \
    } \
    @@ -318,9 +328,8 @@ do { \
    #define ptep_clear_flush_young(vma, address, ptep) \
    ({ \
    int __young; \
    - __young = pte_young(*(ptep)); \
    + __young = ptep_test_and_clear_young((vma), (address), (ptep)); \
    if (__young) { \
    - clear_bit(_PAGE_BIT_ACCESSED, &(ptep)->pte_low); \
    pte_update_defer((vma)->vm_mm, (address), (ptep)); \
    flush_tlb_page(vma, address); \
    } \
    -
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      Last update: 2007-03-26 02:39    [W:0.022 / U:31.296 seconds]
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