diff options
Diffstat (limited to 'include/linux/mm_types.h')
| -rw-r--r-- | include/linux/mm_types.h | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 7f384bb62d8e..36ea3cf7d85e 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -531,23 +531,44 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm) */ static inline bool mm_tlb_flush_pending(struct mm_struct *mm) { - barrier(); + /* + * Must be called with PTL held; such that our PTL acquire will have + * observed the store from set_tlb_flush_pending(). + */ return mm->tlb_flush_pending; } static inline void set_tlb_flush_pending(struct mm_struct *mm) { mm->tlb_flush_pending = true; - /* - * Guarantee that the tlb_flush_pending store does not leak into the - * critical section updating the page tables + * The only time this value is relevant is when there are indeed pages + * to flush. And we'll only flush pages after changing them, which + * requires the PTL. + * + * So the ordering here is: + * + * mm->tlb_flush_pending = true; + * spin_lock(&ptl); + * ... + * set_pte_at(); + * spin_unlock(&ptl); + * + * spin_lock(&ptl) + * mm_tlb_flush_pending(); + * .... + * spin_unlock(&ptl); + * + * flush_tlb_range(); + * mm->tlb_flush_pending = false; + * + * So the =true store is constrained by the PTL unlock, and the =false + * store is constrained by the TLB invalidate. */ - smp_mb__before_spinlock(); } /* Clearing is done after a TLB flush, which also provides a barrier. */ static inline void clear_tlb_flush_pending(struct mm_struct *mm) { - barrier(); + /* see set_tlb_flush_pending */ mm->tlb_flush_pending = false; } #else |