diff options
| -rw-r--r-- | include/linux/mm_types.h | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index f58f76ee1dfa..0e478ebd2706 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -526,12 +526,12 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm) /* * Memory barriers to keep this state in sync are graciously provided by * the page table locks, outside of which no page table modifications happen. - * The barriers below prevent the compiler from re-ordering the instructions - * around the memory barriers that are already present in the code. + * The barriers are used to ensure the order between tlb_flush_pending updates, + * which happen while the lock is not taken, and the PTE updates, which happen + * while the lock is taken, are serialized. */ static inline bool mm_tlb_flush_pending(struct mm_struct *mm) { - barrier(); return atomic_read(&mm->tlb_flush_pending) > 0; } @@ -554,7 +554,13 @@ static inline void inc_tlb_flush_pending(struct mm_struct *mm) /* Clearing is done after a TLB flush, which also provides a barrier. */ static inline void dec_tlb_flush_pending(struct mm_struct *mm) { - barrier(); + /* + * Guarantee that the tlb_flush_pending does not not leak into the + * critical section, since we must order the PTE change and changes to + * the pending TLB flush indication. We could have relied on TLB flush + * as a memory barrier, but this behavior is not clearly documented. + */ + smp_mb__before_atomic(); atomic_dec(&mm->tlb_flush_pending); } #else |