summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--include/linux/mm_types.h14
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