mm: move tlb_flush_pending inline helpers to mm_inline.h

[uclinux-h8/linux.git] / include / linux / mm_inline.h

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 47d96d2..b725839 100644 (file)
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -2,6 +2,7 @@
 #ifndef LINUX_MM_INLINE_H
 #define LINUX_MM_INLINE_H
 
+#include <linux/atomic.h>
 #include <linux/huge_mm.h>
 #include <linux/swap.h>
 #include <linux/string.h>
@@ -185,4 +186,89 @@ static inline bool is_same_vma_anon_name(struct vm_area_struct *vma,
 }
 #endif  /* CONFIG_ANON_VMA_NAME */
 
+static inline void init_tlb_flush_pending(struct mm_struct *mm)
+{
+       atomic_set(&mm->tlb_flush_pending, 0);
+}
+
+static inline void inc_tlb_flush_pending(struct mm_struct *mm)
+{
+       atomic_inc(&mm->tlb_flush_pending);
+       /*
+        * 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:
+        *
+        *      atomic_inc(&mm->tlb_flush_pending);
+        *      spin_lock(&ptl);
+        *      ...
+        *      set_pte_at();
+        *      spin_unlock(&ptl);
+        *
+        *                              spin_lock(&ptl)
+        *                              mm_tlb_flush_pending();
+        *                              ....
+        *                              spin_unlock(&ptl);
+        *
+        *      flush_tlb_range();
+        *      atomic_dec(&mm->tlb_flush_pending);
+        *
+        * Where the increment if constrained by the PTL unlock, it thus
+        * ensures that the increment is visible if the PTE modification is
+        * visible. After all, if there is no PTE modification, nobody cares
+        * about TLB flushes either.
+        *
+        * This very much relies on users (mm_tlb_flush_pending() and
+        * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
+        * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
+        * locks (PPC) the unlock of one doesn't order against the lock of
+        * another PTL.
+        *
+        * The decrement is ordered by the flush_tlb_range(), such that
+        * mm_tlb_flush_pending() will not return false unless all flushes have
+        * completed.
+        */
+}
+
+static inline void dec_tlb_flush_pending(struct mm_struct *mm)
+{
+       /*
+        * See inc_tlb_flush_pending().
+        *
+        * This cannot be smp_mb__before_atomic() because smp_mb() simply does
+        * not order against TLB invalidate completion, which is what we need.
+        *
+        * Therefore we must rely on tlb_flush_*() to guarantee order.
+        */
+       atomic_dec(&mm->tlb_flush_pending);
+}
+
+static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
+{
+       /*
+        * Must be called after having acquired the PTL; orders against that
+        * PTLs release and therefore ensures that if we observe the modified
+        * PTE we must also observe the increment from inc_tlb_flush_pending().
+        *
+        * That is, it only guarantees to return true if there is a flush
+        * pending for _this_ PTL.
+        */
+       return atomic_read(&mm->tlb_flush_pending);
+}
+
+static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
+{
+       /*
+        * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
+        * for which there is a TLB flush pending in order to guarantee
+        * we've seen both that PTE modification and the increment.
+        *
+        * (no requirement on actually still holding the PTL, that is irrelevant)
+        */
+       return atomic_read(&mm->tlb_flush_pending) > 1;
+}
+
+
 #endif