Merge remote-tracking branch 'tip/auto-latest'

[karo-tx-linux.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 81443d557a2e179a7d3768c63abc2519d9d1ed19..8aa4006b9636e11dbcb4e32e988f43c30c865396 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -297,12 +297,26 @@ static inline int put_page_testzero(struct page *page)
 /*
  * Try to grab a ref unless the page has a refcount of zero, return false if
  * that is the case.
+ * This can be called when MMU is off so it must not access
+ * any of the virtual mappings.
  */
 static inline int get_page_unless_zero(struct page *page)
 {
        return atomic_inc_not_zero(&page->_count);
 }
 
+/*
+ * Try to drop a ref unless the page has a refcount of one, return false if
+ * that is the case.
+ * This is to make sure that the refcount won't become zero after this drop.
+ * This can be called when MMU is off so it must not access
+ * any of the virtual mappings.
+ */
+static inline int put_page_unless_one(struct page *page)
+{
+       return atomic_add_unless(&page->_count, -1, 1);
+}
+
 extern int page_is_ram(unsigned long pfn);
 
 /* Support for virtually mapped pages */