Merge branch 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, pat: Update the page flags for memtype atomically instead of using memtype_lock
  x86, pat: In rbt_memtype_check_insert(), update new->type only if valid
  x86, pat: Migrate to rbtree only backend for pat memtype management
  x86, pat: Preparatory changes in pat.c for bigger rbtree change
  rbtree: Add support for augmented rbtrees

1 files changed, 25 insertions, 19 deletions

diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 634c40a739a6..c70068d05f70 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -44,9 +44,6 @@ static inline void copy_from_user_page(struct vm_area_struct *vma,
         memcpy(dst, src, len);
 }
 
-#define PG_WC                           PG_arch_1
-PAGEFLAG(WC, WC)
-
 #ifdef CONFIG_X86_PAT
 /*
  * X86 PAT uses page flags WC and Uncached together to keep track of
@@ -55,16 +52,24 @@ PAGEFLAG(WC, WC)
  * _PAGE_CACHE_UC_MINUS and fourth state where page's memory type has not
  * been changed from its default (value of -1 used to denote this).
  * Note we do not support _PAGE_CACHE_UC here.
- *
- * Caller must hold memtype_lock for atomicity.
  */
+
+#define _PGMT_DEFAULT           0
+#define _PGMT_WC                (1UL << PG_arch_1)
+#define _PGMT_UC_MINUS          (1UL << PG_uncached)
+#define _PGMT_WB                (1UL << PG_uncached | 1UL << PG_arch_1)
+#define _PGMT_MASK              (1UL << PG_uncached | 1UL << PG_arch_1)
+#define _PGMT_CLEAR_MASK        (~_PGMT_MASK)
+
 static inline unsigned long get_page_memtype(struct page *pg)
 {
-        if (!PageUncached(pg) && !PageWC(pg))
+        unsigned long pg_flags = pg->flags & _PGMT_MASK;
+
+        if (pg_flags == _PGMT_DEFAULT)
                 return -1;
-        else if (!PageUncached(pg) && PageWC(pg))
+        else if (pg_flags == _PGMT_WC)
                 return _PAGE_CACHE_WC;
-        else if (PageUncached(pg) && !PageWC(pg))
+        else if (pg_flags == _PGMT_UC_MINUS)
                 return _PAGE_CACHE_UC_MINUS;
         else
                 return _PAGE_CACHE_WB;
@@ -72,25 +77,26 @@ static inline unsigned long get_page_memtype(struct page *pg)
 
 static inline void set_page_memtype(struct page *pg, unsigned long memtype)
 {
+        unsigned long memtype_flags = _PGMT_DEFAULT;
+        unsigned long old_flags;
+        unsigned long new_flags;
+
         switch (memtype) {
         case _PAGE_CACHE_WC:
-                ClearPageUncached(pg);
-                SetPageWC(pg);
+                memtype_flags = _PGMT_WC;
                 break;
         case _PAGE_CACHE_UC_MINUS:
-                SetPageUncached(pg);
-                ClearPageWC(pg);
+                memtype_flags = _PGMT_UC_MINUS;
                 break;
         case _PAGE_CACHE_WB:
-                SetPageUncached(pg);
-                SetPageWC(pg);
-                break;
-        default:
-        case -1:
-                ClearPageUncached(pg);
-                ClearPageWC(pg);
+                memtype_flags = _PGMT_WB;
                 break;
         }
+
+        do {
+                old_flags = pg->flags;
+                new_flags = (old_flags & _PGMT_CLEAR_MASK) | memtype_flags;
+        } while (cmpxchg(&pg->flags, old_flags, new_flags) != old_flags);
 }
 #else
 static inline unsigned long get_page_memtype(struct page *pg) { return -1; }