x86, pat: Update the page flags for memtype atomically instead of using memtype_lock
[linux-2.6.git] / arch / x86 / include / asm / cacheflush.h
index 634c40a..c70068d 100644 (file)
@@ -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; }