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; }