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-rw-r--r--include/linux/highmem.h4
-rw-r--r--include/linux/page-flags.h42
2 files changed, 39 insertions, 7 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 61a5e5e..7dcbc82 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -68,8 +68,6 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
void *addr = kmap_atomic(page, KM_USER0);
clear_user_page(addr, vaddr, page);
kunmap_atomic(addr, KM_USER0);
- /* Make sure this page is cleared on other CPU's too before using it */
- smp_wmb();
}
#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
@@ -172,8 +170,6 @@ static inline void copy_user_highpage(struct page *to, struct page *from,
copy_user_page(vto, vfrom, vaddr, to);
kunmap_atomic(vfrom, KM_USER0);
kunmap_atomic(vto, KM_USER1);
- /* Make sure this page is cleared on other CPU's too before using it */
- smp_wmb();
}
#endif
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 209d3a4..bbad43f 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -131,16 +131,52 @@
#define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
-#define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags)
+static inline int PageUptodate(struct page *page)
+{
+ int ret = test_bit(PG_uptodate, &(page)->flags);
+
+ /*
+ * Must ensure that the data we read out of the page is loaded
+ * _after_ we've loaded page->flags to check for PageUptodate.
+ * We can skip the barrier if the page is not uptodate, because
+ * we wouldn't be reading anything from it.
+ *
+ * See SetPageUptodate() for the other side of the story.
+ */
+ if (ret)
+ smp_rmb();
+
+ return ret;
+}
+
+static inline void __SetPageUptodate(struct page *page)
+{
+ smp_wmb();
+ __set_bit(PG_uptodate, &(page)->flags);
#ifdef CONFIG_S390
+ page_clear_dirty(page);
+#endif
+}
+
static inline void SetPageUptodate(struct page *page)
{
+#ifdef CONFIG_S390
if (!test_and_set_bit(PG_uptodate, &page->flags))
page_clear_dirty(page);
-}
#else
-#define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags)
+ /*
+ * Memory barrier must be issued before setting the PG_uptodate bit,
+ * so that all previous stores issued in order to bring the page
+ * uptodate are actually visible before PageUptodate becomes true.
+ *
+ * s390 doesn't need an explicit smp_wmb here because the test and
+ * set bit already provides full barriers.
+ */
+ smp_wmb();
+ set_bit(PG_uptodate, &(page)->flags);
#endif
+}
+
#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
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