in_atomic(): document why it is unsuitable for general use

[sfrench/cifs-2.6.git] / include / linux / highmem.h

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 1fcb0033179ec4e68442a5cc389c8f93a6bcd528..7dcbc82f3b7bf4a19969d0cf19824cf373a2a91b 100644 (file)
--- 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
@@ -124,28 +122,40 @@ static inline void clear_highpage(struct page *page)
        kunmap_atomic(kaddr, KM_USER0);
 }
 
-/*
- * Same but also flushes aliased cache contents to RAM.
- *
- * This must be a macro because KM_USER0 and friends aren't defined if
- * !CONFIG_HIGHMEM
- */
-#define zero_user_page(page, offset, size, km_type)            \
-       do {                                                    \
-               void *kaddr;                                    \
-                                                               \
-               BUG_ON((offset) + (size) > PAGE_SIZE);          \
-                                                               \
-               kaddr = kmap_atomic(page, km_type);             \
-               memset((char *)kaddr + (offset), 0, (size));    \
-               flush_dcache_page(page);                        \
-               kunmap_atomic(kaddr, (km_type));                \
-       } while (0)
+static inline void zero_user_segments(struct page *page,
+       unsigned start1, unsigned end1,
+       unsigned start2, unsigned end2)
+{
+       void *kaddr = kmap_atomic(page, KM_USER0);
+
+       BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
+
+       if (end1 > start1)
+               memset(kaddr + start1, 0, end1 - start1);
+
+       if (end2 > start2)
+               memset(kaddr + start2, 0, end2 - start2);
+
+       kunmap_atomic(kaddr, KM_USER0);
+       flush_dcache_page(page);
+}
+
+static inline void zero_user_segment(struct page *page,
+       unsigned start, unsigned end)
+{
+       zero_user_segments(page, start, end, 0, 0);
+}
+
+static inline void zero_user(struct page *page,
+       unsigned start, unsigned size)
+{
+       zero_user_segments(page, start, start + size, 0, 0);
+}
 
 static inline void __deprecated memclear_highpage_flush(struct page *page,
                        unsigned int offset, unsigned int size)
 {
-       zero_user_page(page, offset, size, KM_USER0);
+       zero_user(page, offset, size);
 }
 
 #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
@@ -160,8 +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