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 98e2cce996a4c1867543ffa03d83c66c3c8846de..7dcbc82f3b7bf4a19969d0cf19824cf373a2a91b 100644 (file)
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -68,15 +68,30 @@ 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
+/**
+ * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
+ * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
+ * @vma: The VMA the page is to be allocated for
+ * @vaddr: The virtual address the page will be inserted into
+ *
+ * This function will allocate a page for a VMA but the caller is expected
+ * to specify via movableflags whether the page will be movable in the
+ * future or not
+ *
+ * An architecture may override this function by defining
+ * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
+ * implementation.
+ */
 static inline struct page *
-alloc_zeroed_user_highpage(struct vm_area_struct *vma, unsigned long vaddr)
+__alloc_zeroed_user_highpage(gfp_t movableflags,
+                       struct vm_area_struct *vma,
+                       unsigned long vaddr)
 {
-       struct page *page = alloc_page_vma(GFP_HIGHUSER, vma, vaddr);
+       struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
+                       vma, vaddr);
 
        if (page)
                clear_user_highpage(page, vaddr);
@@ -85,6 +100,21 @@ alloc_zeroed_user_highpage(struct vm_area_struct *vma, unsigned long vaddr)
 }
 #endif
 
+/**
+ * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
+ * @vma: The VMA the page is to be allocated for
+ * @vaddr: The virtual address the page will be inserted into
+ *
+ * This function will allocate a page for a VMA that the caller knows will
+ * be able to migrate in the future using move_pages() or reclaimed
+ */
+static inline struct page *
+alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+                                       unsigned long vaddr)
+{
+       return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
+}
+
 static inline void clear_highpage(struct page *page)
 {
        void *kaddr = kmap_atomic(page, KM_USER0);
@@ -92,28 +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
@@ -128,8 +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