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Diffstat (limited to 'drivers/staging/zsmalloc/zsmalloc-main.c')
-rw-r--r--drivers/staging/zsmalloc/zsmalloc-main.c17
1 files changed, 13 insertions, 4 deletions
diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
index 1a67537dbc56..3b950e5a918f 100644
--- a/drivers/staging/zsmalloc/zsmalloc-main.c
+++ b/drivers/staging/zsmalloc/zsmalloc-main.c
@@ -430,7 +430,12 @@ static struct page *get_next_page(struct page *page)
return next;
}
-/* Encode <page, obj_idx> as a single handle value */
+/*
+ * Encode <page, obj_idx> as a single handle value.
+ * On hardware platforms with physical memory starting at 0x0 the pfn
+ * could be 0 so we ensure that the handle will never be 0 by adjusting the
+ * encoded obj_idx value before encoding.
+ */
static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
{
unsigned long handle;
@@ -441,17 +446,21 @@ static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
}
handle = page_to_pfn(page) << OBJ_INDEX_BITS;
- handle |= (obj_idx & OBJ_INDEX_MASK);
+ handle |= ((obj_idx + 1) & OBJ_INDEX_MASK);
return (void *)handle;
}
-/* Decode <page, obj_idx> pair from the given object handle */
+/*
+ * Decode <page, obj_idx> pair from the given object handle. We adjust the
+ * decoded obj_idx back to its original value since it was adjusted in
+ * obj_location_to_handle().
+ */
static void obj_handle_to_location(unsigned long handle, struct page **page,
unsigned long *obj_idx)
{
*page = pfn_to_page(handle >> OBJ_INDEX_BITS);
- *obj_idx = handle & OBJ_INDEX_MASK;
+ *obj_idx = (handle & OBJ_INDEX_MASK) - 1;
}
static unsigned long obj_idx_to_offset(struct page *page,