1 files changed, 137 insertions, 0 deletions
diff --git a/include/linux/generic-radix-tree.h b/include/linux/generic-radix-tree.h
new file mode 100644
index 00000000..1a951e97
--- /dev/null
+++ b/include/linux/generic-radix-tree.h
@@ -0,0 +1,137 @@
+#ifndef _LINUX_GENERIC_RADIX_TREE_H
+#define _LINUX_GENERIC_RADIX_TREE_H
+
+/*
+ * Generic radix trees/sparse arrays:
+ *
+ * A generic radix tree has all nodes of size PAGE_SIZE - both leaves and
+ * interior nodes.
+ */
+
+#include <linux/page.h>
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+
+struct genradix_node;
+
+struct __genradix {
+	struct genradix_node		*root;
+	size_t				depth;
+};
+
+/*
+ * NOTE: currently, sizeof(_type) must be a power of two and not larger than
+ * PAGE_SIZE:
+ */
+
+#define __GENRADIX_INITIALIZER					\
+	{							\
+		.tree = {					\
+			.root = NULL,				\
+			.depth = 0,				\
+		}						\
+	}
+
+/*
+ * We use a 0 size array to stash the type we're storing without taking any
+ * space at runtime - then the various accessor macros can use typeof() to get
+ * to it for casts/sizeof - we also force the alignment so that storing a type
+ * with a ridiculous alignment doesn't blow up the alignment or size of the
+ * genradix.
+ */
+
+#define DECLARE_GENRADIX_TYPE(_name, _type)			\
+struct _name {							\
+	struct __genradix	tree;				\
+	_type			type[0] __aligned(1);		\
+}
+
+#define DECLARE_GENRADIX(_name, _type)				\
+struct {							\
+	struct __genradix	tree;				\
+	_type			type[0] __aligned(1);		\
+} _name
+
+#define DEFINE_GENRADIX(_name, _type)				\
+	DECLARE_GENRADIX(_name, _type) = __GENRADIX_INITIALIZER
+
+#define genradix_init(_radix)					\
+do {								\
+	*(_radix) = (typeof(*_radix)) __GENRADIX_INITIALIZER;	\
+} while (0)
+
+void __genradix_free(struct __genradix *);
+
+#define genradix_free(_radix)	__genradix_free(&(_radix)->tree)
+
+static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
+{
+	BUILD_BUG_ON(obj_size > PAGE_SIZE);
+
+	if (!is_power_of_2(obj_size)) {
+		size_t objs_per_page = PAGE_SIZE / obj_size;
+
+		return (idx / objs_per_page) * PAGE_SIZE +
+			(idx % objs_per_page) * obj_size;
+	} else {
+		return idx * obj_size;
+	}
+}
+
+#define __genradix_cast(_radix)		(typeof((_radix)->type[0]) *)
+#define __genradix_obj_size(_radix)	sizeof((_radix)->type[0])
+#define __genradix_idx_to_offset(_radix, _idx)			\
+	__idx_to_offset(_idx, __genradix_obj_size(_radix))
+
+void *__genradix_ptr(struct __genradix *, size_t);
+
+/* Returns a pointer to element at @_idx */
+#define genradix_ptr(_radix, _idx)				\
+	(__genradix_cast(_radix)				\
+	 __genradix_ptr(&(_radix)->tree,			\
+			__genradix_idx_to_offset(_radix, _idx)))
+
+void *__genradix_ptr_alloc(struct __genradix *, size_t, gfp_t);
+
+/* Returns a pointer to element at @_idx, allocating it if necessary */
+#define genradix_ptr_alloc(_radix, _idx, _gfp)			\
+	(__genradix_cast(_radix)				\
+	 __genradix_ptr_alloc(&(_radix)->tree,			\
+			__genradix_idx_to_offset(_radix, _idx),	\
+			_gfp))
+
+struct genradix_iter {
+	size_t			offset;
+	size_t			pos;
+};
+
+static inline void genradix_iter_init(struct genradix_iter *iter)
+{
+	iter->offset	= 0;
+	iter->pos	= 0;
+}
+
+void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t);
+
+#define genradix_iter_peek(_iter, _radix)			\
+	(__genradix_cast(_radix)				\
+	 __genradix_iter_peek(_iter, &(_radix)->tree,		\
+			      PAGE_SIZE / __genradix_obj_size(_radix)))
+
+static inline void __genradix_iter_advance(struct genradix_iter *iter,
+					   size_t obj_size)
+{
+	iter->offset += obj_size;
+
+	if (!is_power_of_2(obj_size) &&
+	    (iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE)
+		iter->offset = round_up(iter->offset, PAGE_SIZE);
+
+	iter->pos++;
+}
+
+#define genradix_iter_advance(_iter, _radix)			\
+	__genradix_iter_advance(_iter, __genradix_obj_size(_radix))
+
+#endif /* _LINUX_GENERIC_RADIX_TREE_H */