lib: Export interval_tree

lib/interval_tree.c provides a simple interface for an interval-tree
(an augmented red-black tree) but is only built when testing the generic
macros for building interval-trees. For drivers with modest needs,
export the simple interval-tree library as is.

v2: Lots of help from Michel Lespinasse to only compile the code
as required:
- make INTERVAL_TREE a config option
- make INTERVAL_TREE_TEST select the library functions
and sanitize the filenames & Makefile
- prepare interval_tree for being built as a module if required

Signed-off-by: Chris Wilson <[e-mail]>
Cc: Michel Lespinasse <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Andrea Arcangeli <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Reviewed-by: Michel Lespinasse <[e-mail]>
[Acked for inclusion via drm/i915 by Andrew Morton.]
[danvet: switch to _GPL as per the mailing list discussion.]
Signed-off-by: Daniel Vetter <[e-mail]>

lib/Kconfig

···
 config BTREE
 	boolean
 
+config INTERVAL_TREE
+	boolean
+	help
+	  Simple, embeddable, interval-tree. Can find the start of an
+	  overlapping range in log(n) time and then iterate over all
+	  overlapping nodes. The algorithm is implemented as an
+	  augmented rbtree.
+
+	  See:
+
+		Documentation/rbtree.txt
+
+	  for more information.
+
 config ASSOCIATIVE_ARRAY
 	bool
 	help

lib/Kconfig.debug

···
 config INTERVAL_TREE_TEST
 	tristate "Interval tree test"
 	depends on m && DEBUG_KERNEL
+	select INTERVAL_TREE
 	help
 	  A benchmark measuring the performance of the interval tree library
 

lib/Makefile

···
 obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
 
 obj-$(CONFIG_BTREE) += btree.o
+obj-$(CONFIG_INTERVAL_TREE) += interval_tree.o
 obj-$(CONFIG_ASSOCIATIVE_ARRAY) += assoc_array.o
 obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
 obj-$(CONFIG_DEBUG_LIST) += list_debug.o
···
 
 obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
 obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
-
-interval_tree_test-objs := interval_tree_test_main.o interval_tree.o
 
 obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
 

lib/interval_tree.c

···
 #include <linux/init.h>
 #include <linux/interval_tree.h>
 #include <linux/interval_tree_generic.h>
+#include <linux/module.h>
 
 #define START(node) ((node)->start)
 #define LAST(node)  ((node)->last)
···
 INTERVAL_TREE_DEFINE(struct interval_tree_node, rb,
 		     unsigned long, __subtree_last,
 		     START, LAST,, interval_tree)
+
+EXPORT_SYMBOL_GPL(interval_tree_insert);
+EXPORT_SYMBOL_GPL(interval_tree_remove);
+EXPORT_SYMBOL_GPL(interval_tree_iter_first);
+EXPORT_SYMBOL_GPL(interval_tree_iter_next);