[PATCH drm-next v4 02/14] maple_tree: split up MA_STATE() macro

[Danilo Krummrich <dakr@redhat.com>]

Split up the MA_STATE() macro such that components using the maple tree
can easily inherit from struct ma_state and build custom tree walk
macros to hide their internals from users.

Example:

struct sample_iterator {
	struct ma_state mas;
	struct sample_mgr *mgr;
};

\#define SAMPLE_ITERATOR(name, __mgr, start)			\
	struct sample_iterator name = {				\
		.mas = MA_STATE_INIT(&(__mgr)->mt, start, 0),	\
		.mgr = __mgr,					\
	}

\#define sample_iter_for_each_range(it__, entry__, end__) \
	mas_for_each(&(it__).mas, entry__, end__)

--

struct sample *sample;
SAMPLE_ITERATOR(si, min);

sample_iter_for_each_range(&si, sample, max) {
	frob(mgr, sample);
}

Signed-off-by: Danilo Krummrich <dakr@redhat.com>
---
 include/linux/maple_tree.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 1fadb5f5978b..87d55334f1c2 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -423,8 +423,8 @@ struct ma_wr_state {
 #define MA_ERROR(err) \
 		((struct maple_enode *)(((unsigned long)err << 2) | 2UL))
 
-#define MA_STATE(name, mt, first, end)					\
-	struct ma_state name = {					\
+#define MA_STATE_INIT(mt, first, end)					\
+	{								\
 		.tree = mt,						\
 		.index = first,						\
 		.last = end,						\
@@ -435,6 +435,9 @@ struct ma_wr_state {
 		.mas_flags = 0,						\
 	}
 
+#define MA_STATE(name, mt, first, end)					\
+	struct ma_state name = MA_STATE_INIT(mt, first, end)
+
 #define MA_WR_STATE(name, ma_state, wr_entry)				\
 	struct ma_wr_state name = {					\
 		.mas = ma_state,					\
-- 
2.40.1