[PATCH v3 2/9] maple_tree: Introduce {mtree,mas}_lock_nested()

[Peng Zhang]

In some cases, nested locks may be needed, so {mtree,mas}_lock_nested is
introduced. For example, when duplicating maple tree, we need to hold
the locks of two trees, in which case nested locks are needed.

At the same time, add the definition of spin_lock_nested() in tools for
testing.

Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
---
 include/linux/maple_tree.h     | 4 ++++
 tools/include/linux/spinlock.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index e41c70ac7744..666a3764ed89 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -256,6 +256,8 @@ struct maple_tree {
 	struct maple_tree name = MTREE_INIT(name, 0)
 
 #define mtree_lock(mt)		spin_lock((&(mt)->ma_lock))
+#define mtree_lock_nested(mas, subclass) \
+		spin_lock_nested((&(mt)->ma_lock), subclass)
 #define mtree_unlock(mt)	spin_unlock((&(mt)->ma_lock))
 
 /*
@@ -406,6 +408,8 @@ struct ma_wr_state {
 };
 
 #define mas_lock(mas)           spin_lock(&((mas)->tree->ma_lock))
+#define mas_lock_nested(mas, subclass) \
+		spin_lock_nested(&((mas)->tree->ma_lock), subclass)
 #define mas_unlock(mas)         spin_unlock(&((mas)->tree->ma_lock))
 
 
diff --git a/tools/include/linux/spinlock.h b/tools/include/linux/spinlock.h
index 622266b197d0..a6cdf25b6b9d 100644
--- a/tools/include/linux/spinlock.h
+++ b/tools/include/linux/spinlock.h
@@ -11,6 +11,7 @@
 #define spin_lock_init(x)	pthread_mutex_init(x, NULL)
 
 #define spin_lock(x)			pthread_mutex_lock(x)
+#define spin_lock_nested(x, subclass)	pthread_mutex_lock(x)
 #define spin_unlock(x)			pthread_mutex_unlock(x)
 #define spin_lock_bh(x)			pthread_mutex_lock(x)
 #define spin_unlock_bh(x)		pthread_mutex_unlock(x)
-- 
2.20.1