[PATCH v2 01/29] radix-tree: Introduce radix_tree_empty

[Matthew Wilcox]

The irqdomain code was checking for 0 or 1 entries, not 0 entries like
the comment said they were.  Introduce a new helper that will actually
check for an empty tree.

Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
 include/linux/radix-tree.h | 5 +++++
 kernel/irq/irqdomain.c     | 7 +------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 51a97ac..83f708e 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -136,6 +136,11 @@ do {									\
 	(root)->rnode = NULL;						\
 } while (0)
 
+static inline bool radix_tree_empty(struct radix_tree_root *root)
+{
+	return root->rnode == NULL;
+}
+
 /**
  * Radix-tree synchronization
  *
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 3a519a0..ba3f60d 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -139,12 +139,7 @@ void irq_domain_remove(struct irq_domain *domain)
 {
 	mutex_lock(&irq_domain_mutex);
 
-	/*
-	 * radix_tree_delete() takes care of destroying the root
-	 * node when all entries are removed. Shout if there are
-	 * any mappings left.
-	 */
-	WARN_ON(domain->revmap_tree.height);
+	WARN_ON(!radix_tree_empty(&domain->revmap_tree));
 
 	list_del(&domain->link);
 
-- 
2.8.0.rc3