From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Wed, 20 Oct 2021 19:21:17 +0000 (-0400)
Subject: maple-tree: Handle external locking in mt_set_in_rcu()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=c53374f930272a4c8be448021c5049c57b97da38;p=users%2Fwilly%2Flinux.git

maple-tree: Handle external locking in mt_set_in_rcu()

If the tree is marked as externally locked, we must not take the
ma_lock.  Instead, assert that the external lock is held.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 91765810e5928..f94a8796d758f 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -468,9 +468,14 @@ static inline void mt_clear_in_rcu(struct maple_tree *mt)
 	if (!mt_in_rcu(mt))
 		return;
 
-	mtree_lock(mt);
-	mt->ma_flags &= ~MT_FLAGS_USE_RCU;
-	mtree_unlock(mt);
+	if (mt_external_lock(mt)) {
+		BUG_ON(!lock_is_held(mt->ma_external_lock));
+		mt->ma_flags &= ~MT_FLAGS_USE_RCU;
+	} else {
+		mtree_lock(mt);
+		mt->ma_flags &= ~MT_FLAGS_USE_RCU;
+		mtree_unlock(mt);
+	}
 }
 
 /**
@@ -481,9 +486,14 @@ static inline void mt_set_in_rcu(struct maple_tree *mt)
 	if (mt_in_rcu(mt))
 		return;
 
-	mtree_lock(mt);
-	mt->ma_flags |= MT_FLAGS_USE_RCU;
-	mtree_unlock(mt);
+	if (mt_external_lock(mt)) {
+		BUG_ON(!lock_is_held(mt->ma_external_lock));
+		mt->ma_flags |= MT_FLAGS_USE_RCU;
+	} else {
+		mtree_lock(mt);
+		mt->ma_flags |= MT_FLAGS_USE_RCU;
+		mtree_unlock(mt);
+	}
 }
 
 void *mt_find(struct maple_tree *mt, unsigned long *index, unsigned long max);