linux-kernel - [PATCH v2 2/4] maple_tree: Relax lockdep checks for on-stack trees

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Message-Id: <20230714195551.894800-3-Liam.Howlett@oracle.com>
Date:   Fri, 14 Jul 2023 15:55:49 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH v2 2/4] maple_tree: Relax lockdep checks for on-stack trees

To support early release of the maple tree locks, do not lockdep check
the lock if it is set to NULL.  This is intended for the special case
on-stack use of tracking entries and not for general use.

Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 include/linux/maple_tree.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 7769270b85e8..6618c1512886 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -182,7 +182,9 @@ enum maple_type {
 
 #ifdef CONFIG_LOCKDEP
 typedef struct lockdep_map *lockdep_map_p;
-#define mt_lock_is_held(mt)	lock_is_held(mt->ma_external_lock)
+#define mt_lock_is_held(mt)                                             \
+	(!(mt)->ma_external_lock || lock_is_held((mt)->ma_external_lock))
+
 #define mt_set_external_lock(mt, lock)					\
 	(mt)->ma_external_lock = &(lock)->dep_map
 #else
-- 
2.39.2