linux-kernel - [PATCH] maple_tree: remove lockdep_map

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Message-ID: <20250902-maple-lockdep-p-v1-1-3ae5a398a379@google.com>
Date: Tue, 02 Sep 2025 08:36:11 +0000
From: Alice Ryhl <aliceryhl@...gle.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc: Danilo Krummrich <dakr@...nel.org>, maple-tree@...ts.infradead.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org, 
	Alice Ryhl <aliceryhl@...gle.com>
Subject: [PATCH] maple_tree: remove lockdep_map_p typedef

Having the ma_external_lock field exist when CONFIG_LOCKDEP=n isn't used
anywhere, so just get rid of it. This also avoids generating a typedef
called lockdep_map_p that could overlap with typedefs in other header
files.

Reviewed-by: Danilo Krummrich <dakr@...nel.org>
Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
---
Originally sent as
https://lore.kernel.org/all/20250819-maple-tree-v2-1-229b48657bab@google.com/

But I'm moving it out of that series as it did not have the intended
effect on the Rust bindgen output. However, I still think it makes sense
as a pure cleanup patch.
---
 include/linux/maple_tree.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index bafe143b1f783202e27b32567fffee4149e8e266..8244679ba1758235e049acbaedee62aae5c0e226 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -194,7 +194,6 @@ enum store_type {
 #define MAPLE_RESERVED_RANGE	4096
 
 #ifdef CONFIG_LOCKDEP
-typedef struct lockdep_map *lockdep_map_p;
 #define mt_lock_is_held(mt)                                             \
 	(!(mt)->ma_external_lock || lock_is_held((mt)->ma_external_lock))
 
@@ -207,7 +206,6 @@ typedef struct lockdep_map *lockdep_map_p;
 
 #define mt_on_stack(mt)			(mt).ma_external_lock = NULL
 #else
-typedef struct { /* nothing */ } lockdep_map_p;
 #define mt_lock_is_held(mt)		1
 #define mt_write_lock_is_held(mt)	1
 #define mt_set_external_lock(mt, lock)	do { } while (0)
@@ -230,8 +228,10 @@ typedef struct { /* nothing */ } lockdep_map_p;
  */
 struct maple_tree {
 	union {
-		spinlock_t	ma_lock;
-		lockdep_map_p	ma_external_lock;
+		spinlock_t		ma_lock;
+#ifdef CONFIG_LOCKDEP
+		struct lockdep_map	*ma_external_lock;
+#endif
 	};
 	unsigned int	ma_flags;
 	void __rcu      *ma_root;

---
base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00
change-id: 20250902-maple-lockdep-p-a930e865c76b

Best regards,
-- 
Alice Ryhl <aliceryhl@...gle.com>