From 19a462f06eb5a78e0c3ebe4fd4fbdc71620b8788 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Fri, 14 Jul 2023 15:55:51 -0400 Subject: [PATCH] maple_tree: Be more strict about locking Use lockdep to check the write path in the maple tree holds the lock in write mode. Introduce mt_write_lock_is_held() to check if the lock is held for writing. Update the necessary checks for rcu_dereference_protected() to use the new write lock check. Link: https://lkml.kernel.org/r/20230714195551.894800-5-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Linus Torvalds Cc: Oliver Sang Signed-off-by: Andrew Morton --- include/linux/maple_tree.h | 7 ++++++- lib/maple_tree.c | 10 ++++++++-- 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index e278b9598428..949f911bf955 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -185,13 +185,18 @@ typedef struct lockdep_map *lockdep_map_p; #define mt_lock_is_held(mt) \ (!(mt)->ma_external_lock || lock_is_held((mt)->ma_external_lock)) +#define mt_write_lock_is_held(mt) \ + (!(mt)->ma_external_lock || \ + lock_is_held_type((mt)->ma_external_lock, 0)) + #define mt_set_external_lock(mt, lock) \ (mt)->ma_external_lock = &(lock)->dep_map #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_lock_is_held(mt) 1 +#define mt_write_lock_is_held(mt) 1 #define mt_set_external_lock(mt, lock) do { } while (0) #define mt_on_stack(mt) do { } while (0) #endif diff --git a/lib/maple_tree.c b/lib/maple_tree.c index b6b3973897f0..3b6f8c8dac65 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -777,6 +777,12 @@ static inline void __rcu **ma_slots(struct maple_node *mn, enum maple_type mt) } } +static inline bool mt_write_locked(const struct maple_tree *mt) +{ + return mt_external_lock(mt) ? mt_write_lock_is_held(mt) : + lockdep_is_held(&mt->ma_lock); +} + static inline bool mt_locked(const struct maple_tree *mt) { return mt_external_lock(mt) ? mt_lock_is_held(mt) : @@ -792,7 +798,7 @@ static inline void *mt_slot(const struct maple_tree *mt, static inline void *mt_slot_locked(struct maple_tree *mt, void __rcu **slots, unsigned char offset) { - return rcu_dereference_protected(slots[offset], mt_locked(mt)); + return rcu_dereference_protected(slots[offset], mt_write_locked(mt)); } /* * mas_slot_locked() - Get the slot value when holding the maple tree lock. @@ -835,7 +841,7 @@ static inline void *mas_root(struct ma_state *mas) static inline void *mt_root_locked(struct maple_tree *mt) { - return rcu_dereference_protected(mt->ma_root, mt_locked(mt)); + return rcu_dereference_protected(mt->ma_root, mt_write_locked(mt)); } /* -- 2.25.1