>From c214e54a20258ca9c3ff787b435b04a1d900ad21 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Wed, 5 Jul 2023 12:37:47 -0400 Subject: [PATCH 1/2] 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. Signed-off-by: Liam R. Howlett --- include/linux/maple_tree.h | 12 ++++++++++-- lib/maple_tree.c | 10 ++++++++-- 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index 295548cca8b3..f856d67a5d7c 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -184,12 +184,20 @@ 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_write_lock_is_held(mt) \ + (!(mt)->ma_external_lock || \ + lock_is_held_type((mt)->ma_external_lock, 0)) + +#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 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) #endif diff --git a/lib/maple_tree.c b/lib/maple_tree.c index bfffbb7cab26..1c9eab89e34b 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -804,6 +804,12 @@ 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) : @@ -819,7 +825,7 @@ 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. @@ -862,7 +868,7 @@ 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)); } /* -- 2.39.2