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maple_tree: Be more strict about locking

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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 <Liam.Howlett@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oliver Sang <oliver.sang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2023-07-14 15:55:51 -04:00 committed by Andrew Morton
parent 02fdb25fb4
commit 19a462f06e
2 changed files with 14 additions and 3 deletions
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7
include/linux/maple_tree.h
View file

@ -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

10
lib/maple_tree.c
View file

@ -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));
}
/*