Commit 19a462f0 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

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: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oliver Sang <oliver.sang@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 02fdb25f

include/linux/maple_tree.h

+6 −1
Original line number Diff line number Diff line
@@ -185,6 +185,10 @@ 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
@@ -192,6 +196,7 @@ typedef struct lockdep_map *lockdep_map_p; 
#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)

#define mt_on_stack(mt)			do { } while (0)

#endif

lib/maple_tree.c

+8 −2
Original line number Diff line number Diff line
@@ -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));

}



/*