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Commit f8319483 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Dave Chinner
Browse files

locking/lockdep: Provide a type check for lock_is_held 



Christoph requested lockdep_assert_held() variants that distinguish
between held-for-read or held-for-write.

Provide:

  int lock_is_held_type(struct lockdep_map *lock, int read)

which takes the same argument as lock_acquire(.read) and matches it to
the held_lock instance.

Use of this function should be gated by the debug_locks variable. When
that is 0 the return value of the lock_is_held_type() function is
undefined. This is done to allow both negative and positive tests for
holding locks.

By default we provide (positive) lockdep_assert_held{,_exclusive,_read}()
macros.

Requested-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarJens Axboe <axboe@fb.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent 38161995

include/linux/lockdep.h

+23 −2
Original line number Diff line number Diff line
@@ -338,9 +338,18 @@ extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
extern void lock_release(struct lockdep_map *lock, int nested,

			 unsigned long ip);



#define lockdep_is_held(lock)	lock_is_held(&(lock)->dep_map)

/*

 * Same "read" as for lock_acquire(), except -1 means any.

 */

extern int lock_is_held_type(struct lockdep_map *lock, int read);



static inline int lock_is_held(struct lockdep_map *lock)

{

	return lock_is_held_type(lock, -1);

}



extern int lock_is_held(struct lockdep_map *lock);

#define lockdep_is_held(lock)		lock_is_held(&(lock)->dep_map)

#define lockdep_is_held_type(lock, r)	lock_is_held_type(&(lock)->dep_map, (r))



extern void lock_set_class(struct lockdep_map *lock, const char *name,

			   struct lock_class_key *key, unsigned int subclass,
@@ -372,6 +381,14 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie); 
		WARN_ON(debug_locks && !lockdep_is_held(l));	\

	} while (0)



#define lockdep_assert_held_exclusive(l)	do {			\

		WARN_ON(debug_locks && !lockdep_is_held_type(l, 0));	\

	} while (0)



#define lockdep_assert_held_read(l)	do {				\

		WARN_ON(debug_locks && !lockdep_is_held_type(l, 1));	\

	} while (0)



#define lockdep_assert_held_once(l)	do {				\

		WARN_ON_ONCE(debug_locks && !lockdep_is_held(l));	\

	} while (0)
@@ -428,7 +445,11 @@ struct lock_class_key { }; 


#define lockdep_depth(tsk)	(0)



#define lockdep_is_held_type(l, r)		(1)



#define lockdep_assert_held(l)			do { (void)(l); } while (0)

#define lockdep_assert_held_exclusive(l)	do { (void)(l); } while (0)

#define lockdep_assert_held_read(l)		do { (void)(l); } while (0)

#define lockdep_assert_held_once(l)		do { (void)(l); } while (0)



#define lockdep_recursing(tsk)			(0)

kernel/locking/lockdep.c

+12 −8
Original line number Diff line number Diff line
@@ -3188,7 +3188,7 @@ print_lock_nested_lock_not_held(struct task_struct *curr, 
	return 0;

}



static int __lock_is_held(struct lockdep_map *lock);

static int __lock_is_held(struct lockdep_map *lock, int read);



/*

 * This gets called for every mutex_lock*()/spin_lock*() operation.
@@ -3329,7 +3329,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
	}

	chain_key = iterate_chain_key(chain_key, class_idx);



	if (nest_lock && !__lock_is_held(nest_lock))

	if (nest_lock && !__lock_is_held(nest_lock, -1))

		return print_lock_nested_lock_not_held(curr, hlock, ip);



	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
@@ -3576,7 +3576,7 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) 
	return 1;

}



static int __lock_is_held(struct lockdep_map *lock)

static int __lock_is_held(struct lockdep_map *lock, int read)

{

	struct task_struct *curr = current;

	int i;
@@ -3584,8 +3584,12 @@ static int __lock_is_held(struct lockdep_map *lock) 
	for (i = 0; i < curr->lockdep_depth; i++) {

		struct held_lock *hlock = curr->held_locks + i;



		if (match_held_lock(hlock, lock))

		if (match_held_lock(hlock, lock)) {

			if (read == -1 || hlock->read == read)

				return 1;



			return 0;

		}

	}



	return 0;
@@ -3769,7 +3773,7 @@ void lock_release(struct lockdep_map *lock, int nested, 
}

EXPORT_SYMBOL_GPL(lock_release);



int lock_is_held(struct lockdep_map *lock)

int lock_is_held_type(struct lockdep_map *lock, int read)

{

	unsigned long flags;

	int ret = 0;
@@ -3781,13 +3785,13 @@ int lock_is_held(struct lockdep_map *lock) 
	check_flags(flags);



	current->lockdep_recursion = 1;

	ret = __lock_is_held(lock);

	ret = __lock_is_held(lock, read);

	current->lockdep_recursion = 0;

	raw_local_irq_restore(flags);



	return ret;

}

EXPORT_SYMBOL_GPL(lock_is_held);

EXPORT_SYMBOL_GPL(lock_is_held_type);



struct pin_cookie lock_pin_lock(struct lockdep_map *lock)

{