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Commit 1b963c81 authored by Jiri Kosina's avatar Jiri Kosina Committed by Linus Torvalds
Browse files

lockdep, rwsem: provide down_write_nest_lock() 



down_write_nest_lock() provides a means to annotate locking scenario
where an outer lock is guaranteed to serialize the order nested locks
are being acquired.

This is analogoue to already existing mutex_lock_nest_lock() and
spin_lock_nest_lock().

Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mel Gorman <mel@csn.ul.ie>
Tested-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fef6c12e

include/linux/lockdep.h

+3 −0
Original line number Diff line number Diff line
@@ -524,14 +524,17 @@ static inline void print_irqtrace_events(struct task_struct *curr) 
#ifdef CONFIG_DEBUG_LOCK_ALLOC

# ifdef CONFIG_PROVE_LOCKING

#  define rwsem_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 2, NULL, i)

#  define rwsem_acquire_nest(l, s, t, n, i)	lock_acquire(l, s, t, 0, 2, n, i)

#  define rwsem_acquire_read(l, s, t, i)	lock_acquire(l, s, t, 1, 2, NULL, i)

# else

#  define rwsem_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 1, NULL, i)

#  define rwsem_acquire_nest(l, s, t, n, i)	lock_acquire(l, s, t, 0, 1, n, i)

#  define rwsem_acquire_read(l, s, t, i)	lock_acquire(l, s, t, 1, 1, NULL, i)

# endif

# define rwsem_release(l, n, i)			lock_release(l, n, i)

#else

# define rwsem_acquire(l, s, t, i)		do { } while (0)

# define rwsem_acquire_nest(l, s, t, n, i)	do { } while (0)

# define rwsem_acquire_read(l, s, t, i)		do { } while (0)

# define rwsem_release(l, n, i)			do { } while (0)

#endif

include/linux/rwsem.h

+9 −0
Original line number Diff line number Diff line
@@ -125,8 +125,17 @@ extern void downgrade_write(struct rw_semaphore *sem); 
 */

extern void down_read_nested(struct rw_semaphore *sem, int subclass);

extern void down_write_nested(struct rw_semaphore *sem, int subclass);

extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock);



# define down_write_nest_lock(sem, nest_lock)			\

do {								\

	typecheck(struct lockdep_map *, &(nest_lock)->dep_map);	\

	_down_write_nest_lock(sem, &(nest_lock)->dep_map);	\

} while (0);



#else

# define down_read_nested(sem, subclass)		down_read(sem)

# define down_write_nest_lock(sem, nest_lock)	down_read(sem)

# define down_write_nested(sem, subclass)	down_write(sem)

#endif

kernel/rwsem.c

+10 −0
Original line number Diff line number Diff line
@@ -116,6 +116,16 @@ void down_read_nested(struct rw_semaphore *sem, int subclass) 


EXPORT_SYMBOL(down_read_nested);



void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)

{

	might_sleep();

	rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_);



	LOCK_CONTENDED(sem, __down_write_trylock, __down_write);

}



EXPORT_SYMBOL(_down_write_nest_lock);



void down_write_nested(struct rw_semaphore *sem, int subclass)

{

	might_sleep();