Commit 0f9368b5 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Peter Zijlstra
Browse files

rwsem: Implement down_read_killable_nested 



In preparation for converting exec_update_mutex to a rwsem so that
multiple readers can execute in parallel and not deadlock, add
down_read_killable_nested.  This is needed so that kcmp_lock
can be converted from working on a mutexes to working on rw_semaphores.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/87o8jabqh3.fsf@x220.int.ebiederm.org
parent 34816d20

include/linux/rwsem.h

+2 −0
Original line number Diff line number Diff line
@@ -171,6 +171,7 @@ extern void downgrade_write(struct rw_semaphore *sem); 
 * See Documentation/locking/lockdep-design.rst for more details.)

 */

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

extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass);

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

extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass);

extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock);
@@ -191,6 +192,7 @@ extern void down_read_non_owner(struct rw_semaphore *sem); 
extern void up_read_non_owner(struct rw_semaphore *sem);

#else

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

# define down_read_killable_nested(sem, subclass)	down_read_killable(sem)

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

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

# define down_write_killable_nested(sem, subclass)	down_write_killable(sem)

kernel/locking/rwsem.c

+14 −0
Original line number Diff line number Diff line
@@ -1605,6 +1605,20 @@ void down_read_nested(struct rw_semaphore *sem, int subclass) 
}

EXPORT_SYMBOL(down_read_nested);



int down_read_killable_nested(struct rw_semaphore *sem, int subclass)

{

	might_sleep();

	rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);



	if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_killable)) {

		rwsem_release(&sem->dep_map, _RET_IP_);

		return -EINTR;

	}



	return 0;

}

EXPORT_SYMBOL(down_read_killable_nested);



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

{

	might_sleep();