locking/percpu-rwsem: Export symbols for locktorture

This commit exports percpu_down_read(), percpu_down_write(),
__percpu_init_rwsem(), percpu_up_read(), and percpu_up_write() to allow
locktorture to test them when built as a module.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

kernel/locking/percpu-rwsem.c

@@ -22,6 +22,7 @@ int __percpu_init_rwsem(struct percpu_rw_semaphore *brw,
 	init_waitqueue_head(&brw->write_waitq);
 	return 0;
 }
+EXPORT_SYMBOL_GPL(__percpu_init_rwsem);
 
 void percpu_free_rwsem(struct percpu_rw_semaphore *brw)
 {
@@ -87,6 +88,7 @@ void percpu_down_read(struct percpu_rw_semaphore *brw)
 	/* avoid up_read()->rwsem_release() */
 	__up_read(&brw->rw_sem);
 }
+EXPORT_SYMBOL_GPL(percpu_down_read);
 
 int percpu_down_read_trylock(struct percpu_rw_semaphore *brw)
 {
@@ -112,6 +114,7 @@ void percpu_up_read(struct percpu_rw_semaphore *brw)
 	if (atomic_dec_and_test(&brw->slow_read_ctr))
 		wake_up_all(&brw->write_waitq);
 }
+EXPORT_SYMBOL_GPL(percpu_up_read);
 
 static int clear_fast_ctr(struct percpu_rw_semaphore *brw)
 {
@@ -163,6 +166,7 @@ void percpu_down_write(struct percpu_rw_semaphore *brw)
 	/* wait for all readers to complete their percpu_up_read() */
 	wait_event(brw->write_waitq, !atomic_read(&brw->slow_read_ctr));
 }
+EXPORT_SYMBOL_GPL(percpu_down_write);
 
 void percpu_up_write(struct percpu_rw_semaphore *brw)
 {
@@ -176,3 +180,4 @@ void percpu_up_write(struct percpu_rw_semaphore *brw)
 	/* the last writer unblocks update_fast_ctr() */
 	atomic_dec(&brw->write_ctr);
 }
+EXPORT_SYMBOL_GPL(percpu_up_write);