rwsem: Provide down_read_non_owner() and up_read_non_owner() for -RT

The rwsem implementation on -RT allows multiple reader and there is no
owner tracking anymore.
We can provide down_read_non_owner() and up_read_non_owner() by skipping
the owner check bits which are only available in the !RT implementation.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/locking/rwsem.c

@@ -1616,15 +1616,15 @@ void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
 }
 EXPORT_SYMBOL(_down_write_nest_lock);
 
-#ifndef CONFIG_PREEMPT_RT
 void down_read_non_owner(struct rw_semaphore *sem)
 {
 	might_sleep();
 	__down_read(sem);
+#ifndef CONFIG_PREEMPT_RT
 	__rwsem_set_reader_owned(sem, NULL);
+#endif
 }
 EXPORT_SYMBOL(down_read_non_owner);
-#endif
 
 void down_write_nested(struct rw_semaphore *sem, int subclass)
 {
@@ -1649,13 +1649,13 @@ int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass)
 }
 EXPORT_SYMBOL(down_write_killable_nested);
 
-#ifndef CONFIG_PREEMPT_RT
 void up_read_non_owner(struct rw_semaphore *sem)
 {
+#ifndef CONFIG_PREEMPT_RT
 	DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
+#endif
 	__up_read(sem);
 }
 EXPORT_SYMBOL(up_read_non_owner);
-#endif
 
 #endif