[PATCH v3 05/14] s390/pkey: Remove redundant rcu_read_lock/unlock() in spin_lock

[pengdonglin]

From: pengdonglin <pengdonglin at xiaomi.com>

Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().

There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().

Simplify the code and remove the inner rcu_read_lock() invocation.

Cc: Harald Freudenberger <freude at linux.ibm.com>
Cc: Holger Dengler <dengler at linux.ibm.com>
Cc: Vasily Gorbik <gor at linux.ibm.com>
Cc: Alexander Gordeev <agordeev at linux.ibm.com>
Signed-off-by: pengdonglin <pengdonglin at xiaomi.com>
Signed-off-by: pengdonglin <dolinux.peng at gmail.com>
---
 drivers/s390/crypto/pkey_base.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/s390/crypto/pkey_base.c b/drivers/s390/crypto/pkey_base.c
index b15741461a63..4c4a9feecccc 100644
--- a/drivers/s390/crypto/pkey_base.c
+++ b/drivers/s390/crypto/pkey_base.c
@@ -48,16 +48,13 @@ int pkey_handler_register(struct pkey_handler *handler)
 
 	spin_lock(&handler_list_write_lock);
 
-	rcu_read_lock();
 	list_for_each_entry_rcu(h, &handler_list, list) {
 		if (h == handler) {
-			rcu_read_unlock();
 			spin_unlock(&handler_list_write_lock);
 			module_put(handler->module);
 			return -EEXIST;
 		}
 	}
-	rcu_read_unlock();
 
 	list_add_rcu(&handler->list, &handler_list);
 	spin_unlock(&handler_list_write_lock);
-- 
2.34.1