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

[Harald Freudenberger]

On 2025-09-16 06:47, pengdonglin wrote:

From: pengdonglin <pengdong...@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 <fre...@linux.ibm.com>
Cc: Holger Dengler <deng...@linux.ibm.com>
Cc: Vasily Gorbik <g...@linux.ibm.com>
Cc: Alexander Gordeev <agord...@linux.ibm.com>
Signed-off-by: pengdonglin <pengdong...@xiaomi.com>
Signed-off-by: pengdonglin <dolinux.p...@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);

Acked-by: Harald Freudenberger <fre...@linux.ibm.com>