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

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Message-Id: <20250916044735.2316171-6-dolinux.peng@gmail.com>
Date: Tue, 16 Sep 2025 12:47:26 +0800
From: pengdonglin <dolinux.peng@...il.com>
To: tj@...nel.org,
	tony.luck@...el.com,
	jani.nikula@...ux.intel.com,
	ap420073@...il.com,
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Cc: bigeasy@...utronix.de,
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	paulmck@...nel.org,
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	linux-wireless@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	linux-s390@...r.kernel.org,
	cgroups@...r.kernel.org,
	pengdonglin <dolinux.peng@...il.com>,
	Holger Dengler <dengler@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	pengdonglin <pengdonglin@...omi.com>
Subject: [PATCH v3 05/14] s390/pkey: Remove redundant rcu_read_lock/unlock() in spin_lock

From: pengdonglin <pengdonglin@...omi.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@...ux.ibm.com>
Cc: Holger Dengler <dengler@...ux.ibm.com>
Cc: Vasily Gorbik <gor@...ux.ibm.com>
Cc: Alexander Gordeev <agordeev@...ux.ibm.com>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
Signed-off-by: pengdonglin <dolinux.peng@...il.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