linux-kernel - [PATCH v3 07/14] yama: Remove redundant rcu_read_lock/unlock() in spin

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Message-Id: <20250916044735.2316171-8-dolinux.peng@gmail.com>
Date: Tue, 16 Sep 2025 12:47:28 +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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	kees@...nel.org
Cc: bigeasy@...utronix.de,
	hdanton@...a.com,
	paulmck@...nel.org,
	linux-kernel@...r.kernel.org,
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	pengdonglin <dolinux.peng@...il.com>,
	Paul Moore <paul@...l-moore.com>,
	James Morris <jmorris@...ei.org>,
	pengdonglin <pengdonglin@...omi.com>
Subject: [PATCH v3 07/14] yama: 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: Kees Cook <kees@...nel.org>
Cc: Paul Moore <paul@...l-moore.com>
Cc: James Morris <jmorris@...ei.org>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
Signed-off-by: pengdonglin <dolinux.peng@...il.com>
---
 security/yama/yama_lsm.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 3d064dd4e03f..60d38deb181b 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -117,14 +117,12 @@ static void yama_relation_cleanup(struct work_struct *work)
 	struct ptrace_relation *relation;
 
 	spin_lock(&ptracer_relations_lock);
-	rcu_read_lock();
 	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
 		if (relation->invalid) {
 			list_del_rcu(&relation->node);
 			kfree_rcu(relation, rcu);
 		}
 	}
-	rcu_read_unlock();
 	spin_unlock(&ptracer_relations_lock);
 }
 
@@ -152,7 +150,6 @@ static int yama_ptracer_add(struct task_struct *tracer,
 	added->invalid = false;
 
 	spin_lock(&ptracer_relations_lock);
-	rcu_read_lock();
 	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
 		if (relation->invalid)
 			continue;
@@ -166,7 +163,6 @@ static int yama_ptracer_add(struct task_struct *tracer,
 	list_add_rcu(&added->node, &ptracer_relations);
 
 out:
-	rcu_read_unlock();
 	spin_unlock(&ptracer_relations_lock);
 	return 0;
 }
-- 
2.34.1