[PATCH v3 07/14] yama: Remove redundant rcu_read_lock/unlock() in spin_lock

[pengdonglin]

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: Kees Cook <k...@kernel.org>
Cc: Paul Moore <p...@paul-moore.com>
Cc: James Morris <jmor...@namei.org>
Signed-off-by: pengdonglin <pengdong...@xiaomi.com>
Signed-off-by: pengdonglin <dolinux.p...@gmail.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