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cgroup/cpuset: Remove redundant rcu_read_lock/unlock() in spin_lock

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Since commit a8bb74acd8 ("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: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
Signed-off-by: pengdonglin <dolinux.peng@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
pengdonglin 2025-09-16 12:47:30 +08:00 committed by Tejun Heo
parent 3ee4211ef8
commit 58ab6d25a1
1 changed files with 0 additions and 6 deletions
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6
kernel/cgroup/cpuset.c
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@ -4107,7 +4107,6 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
struct cpuset *cs;
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
cs = task_cs(tsk);
if (cs != &top_cpuset)
@ -4129,7 +4128,6 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
cpumask_copy(pmask, possible_mask);
}
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
}
@ -4202,9 +4200,7 @@ nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
unsigned long flags;
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
guarantee_online_mems(task_cs(tsk), &mask);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
return mask;
@ -4299,10 +4295,8 @@ bool cpuset_current_node_allowed(int node, gfp_t gfp_mask)
/* Not hardwall and node outside mems_allowed: scan up cpusets */
spin_lock_irqsave(&callback_lock, flags);
rcu_read_lock();
cs = nearest_hardwall_ancestor(task_cs(current));
allowed = node_isset(node, cs->mems_allowed);
rcu_read_unlock();
spin_unlock_irqrestore(&callback_lock, flags);
return allowed;