sched/fair: Remove superfluous rcu_read_lock()

With fair switched to rcu_dereference_all() validation, having IRQ or
preemption disabled is sufficient, remove the rcu_read_lock()
clutter.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20251127154725.647502625@infradead.org

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 44a359d6a299f1837cb3166d9fbe2d019efd4beb..496a30a418540f6a765206a0205fd8be8f03c4a4 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12856,21 +12856,16 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
         */
        rq_unpin_lock(this_rq, rf);
 
-       rcu_read_lock();
        sd = rcu_dereference_sched_domain(this_rq->sd);
-       if (!sd) {
-               rcu_read_unlock();
+       if (!sd)
                goto out;
-       }
 
        if (!get_rd_overloaded(this_rq->rd) ||
            this_rq->avg_idle < sd->max_newidle_lb_cost) {
 
                update_next_balance(sd, &next_balance);
-               rcu_read_unlock();
                goto out;
        }
-       rcu_read_unlock();
 
        /*
         * Include sched_balance_update_blocked_averages() in the cost
@@ -12883,7 +12878,6 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
        rq_modified_clear(this_rq);
        raw_spin_rq_unlock(this_rq);
 
-       rcu_read_lock();
        for_each_domain(this_cpu, sd) {
                u64 domain_cost;
 
@@ -12933,7 +12927,6 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
                if (pulled_task || !continue_balancing)
                        break;
        }
-       rcu_read_unlock();
 
        raw_spin_rq_lock(this_rq);