rcu/tree: Fix SCHED_FIFO params

[ Upstream commit 130d9c331bc59a8733b47c58ef197a2b1fa3ed43 ]

A rather embarrasing mistake had us call sched_setscheduler() before
initializing the parameters passed to it.

Fixes: 1a763fd7c633 ("rcu/tree: Call setschedule() gp ktread to SCHED_FIFO outside of atomic region")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 32ea75acba144108363ddd7ed25d048d5fe72689..affa7aae758f3478f32358e1ca712bab158b4cd2 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3123,13 +3123,13 @@ static int __init rcu_spawn_gp_kthread(void)
        t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name);
        if (WARN_ONCE(IS_ERR(t), "%s: Could not start grace-period kthread, OOM is now expected behavior\n", __func__))
                return 0;
-       if (kthread_prio)
+       if (kthread_prio) {
+               sp.sched_priority = kthread_prio;
                sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
+       }
        rnp = rcu_get_root();
        raw_spin_lock_irqsave_rcu_node(rnp, flags);
        rcu_state.gp_kthread = t;
-       if (kthread_prio)
-               sp.sched_priority = kthread_prio;
        raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
        wake_up_process(t);
        rcu_spawn_nocb_kthreads();