rcu: Move wakeup out from under rnp->lock

This patch removes a potential deadlock hazard by moving the
wake_up_process() in rcu_spawn_gp_kthread() out from under rnp->lock.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 40940b0d03109c44c782fbccfd93b0079a7cea65..87b604d0b0d22d67ffe7cd6132d9b5e667e5f56b 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4319,8 +4319,8 @@ static int __init rcu_spawn_gp_kthread(void)
                        sp.sched_priority = kthread_prio;
                        sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
                }
-               wake_up_process(t);
                raw_spin_unlock_irqrestore(&rnp->lock, flags);
+               wake_up_process(t);
        }
        rcu_spawn_nocb_kthreads();
        rcu_spawn_boost_kthreads();