Commit 82e44569 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Diagnose extended sync_rcu_do_polled_gp() loops 



This commit dumps out state when the sync_rcu_do_polled_gp() function
loops more than expected.  This is a debugging aid.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent ef4f9d9b

kernel/rcu/tree_exp.h

+6 −1
Original line number Diff line number Diff line
@@ -970,6 +970,7 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); 
static void sync_rcu_do_polled_gp(struct work_struct *wp)

{

	unsigned long flags;

	int i = 0;

	struct rcu_node *rnp = container_of(wp, struct rcu_node, exp_poll_wq);

	unsigned long s;
@@ -979,8 +980,12 @@ static void sync_rcu_do_polled_gp(struct work_struct *wp) 
	raw_spin_unlock_irqrestore(&rnp->exp_poll_lock, flags);

	if (s == RCU_GET_STATE_COMPLETED)

		return;

	while (!poll_state_synchronize_rcu(s))

	while (!poll_state_synchronize_rcu(s)) {

		synchronize_rcu_expedited();

		if (i == 10 || i == 20)

			pr_info("%s: i = %d s = %lx gp_seq_polled = %lx\n", __func__, i, s, READ_ONCE(rcu_state.gp_seq_polled));

		i++;

	}

	raw_spin_lock_irqsave(&rnp->exp_poll_lock, flags);

	s = rnp->exp_seq_poll_rq;

	if (poll_state_synchronize_rcu(s))