From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, "Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 11/12] rcu: Diagnose extended sync_rcu_do_polled_gp() loops
Date: Mon, 20 Jun 2022 15:51:27 -0700 [thread overview]
Message-ID: <20220620225128.3842050-11-paulmck@kernel.org> (raw)
In-Reply-To: <20220620224943.GA3841634@paulmck-ThinkPad-P17-Gen-1>
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: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree_exp.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index f05a15b11fa0c..4c7037b507032 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -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))
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2022-06-20 22:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 22:49 [PATCH rcu 0/12] Polled grace-period updates for v5.20 Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 01/12] rcu: Make normal polling GP be more precise about sequence numbers Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 02/12] rcu: Provide a get_completed_synchronize_rcu() function Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 03/12] rcutorture: Validate get_completed_synchronize_rcu() Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 04/12] rcu: Switch polled grace-period APIs to ->gp_seq_polled Paul E. McKenney
2022-07-21 0:53 ` Boqun Feng
2022-07-21 1:04 ` Paul E. McKenney
2022-07-21 1:51 ` Boqun Feng
2022-07-21 4:47 ` Paul E. McKenney
2022-07-21 5:49 ` Boqun Feng
2022-07-22 1:03 ` Paul E. McKenney
2022-07-21 1:56 ` Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 05/12] rcu: Make polled grace-period API account for expedited grace periods Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 06/12] rcu: Make Tiny RCU grace periods visible to polled APIs Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 07/12] rcutorture: Verify that polled GP API sees synchronous grace periods Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 08/12] rcu: Add polled expedited grace-period primitives Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 09/12] rcutorture: Test " Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 10/12] rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings Paul E. McKenney
2022-06-20 22:51 ` Paul E. McKenney [this message]
2022-06-20 22:51 ` [PATCH rcu 12/12] rcu: Add irqs-disabled indicator to " Paul E. McKenney
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