From: Paul E. McKenney <paulmck@kernel.org>
Date: Tue, 24 May 2022 23:05:15 +0000 (-0700)
Subject: rcu-tasks: Add slow-IPI indicator to RCU Tasks Trace stall warnings
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9f3eb5fb8e468d3c3a6073d0c816405fa73c8038;p=linux.git

rcu-tasks: Add slow-IPI indicator to RCU Tasks Trace stall warnings

This commit adds a "I" indicator to the RCU Tasks Trace CPU stall
warning when an IPI directed to a task has thus far failed to arrive.
This serves as a debugging aid.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
---

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 6b44c69eeca88..1cfbebf2b5977 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1497,8 +1497,9 @@ static void show_stalled_task_trace(struct task_struct *t, bool *firstreport)
 	}
 	cpu = task_cpu(t);
 	if (!task_call_func(t, trc_check_slow_task, &trc_rdr))
-		pr_alert("P%d: %c\n",
+		pr_alert("P%d: %c%c\n",
 			 t->pid,
+			 ".I"[t->trc_ipi_to_cpu >= 0],
 			 ".i"[is_idle_tsk]);
 	else
 		pr_alert("P%d: %c%c%c nesting: %d%c cpu: %d\n",