From: Paul E. McKenney <paulmck@kernel.org>
Date: Wed, 25 May 2022 03:36:08 +0000 (-0700)
Subject: rcu-tasks: Flag offline CPUs in RCU Tasks Trace stall warnings
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c8c03ad9d7cd694b88ab8db4199b4e4d3c6cc5aa;p=linux.git

rcu-tasks: Flag offline CPUs in RCU Tasks Trace stall warnings

This commit tags offline CPUs with "(offline)" in RCU Tasks Trace CPU
stall warnings.  This is 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 1cfbebf2b5977..93096188d3631 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1502,14 +1502,14 @@ static void show_stalled_task_trace(struct task_struct *t, bool *firstreport)
 			 ".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",
+		pr_alert("P%d: %c%c%c nesting: %d%c cpu: %d%s\n",
 			 t->pid,
 			 ".I"[trc_rdr.ipi_to_cpu >= 0],
 			 ".i"[is_idle_tsk],
 			 ".N"[cpu >= 0 && tick_nohz_full_cpu(cpu)],
 			 trc_rdr.nesting,
 			 " N"[!!trc_rdr.needqs],
-			 cpu);
+			 cpu, cpu_online(cpu) ? "" : "(offline)");
 	sched_show_task(t);
 }