[PATCH rcu 15/32] rcu-tasks: Make RCU Tasks Trace stall warnings print full .b.need_qs field

Paul E. McKenney
2022-06-20T22:55:56Z

Currently, the RCU Tasks Trace CPU stall warning simply indicates
whether or not the .b.need_qs field is zero. This commit shows the
three permitted values and flags other values with either "!" or "?".
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>
---
kernel/rcu/tasks.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 93096188d3631..5eefbab7f2edb 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1502,13 +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%s\n",
+ pr_alert("P%d: %c%c%c nesting: %d%c%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],
+ " !CN"[trc_rdr.needqs & 0x3],
+ " ?"[trc_rdr.needqs > 0x3],
cpu, cpu_online(cpu) ? "" : "(offline)");
sched_show_task(t);
}
--
2.31.1.189.g2e36527f23