[PATCH rcu 20/32] rcu-tasks: Add blocked-task indicator to RCU Tasks Trace stall warnings

Paul E. McKenney
2022-06-20T22:54:42Z

This commit adds a "B" indicator to the RCU Tasks Trace CPU stall warning
when the task has blocked within its current read-side critical section.
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>
---
kernel/rcu/tasks.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index eb87a759ef0b0..6f4b89f9517ef 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1536,11 +1536,12 @@ 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%c cpu: %d%s\n",
+ pr_alert("P%d: %c%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)],
+ ".B"[!!data_race(t->trc_reader_special.b.blocked)],
trc_rdr.nesting,
" !CN"[trc_rdr.needqs & 0x3],
" ?"[trc_rdr.needqs > 0x3],
--
2.31.1.189.g2e36527f23