[tip: core/rcu] rcu: Add ->rt_priority and ->gp_start to show_rcu_gp_kthreads() output

[tip-bot2 for Paul E. McKenney]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     e44111ed20d8b2d7b05b20d694358ae77d4e93e2
Gitweb:        https://git.kernel.org/tip/e44111ed20d8b2d7b05b20d694358ae77d4e93e2
Author:        Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate:    Fri, 02 Apr 2021 21:51:50 -07:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 10 May 2021 16:22:54 -07:00

rcu: Add ->rt_priority and ->gp_start to show_rcu_gp_kthreads() output

This commit adds ->rt_priority and ->gp_start to show_rcu_gp_kthreads()
output in order to better diagnose RCU priority boosting failures.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/tree_stall.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 59b95cc..fb47025 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -726,6 +726,7 @@ void show_rcu_gp_kthreads(void)
 	unsigned long j;
 	unsigned long ja;
 	unsigned long jr;
+	unsigned long js;
 	unsigned long jw;
 	struct rcu_data *rdp;
 	struct rcu_node *rnp;
@@ -734,11 +735,12 @@ void show_rcu_gp_kthreads(void)
 	j = jiffies;
 	ja = j - data_race(rcu_state.gp_activity);
 	jr = j - data_race(rcu_state.gp_req_activity);
+	js = j - data_race(rcu_state.gp_start);
 	jw = j - data_race(rcu_state.gp_wake_time);
-	pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
+	pr_info("%s: wait state: %s(%d) ->state: %#lx ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
 		rcu_state.name, gp_state_getname(rcu_state.gp_state),
-		rcu_state.gp_state, t ? t->state : 0x1ffffL,
-		ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
+		rcu_state.gp_state, t ? t->state : 0x1ffffL, t ? t->rt_priority : 0xffU,
+		js, ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
 		(long)data_race(rcu_state.gp_seq),
 		(long)data_race(rcu_get_root()->gp_seq_needed),
 		data_race(rcu_state.gp_flags));