linux-kernel - [PATCH tip/core/rcu 11/11] rcu/nocb: Print gp/cb kthread hierarchy if dump

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Message-Id: <20190801225028.18225-11-paulmck@linux.ibm.com>
Date:   Thu,  1 Aug 2019 15:50:28 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 11/11] rcu/nocb: Print gp/cb kthread hierarchy if dump_tree

This commit causes the no-CBs grace-period/callback hierarchy to be
printed to the console when the dump_tree kernel boot parameter is set.

Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.com>
---
 kernel/rcu/tree_plugin.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 80b27a9f306d..0a3f8680b450 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2135,6 +2135,7 @@ module_param(rcu_nocb_gp_stride, int, 0444);
 static void __init rcu_organize_nocb_kthreads(void)
 {
 	int cpu;
+	bool firsttime = true;
 	int ls = rcu_nocb_gp_stride;
 	int nl = 0;  /* Next GP kthread. */
 	struct rcu_data *rdp;
@@ -2160,10 +2161,15 @@ static void __init rcu_organize_nocb_kthreads(void)
 			nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls;
 			rdp->nocb_gp_rdp = rdp;
 			rdp_gp = rdp;
+			if (!firsttime && dump_tree)
+				pr_cont("\n");
+			firsttime = false;
+			pr_alert("%s: No-CB GP kthread CPU %d:", __func__, cpu);
 		} else {
 			/* Another CB kthread, link to previous GP kthread. */
 			rdp->nocb_gp_rdp = rdp_gp;
 			rdp_prev->nocb_next_cb_rdp = rdp;
+			pr_alert(" %d", cpu);
 		}
 		rdp_prev = rdp;
 	}
-- 
2.17.1