linux-kernel - [PATCH tip/core/rcu 19/22] rcu: Add up-tree information to dump_blkd

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Message-Id: <20180626171048.2181-19-paulmck@linux.vnet.ibm.com>
Date:   Tue, 26 Jun 2018 10:10:45 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     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.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 19/22] rcu: Add up-tree information to dump_blkd_tasks() diagnostics

This commit updates dump_blkd_tasks() to print out quiescent-state
bitmasks for the rcu_node structures further up the tree.  This
information helps debugging of interactions between CPU-hotplug
operations and RCU grace-period initialization.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/tree_plugin.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 6b85ce936ad4..f45ff97b0d51 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -858,13 +858,15 @@ static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck)
 {
 	int i;
 	struct list_head *lhp;
+	struct rcu_node *rnp1;
 
 	raw_lockdep_assert_held_rcu_node(rnp);
-	pr_info("%s: grp: %d-%d level: %d ->gp_seq %#lx ->completedqs %#lx\n",
+	pr_info("%s: grp: %d-%d level: %d ->gp_seq %ld ->completedqs %ld\n",
 		__func__, rnp->grplo, rnp->grphi, rnp->level,
-		rnp->gp_seq, rnp->completedqs);
-	pr_info("%s: ->qsmask %#lx ->qsmaskinit %#lx ->qsmaskinitnext %#lx\n",
-		__func__, rnp->qsmask, rnp->qsmaskinit, rnp->qsmaskinitnext);
+		(long)rnp->gp_seq, (long)rnp->completedqs);
+	for (rnp1 = rnp; rnp1; rnp1 = rnp1->parent)
+		pr_info("%s: %d:%d ->qsmask %#lx ->qsmaskinit %#lx ->qsmaskinitnext %#lx\n",
+			__func__, rnp1->grplo, rnp1->grphi, rnp1->qsmask, rnp1->qsmaskinit, rnp1->qsmaskinitnext);
 	pr_info("%s: ->gp_tasks %p ->boost_tasks %p ->exp_tasks %p\n",
 		__func__, rnp->gp_tasks, rnp->boost_tasks, rnp->exp_tasks);
 	pr_info("%s: ->blkd_tasks", __func__);
-- 
2.17.1