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From:   "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To:     linux-kernel@vger.kernel.org
Cc:     mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
        akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
        josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
        rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
        fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 19/27] rcu: Add diagnostics for rcutorture writer stall warning
Date:   Mon, 25 Jun 2018 17:35:05 -0700
In-Reply-To: <20180626003448.GA26209@linux.vnet.ibm.com>
References: <20180626003448.GA26209@linux.vnet.ibm.com>
Message-Id: <20180626003513.27812-19-paulmck@linux.vnet.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This commit adds any in-the-future ->gp_seq_needed fields to the
diagnostics for an rcutorture writer stall warning message.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c5fec335bc31..bc1ed77a3df9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -606,11 +606,32 @@ EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
  */
 void show_rcu_gp_kthreads(void)
 {
+	int cpu;
+	struct rcu_data *rdp;
+	struct rcu_node *rnp;
 	struct rcu_state *rsp;
 
 	for_each_rcu_flavor(rsp) {
 		pr_info("%s: wait state: %d ->state: %#lx\n",
 			rsp->name, rsp->gp_state, rsp->gp_kthread->state);
+		rcu_for_each_node_breadth_first(rsp, rnp) {
+			if (ULONG_CMP_GE(rsp->gp_seq, rnp->gp_seq_needed))
+				continue;
+			pr_info("\trcu_node %d:%d ->gp_seq %lu ->gp_seq_needed %lu\n",
+				rnp->grplo, rnp->grphi, rnp->gp_seq,
+				rnp->gp_seq_needed);
+			if (!rcu_is_leaf_node(rnp))
+				continue;
+			for_each_leaf_node_possible_cpu(rnp, cpu) {
+				rdp = per_cpu_ptr(rsp->rda, cpu);
+				if (rdp->gpwrap ||
+				    ULONG_CMP_GE(rsp->gp_seq,
+						 rdp->gp_seq_needed))
+					continue;
+				pr_info("\tcpu %d ->gp_seq_needed %lu\n",
+					cpu, rdp->gp_seq_needed);
+			}
+		}
 		/* sched_show_task(rsp->gp_kthread); */
 	}
 }
-- 
2.17.1