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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 18/27] rcu: Add comment to the last sleep in the rcu tasks loop
Date:   Mon, 25 Jun 2018 17:35:04 -0700
In-Reply-To: <20180626003448.GA26209@linux.vnet.ibm.com>
References: <20180626003448.GA26209@linux.vnet.ibm.com>
Message-Id: <20180626003513.27812-18-paulmck@linux.vnet.ibm.com>
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From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

At the end of rcu_tasks_kthread() there's a lonely
schedule_timeout_uninterruptible() call with no apparent rationale for
its existence. But there is. It is to keep the thread from going into
a tight loop if there's some anomaly. That really needs a comment.

Link: http://lkml.kernel.org/r/20180524223839.GU3803@linux.vnet.ibm.com
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/update.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 4c7c49c106ee..39cb23d22109 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -814,6 +814,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
 			list = next;
 			cond_resched();
 		}
+		/* Paranoid sleep to keep this from entering a tight loop */
 		schedule_timeout_uninterruptible(HZ/10);
 	}
 }
-- 
2.17.1