Commit 314202f8 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
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rcu/nocb: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY 



This commit flushes the bypass queue and sets state to avoid its being
refilled before switching to the final de-offloaded state.  To avoid
refilling, this commit sets SEGCBLIST_SOFTIRQ_ONLY before re-enabling
IRQs.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Tested-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 69cdea87

kernel/rcu/tree_plugin.h

+10 −1
Original line number Diff line number Diff line
@@ -2339,12 +2339,21 @@ static int __rcu_nocb_rdp_deoffload(struct rcu_data *rdp) 
	swait_event_exclusive(rdp->nocb_state_wq,

			      !rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB |

							SEGCBLIST_KTHREAD_GP));

	/* Make sure nocb timer won't stay around */

	rcu_nocb_lock_irqsave(rdp, flags);

	/* Make sure nocb timer won't stay around */

	WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_OFF);

	rcu_nocb_unlock_irqrestore(rdp, flags);

	del_timer_sync(&rdp->nocb_timer);



	/*

	 * Flush bypass. While IRQs are disabled and once we set

	 * SEGCBLIST_SOFTIRQ_ONLY, no callback is supposed to be

	 * enqueued on bypass.

	 */

	rcu_nocb_lock_irqsave(rdp, flags);

	rcu_nocb_flush_bypass(rdp, NULL, jiffies);

	rcu_nocb_unlock_irqrestore(rdp, flags);



	return ret;

}