Messages in this thread Patch in this message | | | From | paulmck@kernel ... | Subject | [PATCH tip/core/rcu 09/21] rcu/nocb: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY | Date | Tue, 5 Jan 2021 20:48:41 -0800 |
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From: Frederic Weisbecker <frederic@kernel.org>
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: Paul E. McKenney <paulmck@kernel.org> Tested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/tree_plugin.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c88ad62..35dc9b3 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -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; } -- 2.9.5
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