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From: Frederic Weisbecker <frederic@kernel.org>
To: "Paul E . McKenney" <paulmck@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	Neeraj Upadhyay <neeraju@codeaurora.org>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: [PATCH 2/2] rcu: Remove needless preemption disablement in rcu_all_qs()
Date: Tue,  6 Jul 2021 01:43:44 +0200	[thread overview]
Message-ID: <20210705234344.104239-2-frederic@kernel.org> (raw)
In-Reply-To: <20210705234344.104239-1-frederic@kernel.org>

The preemption is already disabled when we write rcu_data.rcu_urgent_qs.
We can use __this_cpu_write() directly, although that path is mostly
used when CONFIG_PREEMPT=n.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
---
 kernel/rcu/tree_plugin.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 27b74352cccf..38b3d01424d7 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -871,7 +871,7 @@ void rcu_all_qs(void)
 		preempt_enable();
 		return;
 	}
-	this_cpu_write(rcu_data.rcu_urgent_qs, false);
+	__this_cpu_write(rcu_data.rcu_urgent_qs, false);
 	if (unlikely(raw_cpu_read(rcu_data.rcu_need_heavy_qs))) {
 		local_irq_save(flags);
 		rcu_momentary_dyntick_idle();
-- 
2.25.1


  reply	other threads:[~2021-07-05 23:44 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-05 23:43 [PATCH 1/2] rcu: Explain why rcu_all_qs() is a stub in preemptible TREE RCU Frederic Weisbecker
2021-07-05 23:43 ` Frederic Weisbecker [this message]
2021-07-06  7:51   ` [PATCH 2/2] rcu: Remove needless preemption disablement in rcu_all_qs() Peter Zijlstra
2021-07-06 12:30     ` Frederic Weisbecker
2021-07-06 13:28       ` Boqun Feng
2021-07-06 16:24         ` Paul E. McKenney
2021-07-06 16:46 ` [PATCH 1/2] rcu: Explain why rcu_all_qs() is a stub in preemptible TREE RCU Paul E. McKenney

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