From: Lai Jiangshan <laijs@linux.alibaba.com>
To: linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
rcu@vger.kernel.org
Subject: [PATCH V2 6/7] rcu: clear the special.b.need_qs in rcu_note_context_switch()
Date: Sat, 2 Nov 2019 12:45:58 +0000 [thread overview]
Message-ID: <20191102124559.1135-7-laijs@linux.alibaba.com> (raw)
In-Reply-To: <20191102124559.1135-1-laijs@linux.alibaba.com>
It is better to clear the special.b.need_qs when it is
replaced by special.b.blocked or it is really fulfill its
goal in rcu_preempt_deferred_qs_irqrestore().
It makes rcu_qs() easier to be understood, and also prepares for
the percpu rcu_preempt_depth patch, which reqires rcu_special
bits to be clearred in irq-disable context.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
kernel/rcu/tree_plugin.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index eb5906c55c8d..e16c3867d2ff 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -264,8 +264,6 @@ static void rcu_qs(void)
__this_cpu_read(rcu_data.gp_seq),
TPS("cpuqs"));
__this_cpu_write(rcu_data.cpu_no_qs.b.norm, false);
- barrier(); /* Coordinate with rcu_flavor_sched_clock_irq(). */
- WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, false);
}
}
@@ -297,6 +295,7 @@ void rcu_note_context_switch(bool preempt)
/* Possibly blocking in an RCU read-side critical section. */
rnp = rdp->mynode;
raw_spin_lock_rcu_node(rnp);
+ t->rcu_read_unlock_special.b.need_qs = false;
t->rcu_read_unlock_special.b.blocked = true;
t->rcu_blocked_node = rnp;
--
2.20.1
next prev parent reply other threads:[~2019-11-02 12:47 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-02 12:45 [PATCH V2 0/7] rcu: introduce percpu rcu_preempt_depth Lai Jiangshan
2019-11-02 12:45 ` [PATCH V2 1/7] rcu: use preempt_count to test whether scheduler locks is held Lai Jiangshan
2019-11-15 16:53 ` Paul E. McKenney
2020-02-19 3:31 ` Joel Fernandes
2020-02-19 3:59 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 2/7] rcu: cleanup rcu_preempt_deferred_qs() Lai Jiangshan
2019-11-03 2:01 ` Boqun Feng
2019-11-03 5:01 ` Lai Jiangshan
2019-11-04 14:55 ` Paul E. McKenney
2019-11-05 2:09 ` Lai Jiangshan
2019-11-05 7:19 ` Paul E. McKenney
2019-11-11 14:32 ` Paul E. McKenney
2019-11-12 1:28 ` Lai Jiangshan
2020-02-17 23:23 ` Paul E. McKenney
2020-02-18 14:41 ` Steven Rostedt
2020-02-18 16:43 ` Paul E. McKenney
2019-11-15 16:55 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 3/7] rcu: remove useless special.b.deferred_qs Lai Jiangshan
2020-02-17 23:23 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 4/7] rcu: don't use negative ->rcu_read_lock_nesting Lai Jiangshan
2020-02-17 23:26 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 5/7] rcu: wrap usages of rcu_read_lock_nesting Lai Jiangshan
2019-11-15 22:25 ` Paul E. McKenney
2019-11-02 12:45 ` Lai Jiangshan [this message]
2019-11-16 15:46 ` [PATCH V2 6/7] rcu: clear the special.b.need_qs in rcu_note_context_switch() Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 7/7] x86,rcu: use percpu rcu_preempt_depth Lai Jiangshan
2019-11-02 16:30 ` Borislav Petkov
2019-11-03 4:33 ` Lai Jiangshan
2019-11-04 9:25 ` Sebastian Andrzej Siewior
2019-11-04 11:41 ` Lai Jiangshan
2019-11-04 12:09 ` Sebastian Andrzej Siewior
2019-11-16 15:48 ` Paul E. McKenney
2019-11-18 2:02 ` Lai Jiangshan
2019-11-18 14:59 ` Paul E. McKenney
2019-11-19 1:59 ` Lai Jiangshan
2019-11-19 21:14 ` Paul E. McKenney
2019-11-20 2:47 ` Lai Jiangshan
2019-11-21 4:02 ` Paul E. McKenney
2019-11-02 15:05 ` [PATCH V2 0/7] rcu: introduce " Paul E. McKenney
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