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>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>
Subject: [PATCH 02/10] rcu: Use direct rdp->nocb_lock operations on local calls
Date: Wed, 13 May 2020 18:47:06 +0200 [thread overview]
Message-ID: <20200513164714.22557-3-frederic@kernel.org> (raw)
In-Reply-To: <20200513164714.22557-1-frederic@kernel.org>
Unconditionally lock rdp->nocb_lock on nocb code that is called after
we verified that the rdp is offloaded:
This clarify the locking rules and expectations.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
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>
---
kernel/rcu/tree_plugin.h | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 523570469864..1d22b16c03e0 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1628,11 +1628,11 @@ static void wake_nocb_gp(struct rcu_data *rdp, bool force,
if (!READ_ONCE(rdp_gp->nocb_gp_kthread)) {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("AlreadyAwake"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
return;
}
del_timer(&rdp->nocb_timer);
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
if (force || READ_ONCE(rdp_gp->nocb_gp_sleep)) {
WRITE_ONCE(rdp_gp->nocb_gp_sleep, false);
@@ -1753,7 +1753,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
// Don't use ->nocb_bypass during early boot.
if (rcu_scheduler_active != RCU_SCHEDULER_RUNNING) {
- rcu_nocb_lock(rdp);
+ raw_spin_lock(&rdp->nocb_lock);
WARN_ON_ONCE(rcu_cblist_n_cbs(&rdp->nocb_bypass));
*was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
return false;
@@ -1778,7 +1778,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
// this jiffy, tell the caller to enqueue onto ->cblist. But flush
// ->nocb_bypass first.
if (rdp->nocb_nobypass_count < nocb_nobypass_lim_per_jiffy) {
- rcu_nocb_lock(rdp);
+ raw_spin_lock(&rdp->nocb_lock);
*was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
if (*was_alldone)
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
@@ -1792,7 +1792,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
// flush ->nocb_bypass to ->cblist.
if ((ncbs && j != READ_ONCE(rdp->nocb_bypass_first)) ||
ncbs >= qhimark) {
- rcu_nocb_lock(rdp);
+ raw_spin_lock(&rdp->nocb_lock);
if (!rcu_nocb_flush_bypass(rdp, rhp, j)) {
*was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
if (*was_alldone)
@@ -1807,7 +1807,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
rcu_advance_cbs_nowake(rdp->mynode, rdp);
rdp->nocb_gp_adv_time = j;
}
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
return true; // Callback already enqueued.
}
@@ -1827,7 +1827,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
local_irq_restore(flags);
} else {
// No-CBs GP kthread might be indefinitely asleep, if so, wake.
- rcu_nocb_lock(rdp); // Rare during call_rcu() flood.
+ raw_spin_lock(&rdp->nocb_lock); // Rare during call_rcu() flood.
if (!rcu_segcblist_pend_cbs(&rdp->cblist)) {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("FirstBQwake"));
@@ -1835,7 +1835,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
} else {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("FirstBQnoWake"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
}
}
return true; // Callback already enqueued.
@@ -1861,7 +1861,7 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
if (rcu_nocb_poll || !t) {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("WakeNotPoll"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
return;
}
// Need to actually to a wakeup.
@@ -1876,7 +1876,7 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
} else {
wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE,
TPS("WakeEmptyIsDeferred"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
}
} else if (len > rdp->qlen_last_fqs_check + qhimark) {
/* ... or if many callbacks queued. */
@@ -1894,10 +1894,10 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
!timer_pending(&rdp->nocb_bypass_timer))
wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE_FORCE,
TPS("WakeOvfIsDeferred"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
} else {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
}
return;
}
--
2.25.0
next prev parent reply other threads:[~2020-05-13 16:47 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 16:47 [PATCH 00/10] rcu: Allow a CPU to leave and reenter NOCB state Frederic Weisbecker
2020-05-13 16:47 ` [PATCH 01/10] rcu: Directly lock rdp->nocb_lock on nocb code entrypoints Frederic Weisbecker
2020-05-20 12:29 ` Joel Fernandes
2020-05-22 17:57 ` Paul E. McKenney
2020-05-26 15:21 ` Joel Fernandes
2020-05-26 16:29 ` Paul E. McKenney
2020-05-26 20:18 ` Joel Fernandes
2020-05-26 21:09 ` Paul E. McKenney
2020-05-26 21:27 ` Joel Fernandes
2020-05-26 22:29 ` Paul E. McKenney
2020-05-27 0:45 ` Joel Fernandes
2020-05-27 0:58 ` Paul E. McKenney
2020-06-04 11:41 ` Frederic Weisbecker
2020-06-04 16:36 ` Paul E. McKenney
2020-06-08 12:57 ` Frederic Weisbecker
2020-06-09 18:02 ` Paul E. McKenney
2020-06-10 13:12 ` Frederic Weisbecker
2020-06-10 14:02 ` Paul E. McKenney
2020-06-10 22:12 ` Frederic Weisbecker
2020-06-10 23:21 ` Paul E. McKenney
2020-06-11 1:32 ` Joel Fernandes
2020-05-13 16:47 ` Frederic Weisbecker [this message]
2020-05-13 16:47 ` [PATCH 03/10] rcu: Make locking explicit in do_nocb_deferred_wakeup_common() Frederic Weisbecker
2020-05-26 19:54 ` Joel Fernandes
2020-05-26 19:59 ` Joel Fernandes
2020-05-13 16:47 ` [PATCH 04/10] rcu: Implement rcu_segcblist_is_offloaded() config dependent Frederic Weisbecker
2020-05-13 18:20 ` Paul E. McKenney
2020-05-13 23:03 ` Frederic Weisbecker
2020-05-14 15:47 ` Paul E. McKenney
2020-05-13 16:47 ` [PATCH 05/10] rcu: Remove useless conditional nocb unlock Frederic Weisbecker
2020-05-13 16:47 ` [PATCH 06/10] rcu: Make nocb_cb kthread parkable Frederic Weisbecker
2020-06-11 1:34 ` Joel Fernandes
2020-05-13 16:47 ` [PATCH 07/10] rcu: Temporarily assume that nohz full CPUs might not be NOCB Frederic Weisbecker
2020-05-13 18:25 ` Paul E. McKenney
2020-05-13 23:08 ` Frederic Weisbecker
2020-05-14 15:50 ` Paul E. McKenney
2020-05-14 22:49 ` Frederic Weisbecker
2020-05-13 16:47 ` [PATCH 08/10] rcu: Allow to deactivate nocb on a CPU Frederic Weisbecker
2020-05-13 18:38 ` Paul E. McKenney
2020-05-13 22:45 ` Frederic Weisbecker
2020-05-14 15:47 ` Paul E. McKenney
2020-05-14 22:30 ` Frederic Weisbecker
2020-05-14 22:47 ` Paul E. McKenney
2020-05-14 22:55 ` Frederic Weisbecker
2020-05-26 21:20 ` Joel Fernandes
2020-05-26 22:49 ` Joel Fernandes
2020-06-04 13:10 ` Frederic Weisbecker
2020-06-11 1:32 ` Joel Fernandes
2020-06-11 17:03 ` Paul E. McKenney
2020-06-04 13:14 ` Frederic Weisbecker
2020-05-13 16:47 ` [PATCH 09/10] rcu: Allow to re-offload a CPU that used to be nocb Frederic Weisbecker
2020-05-13 18:41 ` Paul E. McKenney
2020-05-13 16:47 ` [PATCH 10/10] rcu: Nocb (de)activate through sysfs Frederic Weisbecker
2020-05-13 18:42 ` Paul E. McKenney
2020-05-13 23:23 ` Frederic Weisbecker
2020-05-14 15:51 ` Paul E. McKenney
2020-05-13 18:15 ` [PATCH 00/10] rcu: Allow a CPU to leave and reenter NOCB state Paul E. McKenney
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