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 01/10] rcu: Directly lock rdp->nocb_lock on nocb code entrypoints
Date: Wed, 13 May 2020 18:47:05 +0200 [thread overview]
Message-ID: <20200513164714.22557-2-frederic@kernel.org> (raw)
In-Reply-To: <20200513164714.22557-1-frederic@kernel.org>
Pure NOCB code entrypoints (nocb_cb kthread, nocb_gp kthread, nocb
timers) can unconditionally lock rdp->nocb_lock as they always execute
in the context of an offloaded rdp.
This also prepare for toggling CPUs to/from callback's offloaded mode
where the offloaded state will possibly change when rdp->nocb_lock
isn't taken. We'll still want the entrypoints to lock the rdp in any
case.
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 | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 097635c41135..523570469864 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1909,7 +1909,7 @@ static void do_nocb_bypass_wakeup_timer(struct timer_list *t)
struct rcu_data *rdp = from_timer(rdp, t, nocb_bypass_timer);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Timer"));
- rcu_nocb_lock_irqsave(rdp, flags);
+ raw_spin_lock_irqsave(&rdp->nocb_lock, flags);
smp_mb__after_spinlock(); /* Timer expire before wakeup. */
__call_rcu_nocb_wake(rdp, true, flags);
}
@@ -1942,7 +1942,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
*/
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
- rcu_nocb_lock_irqsave(rdp, flags);
+ raw_spin_lock_irqsave(&rdp->nocb_lock, flags);
bypass_ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
if (bypass_ncbs &&
(time_after(j, READ_ONCE(rdp->nocb_bypass_first) + 1) ||
@@ -1951,7 +1951,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
(void)rcu_nocb_try_flush_bypass(rdp, j);
bypass_ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
} else if (!bypass_ncbs && rcu_segcblist_empty(&rdp->cblist)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
continue; /* No callbacks here, try next. */
}
if (bypass_ncbs) {
@@ -1996,7 +1996,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
} else {
needwake = false;
}
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
if (needwake) {
swake_up_one(&rdp->nocb_cb_wq);
gotcbs = true;
@@ -2084,7 +2084,7 @@ static void nocb_cb_wait(struct rcu_data *rdp)
rcu_do_batch(rdp);
local_bh_enable();
lockdep_assert_irqs_enabled();
- rcu_nocb_lock_irqsave(rdp, flags);
+ raw_spin_lock_irqsave(&rdp->nocb_lock, flags);
if (rcu_segcblist_nextgp(&rdp->cblist, &cur_gp_seq) &&
rcu_seq_done(&rnp->gp_seq, cur_gp_seq) &&
raw_spin_trylock_rcu_node(rnp)) { /* irqs already disabled. */
@@ -2092,7 +2092,7 @@ static void nocb_cb_wait(struct rcu_data *rdp)
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
}
if (rcu_segcblist_ready_cbs(&rdp->cblist)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
if (needwake_gp)
rcu_gp_kthread_wake();
return;
@@ -2100,7 +2100,7 @@ static void nocb_cb_wait(struct rcu_data *rdp)
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("CBSleep"));
WRITE_ONCE(rdp->nocb_cb_sleep, true);
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
if (needwake_gp)
rcu_gp_kthread_wake();
swait_event_interruptible_exclusive(rdp->nocb_cb_wq,
--
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 ` Frederic Weisbecker [this message]
2020-05-20 12:29 ` [PATCH 01/10] rcu: Directly lock rdp->nocb_lock on nocb code entrypoints 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 ` [PATCH 02/10] rcu: Use direct rdp->nocb_lock operations on local calls Frederic Weisbecker
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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