From: Waiman Long <longman@redhat.com>
To: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Frederic Weisbecker <frederic@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
"Paul E. McKenney" <paulmck@kernel.org>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
Boqun Feng <boqun.feng@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Shuah Khan <shuah@kernel.org>
Cc: cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
linux-kselftest@vger.kernel.org, Mrunal Patel <mpatel@redhat.com>,
Ryan Phillips <rphillips@redhat.com>,
Brent Rowsell <browsell@redhat.com>,
Peter Hunt <pehunt@redhat.com>,
Cestmir Kalina <ckalina@redhat.com>,
Nicolas Saenz Julienne <nsaenz@kernel.org>,
Alex Gladkov <agladkov@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Phil Auld <pauld@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Daniel Bristot de Oliveira <bristot@kernel.org>,
Juri Lelli <juri.lelli@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Costa Shulyupin <cshulyup@redhat.com>,
Waiman Long <longman@redhat.com>
Subject: [RFC PATCH 2/8] rcu/nocb: Prepare to change nocb cpumask from CPU-hotplug protected cpuset caller
Date: Wed, 17 Jan 2024 11:35:05 -0500 [thread overview]
Message-ID: <20240117163511.88173-3-longman@redhat.com> (raw)
In-Reply-To: <20240117163511.88173-1-longman@redhat.com>
From: Frederic Weisbecker <frederic@kernel.org>
cpusets is going to use the NOCB (de-)offloading interface while
holding hotplug lock. Therefore pull out the responsibility of protecting
against concurrent CPU-hotplug changes to the callers of
rcu_nocb_cpumask_update().
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Phil Auld <pauld@redhat.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
kernel/rcu/rcutorture.c | 2 ++
kernel/rcu/tree_nocb.h | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 228a5488eb5e..e935152346ff 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2139,6 +2139,7 @@ static int rcu_nocb_toggle(void *arg)
do {
r = torture_random(&rand);
cpu = (r >> 1) % (maxcpu + 1);
+ cpus_read_lock();
if (r & 0x1) {
rcu_nocb_cpumask_update(cpumask_of(cpu), true);
atomic_long_inc(&n_nocb_offload);
@@ -2146,6 +2147,7 @@ static int rcu_nocb_toggle(void *arg)
rcu_nocb_cpumask_update(cpumask_of(cpu), false);
atomic_long_inc(&n_nocb_deoffload);
}
+ cpus_read_unlock();
toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval;
set_current_state(TASK_INTERRUPTIBLE);
schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL);
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 60b0a15ed6e2..bbcf6f4152a3 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -1301,12 +1301,13 @@ int rcu_nocb_cpumask_update(const struct cpumask *cpumask, bool offload)
int err_cpu;
cpumask_var_t saved_nocb_mask;
+ lockdep_assert_cpus_held();
+
if (!alloc_cpumask_var(&saved_nocb_mask, GFP_KERNEL))
return -ENOMEM;
cpumask_copy(saved_nocb_mask, rcu_nocb_mask);
- cpus_read_lock();
mutex_lock(&rcu_state.barrier_mutex);
for_each_cpu(cpu, cpumask) {
if (offload) {
@@ -1340,7 +1341,6 @@ int rcu_nocb_cpumask_update(const struct cpumask *cpumask, bool offload)
}
mutex_unlock(&rcu_state.barrier_mutex);
- cpus_read_unlock();
free_cpumask_var(saved_nocb_mask);
--
2.39.3
next prev parent reply other threads:[~2024-01-17 16:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-17 16:35 [RFC PATCH 0/8] cgroup/cpuset: Support RCU_NOCB on isolated partitions Waiman Long
2024-01-17 16:35 ` [RFC PATCH 1/8] rcu/nocb: Pass a cpumask instead of a single CPU to offload/deoffload Waiman Long
2024-01-17 16:35 ` Waiman Long [this message]
2024-01-17 16:35 ` [RFC PATCH 3/8] rcu/no_cb: Add rcu_nocb_enabled() to expose the rcu_nocb state Waiman Long
2024-01-17 16:35 ` [RFC PATCH 4/8] cgroup/cpuset: Better tracking of addition/deletion of isolated CPUs Waiman Long
2024-01-17 16:35 ` [RFC PATCH 5/8] cgroup/cpuset: Add cpuset.cpus.isolation_full Waiman Long
2024-01-17 16:35 ` [RFC PATCH 6/8] cgroup/cpuset: Enable dynamic rcu_nocb mode on isolated CPUs Waiman Long
2024-01-17 16:35 ` [RFC PATCH 7/8] cgroup/cpuset: Document the new cpuset.cpus.isolation_full control file Waiman Long
2024-01-17 16:35 ` [RFC PATCH 8/8] cgroup/cpuset: Update test_cpuset_prs.sh to handle cpuset.cpus.isolation_full Waiman Long
2024-01-17 17:07 ` [RFC PATCH 0/8] cgroup/cpuset: Support RCU_NOCB on isolated partitions Tejun Heo
2024-01-17 17:15 ` Waiman Long
2024-02-06 12:56 ` Frederic Weisbecker
2024-02-06 19:15 ` Marcelo Tosatti
2024-02-07 14:47 ` Frederic Weisbecker
2024-02-07 14:59 ` Marcelo Tosatti
2024-02-10 4:19 ` Waiman Long
2024-01-19 10:24 ` Paul E. McKenney
2024-02-11 1:46 ` Waiman Long
2024-01-22 15:07 ` Michal Koutný
2024-01-23 5:50 ` Waiman Long
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