From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Viresh Kumar <viresh.kumar@linaro.org>,
Sudeep Holla <sudeep.holla@arm.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>
Cc: Liviu Dudau <liviu.dudau@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Lukasz Luba <lukasz.luba@arm.com>,
linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] cpufreq: vexpress-spc: Fix wrong alternation of policy->related_cpus during CPU hp
Date: Wed, 27 Nov 2019 12:48:01 +0100 [thread overview]
Message-ID: <20191127114801.23837-1-dietmar.eggemann@arm.com> (raw)
Since commit ca74b316df96 ("arm: Use common cpu_topology structure and
functions.") the core cpumask has to be modified during cpu hotplug
operations.
("arm: Fix topology setup in case of CPU hotplug for CONFIG_SCHED_MC")
[1] fixed that but revealed another issue on TC2, i.e in its cpufreq
driver.
During CPU hp stress operations on multiple CPUs, policy->related_cpus
can be altered. This is wrong since this cpumask should contain the
online and offline CPUs.
The WARN_ON(!cpumask_test_cpu(cpu, policy->related_cpus)) in
cpufreq_online() triggers in this case.
The core cpumask can't be used to set the policy->cpus in
ve_spc_cpufreq_init() anymore in case it is called via
cpuhp_cpufreq_online()->cpufreq_online()->cpufreq_driver->init().
An empty online() callback can be used to avoid that the init()
driver function is called during CPU hotplug in so that
policy->related_cpus will not be changed.
Implementing an online() also requires an offline() callback.
Tested on TC2 with CPU hp stress test (CPU hp from multiple CPUs at
the same time).
[1]
https://lore.kernel.org/r/20191127103353.12417-1-dietmar.eggemann@arm.com
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
drivers/cpufreq/vexpress-spc-cpufreq.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/cpufreq/vexpress-spc-cpufreq.c b/drivers/cpufreq/vexpress-spc-cpufreq.c
index 506e3f2bf53a..857dcb535e97 100644
--- a/drivers/cpufreq/vexpress-spc-cpufreq.c
+++ b/drivers/cpufreq/vexpress-spc-cpufreq.c
@@ -492,6 +492,16 @@ static void ve_spc_cpufreq_ready(struct cpufreq_policy *policy)
cdev[cur_cluster] = of_cpufreq_cooling_register(policy);
}
+static int ve_spc_cpufreq_online(struct cpufreq_policy *policy)
+{
+ return 0;
+}
+
+static int ve_spc_cpufreq_offline(struct cpufreq_policy *policy)
+{
+ return 0;
+}
+
static struct cpufreq_driver ve_spc_cpufreq_driver = {
.name = "vexpress-spc",
.flags = CPUFREQ_STICKY |
@@ -503,6 +513,8 @@ static struct cpufreq_driver ve_spc_cpufreq_driver = {
.init = ve_spc_cpufreq_init,
.exit = ve_spc_cpufreq_exit,
.ready = ve_spc_cpufreq_ready,
+ .online = ve_spc_cpufreq_online,
+ .offline = ve_spc_cpufreq_offline,
.attr = cpufreq_generic_attr,
};
--
2.17.1
next reply other threads:[~2019-11-27 11:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 11:48 Dietmar Eggemann [this message]
2019-11-27 12:07 ` [PATCH] cpufreq: vexpress-spc: Fix wrong alternation of policy->related_cpus during CPU hp Viresh Kumar
2019-11-27 12:10 ` Sudeep Holla
2019-11-27 12:08 ` Sudeep Holla
2019-11-27 12:14 ` Viresh Kumar
2019-11-27 13:32 ` Sudeep Holla
2019-11-27 14:58 ` Dietmar Eggemann
2019-11-27 15:40 ` Sudeep Holla
2019-11-27 18:45 ` Sudeep Holla
2019-11-28 2:31 ` Viresh Kumar
2019-11-28 10:01 ` Dietmar Eggemann
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