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Date: Thu, 23 Jul 2015 13:43:19 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Rafael Wysocki <rjw@...ysocki.net>
Cc: linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
linux@....linux.org.uk, Viresh Kumar <viresh.kumar@...aro.org>,
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 2/3] cpufreq: Create links for offline CPUs that got added earlier
If subsys callback ->add_dev() is called for an offline CPU, before its
policy is allocated, we will miss adding its sysfs symlink.
Fix this by tracking such CPUs in a separate mask.
Fixes: 9b07109f06a1 ("cpufreq: Fix double addition of sysfs links")
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
drivers/cpufreq/cpufreq.c | 74 +++++++++++++++++++++++++++++++++++++++--------
1 file changed, 62 insertions(+), 12 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 84504ae3fb38..d01cad993fa7 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -31,6 +31,12 @@
#include <linux/tick.h>
#include <trace/events/power.h>
+/*
+ * CPUs that were offline when a request to allocate policy was issued, symlinks
+ * for them should be created once the policy is available for them.
+ */
+cpumask_t linked_cpus_pending;
+
static LIST_HEAD(cpufreq_policy_list);
static inline bool policy_is_inactive(struct cpufreq_policy *policy)
@@ -938,6 +944,47 @@ void cpufreq_sysfs_remove_file(const struct attribute *attr)
}
EXPORT_SYMBOL(cpufreq_sysfs_remove_file);
+static int cpufreq_add_symlink(struct cpufreq_policy *policy,
+ struct device *dev)
+{
+ int ret, cpu = dev->id;
+
+ dev_dbg(dev, "%s: Adding symlink for CPU: %u\n", __func__, cpu);
+ ret = sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq");
+ if (ret) {
+ dev_err(dev, "%s: Failed to create link (%d)\n", __func__, ret);
+ return ret;
+ }
+
+ /* Track CPUs for which sysfs links are created */
+ cpumask_set_cpu(cpu, policy->linked_cpus);
+ return 0;
+}
+
+/*
+ * Create symlinks for CPUs which are already added via subsys callbacks (and
+ * were offline then), before the policy was created.
+ */
+static int cpufreq_add_pending_symlinks(struct cpufreq_policy *policy)
+{
+ struct cpumask mask;
+ int cpu, ret;
+
+ cpumask_and(&mask, policy->related_cpus, &linked_cpus_pending);
+
+ if (cpumask_empty(&mask))
+ return 0;
+
+ for_each_cpu(cpu, &mask) {
+ ret = cpufreq_add_symlink(policy, get_cpu_device(cpu));
+ if (ret)
+ return ret;
+ cpumask_clear_cpu(cpu, &linked_cpus_pending);
+ }
+
+ return 0;
+}
+
static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
struct device *dev)
{
@@ -968,7 +1015,7 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
return ret;
}
- return 0;
+ return cpufreq_add_pending_symlinks(policy);
}
static int cpufreq_init_policy(struct cpufreq_policy *policy)
@@ -1170,24 +1217,21 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
/* sysfs links are only created on subsys callback */
if (sif && policy) {
- pr_debug("%s: Adding symlink for CPU: %u\n", __func__, cpu);
- ret = sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq");
- if (ret) {
- dev_err(dev, "%s: Failed to create link (%d)\n",
- __func__, ret);
+ ret = cpufreq_add_symlink(policy, dev);
+ if (ret)
return ret;
- }
-
- /* Track CPUs for which sysfs links are created */
- cpumask_set_cpu(cpu, policy->linked_cpus);
}
/*
* A hotplug notifier will follow and we will take care of rest
* of the initialization then.
*/
- if (cpu_is_offline(cpu))
+ if (cpu_is_offline(cpu)) {
+ /* symlink should be added for this CPU later */
+ if (!policy)
+ cpumask_set_cpu(cpu, &linked_cpus_pending);
return 0;
+ }
/* Check if this CPU already has a policy to manage it */
if (policy && !policy_is_inactive(policy)) {
@@ -1440,8 +1484,10 @@ static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
int ret;
- if (!policy)
+ if (!policy) {
+ cpumask_clear_cpu(cpu, &linked_cpus_pending);
return 0;
+ }
if (cpu_online(cpu)) {
ret = __cpufreq_remove_dev_prepare(dev, sif);
@@ -2533,10 +2579,14 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
/* Protect against concurrent cpu hotplug */
get_online_cpus();
+
subsys_interface_unregister(&cpufreq_interface);
if (cpufreq_boost_supported())
cpufreq_sysfs_remove_file(&boost.attr);
+ if (WARN_ON(!cpumask_empty(&linked_cpus_pending)))
+ cpumask_clear(&linked_cpus_pending);
+
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
write_lock_irqsave(&cpufreq_driver_lock, flags);
--
2.4.0
--
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