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@linaro.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);