cpufreq: Ref the policy object sooner

Do it before it's assigned to cpufreq_cpu_data, otherwise when a driver
tries to get the cpu frequency during initialization the policy kobj is
referenced and we get this warning:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 64 at include/linux/kref.h:47 kobject_get+0x64/0x70()
Modules linked in:
CPU: 1 PID: 64 Comm: irq/77-tegra-ac Not tainted 3.18.0-rc4-next-20141114ccu-00050-g3eff942 #326
[<c0016fac>] (unwind_backtrace) from [<c001272c>] (show_stack+0x10/0x14)
[<c001272c>] (show_stack) from [<c06085d8>] (dump_stack+0x98/0xd8)
[<c06085d8>] (dump_stack) from [<c002892c>] (warn_slowpath_common+0x84/0xb4)
[<c002892c>] (warn_slowpath_common) from [<c00289f8>] (warn_slowpath_null+0x1c/0x24)
[<c00289f8>] (warn_slowpath_null) from [<c0220290>] (kobject_get+0x64/0x70)
[<c0220290>] (kobject_get) from [<c03e944c>] (cpufreq_cpu_get+0x88/0xc8)
[<c03e944c>] (cpufreq_cpu_get) from [<c03e9500>] (cpufreq_get+0xc/0x64)
[<c03e9500>] (cpufreq_get) from [<c0285288>] (actmon_thread_isr+0x134/0x198)
[<c0285288>] (actmon_thread_isr) from [<c0069008>] (irq_thread_fn+0x1c/0x40)
[<c0069008>] (irq_thread_fn) from [<c0069324>] (irq_thread+0x134/0x174)
[<c0069324>] (irq_thread) from [<c0040290>] (kthread+0xdc/0xf4)
[<c0040290>] (kthread) from [<c000f4b8>] (ret_from_fork+0x14/0x3c)
---[ end trace b7bd64a81b340c59 ]---

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index c9701e9..de2c3e1 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -900,46 +900,31 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
        struct freq_attr **drv_attr;
        int ret = 0;
 
-       /* prepare interface data */
-       ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
-                                  &dev->kobj, "cpufreq");
-       if (ret)
-               return ret;
-
        /* set up files for this cpu device */
        drv_attr = cpufreq_driver->attr;
        while ((drv_attr) && (*drv_attr)) {
                ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
                if (ret)
-                       goto err_out_kobj_put;
+                       return ret;
                drv_attr++;
        }
        if (cpufreq_driver->get) {
                ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
                if (ret)
-                       goto err_out_kobj_put;
+                       return ret;
        }
 
        ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
        if (ret)
-               goto err_out_kobj_put;
+               return ret;
 
        if (cpufreq_driver->bios_limit) {
                ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
                if (ret)
-                       goto err_out_kobj_put;
+                       return ret;
        }
 
-       ret = cpufreq_add_dev_symlink(policy);
-       if (ret)
-               goto err_out_kobj_put;
-
-       return ret;
-
-err_out_kobj_put:
-       kobject_put(&policy->kobj);
-       wait_for_completion(&policy->kobj_unregister);
-       return ret;
+       return cpufreq_add_dev_symlink(policy);
 }
 
 static void cpufreq_init_policy(struct cpufreq_policy *policy)
@@ -1198,6 +1183,8 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
                goto err_set_policy_cpu;
        }
 
+       down_write(&policy->rwsem);
+
        /* related cpus should atleast have policy->cpus */
        cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
 
@@ -1210,9 +1197,17 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
        if (!recover_policy) {
                policy->user_policy.min = policy->min;
                policy->user_policy.max = policy->max;
+
+               /* prepare interface data */
+               ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
+                                          &dev->kobj, "cpufreq");
+               if (ret) {
+                       pr_err("%s: failed to init policy->kobj: %d\n",
+                              __func__, ret);
+                       goto err_init_policy_kobj;
+               }
        }
 
-       down_write(&policy->rwsem);
        write_lock_irqsave(&cpufreq_driver_lock, flags);
        for_each_cpu(j, policy->cpus)
                per_cpu(cpufreq_cpu_data, j) = policy;
@@ -1303,6 +1298,11 @@ err_get_freq:
                per_cpu(cpufreq_cpu_data, j) = NULL;
        write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
+       if (!recover_policy) {
+               kobject_put(&policy->kobj);
+               wait_for_completion(&policy->kobj_unregister);
+       }
+err_init_policy_kobj:
        up_write(&policy->rwsem);
 
        if (cpufreq_driver->exit)