[CPUFREQ] kobj refcount fixes.

Wait with the destruction of cpufreq objects until all references
are gone (code partly based on rmk's comparable patch for the PCMCIA
subsystem.

From Dominik.

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index a2fee295ae1a137dc9aa9f0e4619fb281b193333..5a75fc3a69f21c1ec9933e88e90b8e8b73fa95c5 100644 (file)
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -20,6 +20,7 @@
 #include <linux/device.h>
 #include <linux/kobject.h>
 #include <linux/sysfs.h>
+#include <linux/completion.h>
 
 #define CPUFREQ_NAME_LEN 16
 
@@ -71,6 +72,7 @@ struct cpufreq_policy {
        struct kobject          kobj;
        struct semaphore        lock;   /* CPU ->setpolicy or ->target may
                                           only be called once a time */
+       struct completion       kobj_unregister;
 };
 
 #define CPUFREQ_ADJUST          (0)

diff --git a/kernel/cpufreq.c b/kernel/cpufreq.c
index 18245832d8c9644f0a1dca4643f593cab1ea5207..0701eed77ab4a038bfa1c5456bad4120aa115eaf 100644 (file)
--- a/kernel/cpufreq.c
+++ b/kernel/cpufreq.c
@@ -23,6 +23,7 @@
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
+#include <linux/completion.h>
 
 /**
  * The "cpufreq driver" - the arch- or hardware-dependend low
@@ -297,6 +298,12 @@ static ssize_t store(struct kobject * kobj, struct attribute * attr,
        return ret;
 }
 
+static void cpufreq_sysfs_release(struct kobject * kobj)
+{
+       struct cpufreq_policy * policy = to_policy(kobj);
+       complete(&policy->kobj_unregister);
+}
+
 static struct sysfs_ops sysfs_ops = {
        .show   = show,
        .store  = store,
@@ -305,6 +312,7 @@ static struct sysfs_ops sysfs_ops = {
 static struct kobj_type ktype_cpufreq = {
        .sysfs_ops      = &sysfs_ops,
        .default_attrs  = default_attrs,
+       .release        = cpufreq_sysfs_release,
 };
 
 
@@ -343,6 +351,8 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
        up(&cpufreq_driver_sem);
 
        init_MUTEX(&policy->lock);
+       init_completion(&policy->kobj_unregister);
+
        /* prepare interface data */
        policy->kobj.parent = &sys_dev->kobj;
        policy->kobj.ktype = &ktype_cpufreq;
@@ -361,8 +371,10 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
        
        /* set default policy */
        ret = cpufreq_set_policy(&new_policy);
-       if (ret)
+       if (ret) {
                kobject_unregister(&policy->kobj);
+               wait_for_completion(&policy->kobj_unregister);
+       }
 
  out:
        module_put(cpufreq_driver->owner);
@@ -400,6 +412,13 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
 
        up(&cpufreq_driver_sem);
        kobject_put(&cpufreq_driver->policy[cpu].kobj);
+
+       /* we need to make sure that the underlying kobj is actually
+        * destroyed before we proceed e.g. with cpufreq driver module
+        * unloading
+        */
+       wait_for_completion(&cpufreq_driver->policy[cpu].kobj_unregister);
+
        return 0;
 }