[Patch 1/2] cpufreq: unexport (un)lock_policy_rwsem* functions

[Patch 1/2] cpufreq: unexport (un)lock_policy_rwsem* functions

[Amerigo Wang]

lock_policy_rwsem_* and unlock_policy_rwsem_* functions are scheduled
to be unexported when 2.6.33. Now there are no other callers of them
out of cpufreq.c, unexport them and make them static.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Dave Jones <davej@redhat.com>

---
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 73ef30d..13b338f 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -381,16 +381,6 @@ Who:	Eric Paris <eparis@redhat.com>
 
 ----------------------------
 
-What:	lock_policy_rwsem_* and unlock_policy_rwsem_* will not be
-	exported interface anymore.
-When:	2.6.33
-Why:	cpu_policy_rwsem has a new cleaner definition making it local to
-	cpufreq core and contained inside cpufreq.c. Other dependent
-	drivers should not use it in order to safely avoid lockdep issues.
-Who:	Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
-
-----------------------------
-
 What:	sound-slot/service-* module aliases and related clutters in
 	sound/sound_core.c
 When:	August 2010
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 67bc2ec..4de1e5f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -68,7 +68,7 @@ static DEFINE_PER_CPU(int, cpufreq_policy_cpu);
 static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem);
 
 #define lock_policy_rwsem(mode, cpu)					\
-int lock_policy_rwsem_##mode						\
+static int lock_policy_rwsem_##mode					\
 (int cpu)								\
 {									\
 	int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);		\
@@ -83,26 +83,22 @@ int lock_policy_rwsem_##mode						\
 }
 
 lock_policy_rwsem(read, cpu);
-EXPORT_SYMBOL_GPL(lock_policy_rwsem_read);
 
 lock_policy_rwsem(write, cpu);
-EXPORT_SYMBOL_GPL(lock_policy_rwsem_write);
 
-void unlock_policy_rwsem_read(int cpu)
+static void unlock_policy_rwsem_read(int cpu)
 {
 	int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
 	BUG_ON(policy_cpu == -1);
 	up_read(&per_cpu(cpu_policy_rwsem, policy_cpu));
 }
-EXPORT_SYMBOL_GPL(unlock_policy_rwsem_read);
 
-void unlock_policy_rwsem_write(int cpu)
+static void unlock_policy_rwsem_write(int cpu)
 {
 	int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
 	BUG_ON(policy_cpu == -1);
 	up_write(&per_cpu(cpu_policy_rwsem, policy_cpu));
 }
-EXPORT_SYMBOL_GPL(unlock_policy_rwsem_write);
 
 
 /* internal prototypes */
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 4de02b1..7a4a5ff 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -196,11 +196,6 @@ extern int __cpufreq_driver_getavg(struct cpufreq_policy *policy,
 int cpufreq_register_governor(struct cpufreq_governor *governor);
 void cpufreq_unregister_governor(struct cpufreq_governor *governor);
 
-int lock_policy_rwsem_read(int cpu);
-int lock_policy_rwsem_write(int cpu);
-void unlock_policy_rwsem_read(int cpu);
-void unlock_policy_rwsem_write(int cpu);
-
 
 /*********************************************************************
  *                      CPUFREQ DRIVER INTERFACE                     *

[Patch 2/2] cpufreq: fix a lockdep warning

[Amerigo Wang]

There is no need to do sysfs_remove_link() or kobject_put() etc.
when policy_rwsem_write is held, move them after releasing the lock.

This fixes the lockdep warning:

halt/4071 is trying to acquire lock:
 (s_active){++++.+}, at: [<c0000000001ef868>] .sysfs_addrm_finish+0x58/0xc0

but task is already holding lock:
 (&per_cpu(cpu_policy_rwsem, cpu)){+.+.+.}, at: [<c0000000004cd6ac>] .lock_policy_rwsem_write+0x84/0xf4

Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Dave Jones <davej@redhat.com>

---
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 67bc2ec..e196084 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1113,6 +1113,8 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
 	unsigned int cpu = sys_dev->id;
 	unsigned long flags;
 	struct cpufreq_policy *data;
+	struct kobject *kobj;
+	struct completion *cmp;
 #ifdef CONFIG_SMP
 	struct sys_device *cpu_sys_dev;
 	unsigned int j;
@@ -1141,10 +1143,11 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
 		dprintk("removing link\n");
 		cpumask_clear_cpu(cpu, data->cpus);
 		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
-		sysfs_remove_link(&sys_dev->kobj, "cpufreq");
+		kobj = &sys_dev->kobj;
 		cpufreq_cpu_put(data);
 		cpufreq_debug_enable_ratelimit();
 		unlock_policy_rwsem_write(cpu);
+		sysfs_remove_link(kobj, "cpufreq");
 		return 0;
 	}
 #endif
@@ -1181,7 +1184,10 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
 				data->governor->name, CPUFREQ_NAME_LEN);
 #endif
 			cpu_sys_dev = get_cpu_sysdev(j);
-			sysfs_remove_link(&cpu_sys_dev->kobj, "cpufreq");
+			kobj = &cpu_sys_dev->kobj;
+			unlock_policy_rwsem_write(cpu);
+			sysfs_remove_link(kobj, "cpufreq");
+			lock_policy_rwsem_write(cpu);
 			cpufreq_cpu_put(data);
 		}
 	}
@@ -1192,19 +1198,22 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
 	if (cpufreq_driver->target)
 		__cpufreq_governor(data, CPUFREQ_GOV_STOP);
 
-	kobject_put(&data->kobj);
+	kobj = &data->kobj;
+	cmp = &data->kobj_unregister;
+	unlock_policy_rwsem_write(cpu);
+	kobject_put(kobj);
 
 	/* we need to make sure that the underlying kobj is actually
 	 * not referenced anymore by anybody before we proceed with
 	 * unloading.
 	 */
 	dprintk("waiting for dropping of refcount\n");
-	wait_for_completion(&data->kobj_unregister);
+	wait_for_completion(cmp);
 	dprintk("wait complete\n");
 
+	lock_policy_rwsem_write(cpu);
 	if (cpufreq_driver->exit)
 		cpufreq_driver->exit(data);
-
 	unlock_policy_rwsem_write(cpu);
 
 	free_cpumask_var(data->related_cpus);