cpu/hotplug: Provide cpus_read|write_[un]lock()

The counting 'rwsem' hackery of get|put_online_cpus() is going to be
replaced by percpu rwsem.

Rename the functions to make it clear that it's locking and not some
refcount style interface. These new functions will be used for the
preparatory patches which make the code ready for the percpu rwsem
conversion.

Rename all instances in the cpu hotplug code while at it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.080397752@linutronix.de

1 files changed, 18 insertions, 18 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 9ae6fbe5b5cf..d3221ae5b474 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -235,7 +235,7 @@ static struct {
 #define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)
 
 
-void get_online_cpus(void)
+void cpus_read_lock(void)
 {
 	might_sleep();
 	if (cpu_hotplug.active_writer == current)
@@ -245,9 +245,9 @@ void get_online_cpus(void)
 	atomic_inc(&cpu_hotplug.refcount);
 	mutex_unlock(&cpu_hotplug.lock);
 }
-EXPORT_SYMBOL_GPL(get_online_cpus);
+EXPORT_SYMBOL_GPL(cpus_read_lock);
 
-void put_online_cpus(void)
+void cpus_read_unlock(void)
 {
 	int refcount;
 
@@ -264,7 +264,7 @@ void put_online_cpus(void)
 	cpuhp_lock_release();
 
 }
-EXPORT_SYMBOL_GPL(put_online_cpus);
+EXPORT_SYMBOL_GPL(cpus_read_unlock);
 
 /*
  * This ensures that the hotplug operation can begin only when the
@@ -288,7 +288,7 @@ EXPORT_SYMBOL_GPL(put_online_cpus);
  * get_online_cpus() not an api which is called all that often.
  *
  */
-void cpu_hotplug_begin(void)
+void cpus_write_lock(void)
 {
 	DEFINE_WAIT(wait);
 
@@ -306,7 +306,7 @@ void cpu_hotplug_begin(void)
 	finish_wait(&cpu_hotplug.wq, &wait);
 }
 
-void cpu_hotplug_done(void)
+void cpus_write_unlock(void)
 {
 	cpu_hotplug.active_writer = NULL;
 	mutex_unlock(&cpu_hotplug.lock);
@@ -773,7 +773,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
 	if (!cpu_present(cpu))
 		return -EINVAL;
 
-	cpu_hotplug_begin();
+	cpus_write_lock();
 
 	cpuhp_tasks_frozen = tasks_frozen;
 
@@ -811,7 +811,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
 	}
 
 out:
-	cpu_hotplug_done();
+	cpus_write_unlock();
 	return ret;
 }
 
@@ -893,7 +893,7 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 	struct task_struct *idle;
 	int ret = 0;
 
-	cpu_hotplug_begin();
+	cpus_write_lock();
 
 	if (!cpu_present(cpu)) {
 		ret = -EINVAL;
@@ -941,7 +941,7 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 	target = min((int)target, CPUHP_BRINGUP_CPU);
 	ret = cpuhp_up_callbacks(cpu, st, target);
 out:
-	cpu_hotplug_done();
+	cpus_write_unlock();
 	return ret;
 }
 
@@ -1424,7 +1424,7 @@ int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
 	if (sp->multi_instance == false)
 		return -EINVAL;
 
-	get_online_cpus();
+	cpus_read_lock();
 	mutex_lock(&cpuhp_state_mutex);
 
 	if (!invoke || !sp->startup.multi)
@@ -1453,7 +1453,7 @@ add_node:
 	hlist_add_head(node, &sp->list);
 unlock:
 	mutex_unlock(&cpuhp_state_mutex);
-	put_online_cpus();
+	cpus_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
@@ -1486,7 +1486,7 @@ int __cpuhp_setup_state(enum cpuhp_state state,
 	if (cpuhp_cb_check(state) || !name)
 		return -EINVAL;
 
-	get_online_cpus();
+	cpus_read_lock();
 	mutex_lock(&cpuhp_state_mutex);
 
 	ret = cpuhp_store_callbacks(state, name, startup, teardown,
@@ -1522,7 +1522,7 @@ int __cpuhp_setup_state(enum cpuhp_state state,
 	}
 out:
 	mutex_unlock(&cpuhp_state_mutex);
-	put_online_cpus();
+	cpus_read_unlock();
 	/*
 	 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
 	 * dynamically allocated state in case of success.
@@ -1544,7 +1544,7 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state,
 	if (!sp->multi_instance)
 		return -EINVAL;
 
-	get_online_cpus();
+	cpus_read_lock();
 	mutex_lock(&cpuhp_state_mutex);
 
 	if (!invoke || !cpuhp_get_teardown_cb(state))
@@ -1565,7 +1565,7 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state,
 remove:
 	hlist_del(node);
 	mutex_unlock(&cpuhp_state_mutex);
-	put_online_cpus();
+	cpus_read_unlock();
 
 	return 0;
 }
@@ -1587,7 +1587,7 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
 
 	BUG_ON(cpuhp_cb_check(state));
 
-	get_online_cpus();
+	cpus_read_lock();
 
 	mutex_lock(&cpuhp_state_mutex);
 	if (sp->multi_instance) {
@@ -1615,7 +1615,7 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
 remove:
 	cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
 	mutex_unlock(&cpuhp_state_mutex);
-	put_online_cpus();
+	cpus_read_unlock();
 }
 EXPORT_SYMBOL(__cpuhp_remove_state);