Subject: revert cpu/hotplug: Provide cpus_read|write_[un]lock()
From: Mike Galbraith |mgalbraith@suse.de>
Date: Wed Aug 22 07:33:59 CEST 2018
Patch-mainline: Never, -rt specific
References: SLE Realtime Extension

Part of massive/validated RT patch set all-in-one hotplug update.

Signed-off-by: Mike Galbraith |mgalbraith@suse.de>
---
 include/linux/cpu.h |   32 ++++++++++++++------------------
 kernel/cpu.c        |   36 ++++++++++++++++++------------------
 2 files changed, 32 insertions(+), 36 deletions(-)

--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -112,30 +112,26 @@ static inline void cpu_maps_update_done(
 extern struct bus_type cpu_subsys;
 
 #ifdef CONFIG_HOTPLUG_CPU
-extern void cpus_write_lock(void);
-extern void cpus_write_unlock(void);
-extern void cpus_read_lock(void);
-extern void cpus_read_unlock(void);
+/* Stop CPUs going up and down. */
+
+extern void cpu_hotplug_begin(void);
+extern void cpu_hotplug_done(void);
+extern void get_online_cpus(void);
+extern void put_online_cpus(void);
 extern void cpu_hotplug_disable(void);
 extern void cpu_hotplug_enable(void);
 void clear_tasks_mm_cpumask(int cpu);
 int cpu_down(unsigned int cpu);
 
-#else /* CONFIG_HOTPLUG_CPU */
-
-static inline void cpus_write_lock(void) { }
-static inline void cpus_write_unlock(void) { }
-static inline void cpus_read_lock(void) { }
-static inline void cpus_read_unlock(void) { }
-static inline void cpu_hotplug_disable(void) { }
-static inline void cpu_hotplug_enable(void) { }
-#endif	/* !CONFIG_HOTPLUG_CPU */
+#else		/* CONFIG_HOTPLUG_CPU */
 
-/* Wrappers which go away once all code is converted */
-static inline void cpu_hotplug_begin(void) { cpus_write_lock(); }
-static inline void cpu_hotplug_done(void) { cpus_write_unlock(); }
-static inline void get_online_cpus(void) { cpus_read_lock(); }
-static inline void put_online_cpus(void) { cpus_read_unlock(); }
+static inline void cpu_hotplug_begin(void) {}
+static inline void cpu_hotplug_done(void) {}
+#define get_online_cpus()	do { } while (0)
+#define put_online_cpus()	do { } while (0)
+#define cpu_hotplug_disable()	do { } while (0)
+#define cpu_hotplug_enable()	do { } while (0)
+#endif		/* CONFIG_HOTPLUG_CPU */
 
 #ifdef CONFIG_PM_SLEEP_SMP
 extern int freeze_secondary_cpus(int primary);
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -237,7 +237,7 @@ static struct {
 #define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)
 
 
-void cpus_read_lock(void)
+void get_online_cpus(void)
 {
 	might_sleep();
 	if (cpu_hotplug.active_writer == current)
@@ -247,9 +247,9 @@ void cpus_read_lock(void)
 	atomic_inc(&cpu_hotplug.refcount);
 	mutex_unlock(&cpu_hotplug.lock);
 }
-EXPORT_SYMBOL_GPL(cpus_read_lock);
+EXPORT_SYMBOL_GPL(get_online_cpus);
 
-void cpus_read_unlock(void)
+void put_online_cpus(void)
 {
 	int refcount;
 
@@ -266,7 +266,7 @@ void cpus_read_unlock(void)
 	cpuhp_lock_release();
 
 }
-EXPORT_SYMBOL_GPL(cpus_read_unlock);
+EXPORT_SYMBOL_GPL(put_online_cpus);
 
 /*
  * This ensures that the hotplug operation can begin only when the
@@ -290,7 +290,7 @@ EXPORT_SYMBOL_GPL(cpus_read_unlock);
  * get_online_cpus() not an api which is called all that often.
  *
  */
-void cpus_write_lock(void)
+void cpu_hotplug_begin(void)
 {
 	DEFINE_WAIT(wait);
 
@@ -308,7 +308,7 @@ void cpus_write_lock(void)
 	finish_wait(&cpu_hotplug.wq, &wait);
 }
 
-void cpus_write_unlock(void)
+void cpu_hotplug_done(void)
 {
 	cpu_hotplug.active_writer = NULL;
 	mutex_unlock(&cpu_hotplug.lock);
@@ -858,7 +858,7 @@ static int __ref _cpu_down(unsigned int
 	if (!cpu_present(cpu))
 		return -EINVAL;
 
-	cpus_write_lock();
+	cpu_hotplug_begin();
 
 	cpuhp_tasks_frozen = tasks_frozen;
 
@@ -896,7 +896,7 @@ static int __ref _cpu_down(unsigned int
 	}
 
 out:
-	cpus_write_unlock();
+	cpu_hotplug_done();
 	return ret;
 }
 
@@ -967,7 +967,7 @@ static int _cpu_up(unsigned int cpu, int
 	struct task_struct *idle;
 	int ret = 0;
 
-	cpus_write_lock();
+	cpu_hotplug_begin();
 
 	if (!cpu_present(cpu)) {
 		ret = -EINVAL;
@@ -1015,7 +1015,7 @@ static int _cpu_up(unsigned int cpu, int
 	target = min((int)target, CPUHP_BRINGUP_CPU);
 	ret = cpuhp_up_callbacks(cpu, st, target);
 out:
-	cpus_write_unlock();
+	cpu_hotplug_done();
 	arch_smt_update();
 	return ret;
 }
@@ -1513,7 +1513,7 @@ int __cpuhp_state_add_instance(enum cpuh
 	if (sp->multi_instance == false)
 		return -EINVAL;
 
-	cpus_read_lock();
+	get_online_cpus();
 	mutex_lock(&cpuhp_state_mutex);
 
 	if (!invoke || !sp->startup.multi)
@@ -1542,7 +1542,7 @@ add_node:
 	hlist_add_head(node, &sp->list);
 unlock:
 	mutex_unlock(&cpuhp_state_mutex);
-	cpus_read_unlock();
+	put_online_cpus();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
@@ -1575,7 +1575,7 @@ int __cpuhp_setup_state(enum cpuhp_state
 	if (cpuhp_cb_check(state) || !name)
 		return -EINVAL;
 
-	cpus_read_lock();
+	get_online_cpus();
 	mutex_lock(&cpuhp_state_mutex);
 
 	ret = cpuhp_store_callbacks(state, name, startup, teardown,
@@ -1611,7 +1611,7 @@ int __cpuhp_setup_state(enum cpuhp_state
 	}
 out:
 	mutex_unlock(&cpuhp_state_mutex);
-	cpus_read_unlock();
+	put_online_cpus();
 	/*
 	 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
 	 * dynamically allocated state in case of success.
@@ -1633,7 +1633,7 @@ int __cpuhp_state_remove_instance(enum c
 	if (!sp->multi_instance)
 		return -EINVAL;
 
-	cpus_read_lock();
+	get_online_cpus();
 	mutex_lock(&cpuhp_state_mutex);
 
 	if (!invoke || !cpuhp_get_teardown_cb(state))
@@ -1654,7 +1654,7 @@ int __cpuhp_state_remove_instance(enum c
 remove:
 	hlist_del(node);
 	mutex_unlock(&cpuhp_state_mutex);
-	cpus_read_unlock();
+	put_online_cpus();
 
 	return 0;
 }
@@ -1676,7 +1676,7 @@ void __cpuhp_remove_state(enum cpuhp_sta
 
 	BUG_ON(cpuhp_cb_check(state));
 
-	cpus_read_lock();
+	get_online_cpus();
 
 	mutex_lock(&cpuhp_state_mutex);
 	if (sp->multi_instance) {
@@ -1704,7 +1704,7 @@ void __cpuhp_remove_state(enum cpuhp_sta
 remove:
 	cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
 	mutex_unlock(&cpuhp_state_mutex);
-	cpus_read_unlock();
+	put_online_cpus();
 }
 EXPORT_SYMBOL(__cpuhp_remove_state);