patches/0004-cpu-hotplug-Add-__cpuhp_state_add_instance_cpuslocke.patch

From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:15 +0200
Subject: [PATCH 04/32] cpu/hotplug: Add
 __cpuhp_state_add_instance_cpuslocked()

Add cpuslocked() variants for the multi instance registration so this can
be called from a cpus_read_lock() protected region.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-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/20170524081547.321782217@linutronix.de
---
 include/linux/cpuhotplug.h |    9 +++++++++
 kernel/cpu.c               |   18 +++++++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -238,6 +238,8 @@ static inline int cpuhp_setup_state_mult
 
 int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
 			       bool invoke);
+int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
+					  struct hlist_node *node, bool invoke);
 
 /**
  * cpuhp_state_add_instance - Add an instance for a state and invoke startup
@@ -270,6 +272,13 @@ static inline int cpuhp_state_add_instan
 	return __cpuhp_state_add_instance(state, node, false);
 }
 
+static inline int
+cpuhp_state_add_instance_nocalls_cpuslocked(enum cpuhp_state state,
+					    struct hlist_node *node)
+{
+	return __cpuhp_state_add_instance_cpuslocked(state, node, false);
+}
+
 void __cpuhp_remove_state(enum cpuhp_state state, bool invoke);
 void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke);
 
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1412,18 +1412,20 @@ static void cpuhp_rollback_install(int f
 	}
 }
 
-int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
-			       bool invoke)
+int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
+					  struct hlist_node *node,
+					  bool invoke)
 {
 	struct cpuhp_step *sp;
 	int cpu;
 	int ret;
 
+	lockdep_assert_cpus_held();
+
 	sp = cpuhp_get_step(state);
 	if (sp->multi_instance == false)
 		return -EINVAL;
 
-	cpus_read_lock();
 	mutex_lock(&cpuhp_state_mutex);
 
 	if (!invoke || !sp->startup.multi)
@@ -1452,6 +1454,16 @@ int __cpuhp_state_add_instance(enum cpuh
 	hlist_add_head(node, &sp->list);
 unlock:
 	mutex_unlock(&cpuhp_state_mutex);
+	return ret;
+}
+
+int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
+			       bool invoke)
+{
+	int ret;
+
+	cpus_read_lock();
+	ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke);
 	cpus_read_unlock();
 	return ret;
 }