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

2 files changed, 24 insertions, 3 deletions

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 4fac564dde70..df3d2719a796 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -240,6 +240,8 @@ static inline int cpuhp_setup_state_multi(enum cpuhp_state state,
 
 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
@@ -272,6 +274,13 @@ static inline int cpuhp_state_add_instance_nocalls(enum cpuhp_state state,
         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);
 
diff --git a/kernel/cpu.c b/kernel/cpu.c
index dc27c5a28153..e4389ac55b65 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1413,18 +1413,20 @@ static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
         }
 }
 
-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)
@@ -1453,6 +1455,16 @@ add_node:
         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;
 }