cpu/hotplug: Split out the state walk into functions

We need that for running callbacks on the AP and the BP.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.374946234@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 3ec86bc..9572ca0 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -329,10 +329,74 @@ static int bringup_cpu(unsigned int cpu)
        return 0;
 }
 
+/*
+ * Hotplug state machine related functions
+ */
+static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st,
+                         struct cpuhp_step *steps)
+{
+       for (st->state++; st->state < st->target; st->state++) {
+               struct cpuhp_step *step = steps + st->state;
+
+               if (!step->skip_onerr)
+                       cpuhp_invoke_callback(cpu, st->state, step->startup);
+       }
+}
+
+static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
+                               struct cpuhp_step *steps, enum cpuhp_state target)
+{
+       enum cpuhp_state prev_state = st->state;
+       int ret = 0;
+
+       for (; st->state > target; st->state--) {
+               struct cpuhp_step *step = steps + st->state;
+
+               ret = cpuhp_invoke_callback(cpu, st->state, step->teardown);
+               if (ret) {
+                       st->target = prev_state;
+                       undo_cpu_down(cpu, st, steps);
+                       break;
+               }
+       }
+       return ret;
+}
+
+static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st,
+                       struct cpuhp_step *steps)
+{
+       for (st->state--; st->state > st->target; st->state--) {
+               struct cpuhp_step *step = steps + st->state;
+
+               if (!step->skip_onerr)
+                       cpuhp_invoke_callback(cpu, st->state, step->teardown);
+       }
+}
+
+static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
+                             struct cpuhp_step *steps, enum cpuhp_state target)
+{
+       enum cpuhp_state prev_state = st->state;
+       int ret = 0;
+
+       while (st->state < target) {
+               struct cpuhp_step *step;
+
+               st->state++;
+               step = steps + st->state;
+               ret = cpuhp_invoke_callback(cpu, st->state, step->startup);
+               if (ret) {
+                       st->target = prev_state;
+                       undo_cpu_up(cpu, st, steps);
+                       break;
+               }
+       }
+       return ret;
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 EXPORT_SYMBOL(register_cpu_notifier);
 EXPORT_SYMBOL(__register_cpu_notifier);
-
 void unregister_cpu_notifier(struct notifier_block *nb)
 {
        cpu_maps_update_begin();
@@ -537,15 +601,6 @@ static int notify_dead(unsigned int cpu)
 #endif
 
 #ifdef CONFIG_HOTPLUG_CPU
-static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
-{
-       for (st->state++; st->state < st->target; st->state++) {
-               struct cpuhp_step *step = cpuhp_bp_states + st->state;
-
-               if (!step->skip_onerr)
-                       cpuhp_invoke_callback(cpu, st->state, step->startup);
-       }
-}
 
 /* Requires cpu_add_remove_lock to be held */
 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
@@ -567,16 +622,8 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
 
        prev_state = st->state;
        st->target = target;
-       for (; st->state > st->target; st->state--) {
-               struct cpuhp_step *step = cpuhp_bp_states + st->state;
+       ret = cpuhp_down_callbacks(cpu, st, cpuhp_bp_states, target);
 
-               ret = cpuhp_invoke_callback(cpu, st->state, step->teardown);
-               if (ret) {
-                       st->target = prev_state;
-                       undo_cpu_down(cpu, st);
-                       break;
-               }
-       }
        hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
 
        cpu_hotplug_done();
@@ -645,22 +692,12 @@ static int cpuhp_set_cpu_active(unsigned int cpu)
        return 0;
 }
 
-static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
-{
-       for (st->state--; st->state > st->target; st->state--) {
-               struct cpuhp_step *step = cpuhp_bp_states + st->state;
-
-               if (!step->skip_onerr)
-                       cpuhp_invoke_callback(cpu, st->state, step->teardown);
-       }
-}
-
 /* Requires cpu_add_remove_lock to be held */
 static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 {
        struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
        struct task_struct *idle;
-       int prev_state, ret = 0;
+       int ret = 0;
 
        cpu_hotplug_begin();
 
@@ -687,20 +724,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 
        cpuhp_tasks_frozen = tasks_frozen;
 
-       prev_state = st->state;
        st->target = target;
-       while (st->state < st->target) {
-               struct cpuhp_step *step;
-
-               st->state++;
-               step = cpuhp_bp_states + st->state;
-               ret = cpuhp_invoke_callback(cpu, st->state, step->startup);
-               if (ret) {
-                       st->target = prev_state;
-                       undo_cpu_up(cpu, st);
-                       break;
-               }
-       }
+       ret = cpuhp_up_callbacks(cpu, st, cpuhp_bp_states, target);
 out:
        cpu_hotplug_done();
        return ret;