rcutorture: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 14 insertions, 38 deletions

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 971e2b138063..dc9814860645 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1362,12 +1362,12 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
                  onoff_interval, onoff_holdoff);
 }
 
-static void rcutorture_booster_cleanup(int cpu)
+static int rcutorture_booster_cleanup(unsigned int cpu)
 {
         struct task_struct *t;
 
         if (boost_tasks[cpu] == NULL)
-                return;
+                return 0;
         mutex_lock(&boost_mutex);
         t = boost_tasks[cpu];
         boost_tasks[cpu] = NULL;
@@ -1375,9 +1375,10 @@ static void rcutorture_booster_cleanup(int cpu)
 
         /* This must be outside of the mutex, otherwise deadlock! */
         torture_stop_kthread(rcu_torture_boost, t);
+        return 0;
 }
 
-static int rcutorture_booster_init(int cpu)
+static int rcutorture_booster_init(unsigned int cpu)
 {
         int retval;
 
@@ -1577,28 +1578,7 @@ static void rcu_torture_barrier_cleanup(void)
         }
 }
 
-static int rcutorture_cpu_notify(struct notifier_block *self,
-                                 unsigned long action, void *hcpu)
-{
-        long cpu = (long)hcpu;
-
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_ONLINE:
-        case CPU_DOWN_FAILED:
-                (void)rcutorture_booster_init(cpu);
-                break;
-        case CPU_DOWN_PREPARE:
-                rcutorture_booster_cleanup(cpu);
-                break;
-        default:
-                break;
-        }
-        return NOTIFY_OK;
-}
-
-static struct notifier_block rcutorture_cpu_nb = {
-        .notifier_call = rcutorture_cpu_notify,
-};
+static enum cpuhp_state rcutor_hp;
 
 static void
 rcu_torture_cleanup(void)
@@ -1638,11 +1618,8 @@ rcu_torture_cleanup(void)
         for (i = 0; i < ncbflooders; i++)
                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
         if ((test_boost == 1 && cur_ops->can_boost) ||
-            test_boost == 2) {
-                unregister_cpu_notifier(&rcutorture_cpu_nb);
-                for_each_possible_cpu(i)
-                        rcutorture_booster_cleanup(i);
-        }
+            test_boost == 2)
+                cpuhp_remove_state(rcutor_hp);
 
         /*
          * Wait for all RCU callbacks to fire, then do flavor-specific
@@ -1869,14 +1846,13 @@ rcu_torture_init(void)
             test_boost == 2) {
 
                 boost_starttime = jiffies + test_boost_interval * HZ;
-                register_cpu_notifier(&rcutorture_cpu_nb);
-                for_each_possible_cpu(i) {
-                        if (cpu_is_offline(i))
-                                continue;  /* Heuristic: CPU can go offline. */
-                        firsterr = rcutorture_booster_init(i);
-                        if (firsterr)
-                                goto unwind;
-                }
+
+                firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
+                                             rcutorture_booster_init,
+                                             rcutorture_booster_cleanup);
+                if (firsterr < 0)
+                        goto unwind;
+                rcutor_hp = firsterr;
         }
         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
         if (firsterr)