+#endif /* CONFIG_SMP */
+
+/* Boot processor state steps */
+static struct cpuhp_step cpuhp_bp_states[] = {
+ [CPUHP_OFFLINE] = {
+ .name = "offline",
+ .startup = NULL,
+ .teardown = NULL,
+ },
+#ifdef CONFIG_SMP
+ [CPUHP_CREATE_THREADS]= {
+ .name = "threads:create",
+ .startup = smpboot_create_threads,
+ .teardown = NULL,
+ .cant_stop = true,
+ },
+ /*
+ * Preparatory and dead notifiers. Will be replaced once the notifiers
+ * are converted to states.
+ */
+ [CPUHP_NOTIFY_PREPARE] = {
+ .name = "notify:prepare",
+ .startup = notify_prepare,
+ .teardown = notify_dead,
+ .skip_onerr = true,
+ .cant_stop = true,
+ },
+ /* Kicks the plugged cpu into life */
+ [CPUHP_BRINGUP_CPU] = {
+ .name = "cpu:bringup",
+ .startup = bringup_cpu,
+ .teardown = NULL,
+ .cant_stop = true,
+ },
+ /*
+ * Handled on controll processor until the plugged processor manages
+ * this itself.
+ */
+ [CPUHP_TEARDOWN_CPU] = {
+ .name = "cpu:teardown",
+ .startup = NULL,
+ .teardown = takedown_cpu,
+ .cant_stop = true,
+ },
+#endif
+};
+
+/* Application processor state steps */
+static struct cpuhp_step cpuhp_ap_states[] = {
+#ifdef CONFIG_SMP
+ /* Final state before CPU kills itself */
+ [CPUHP_AP_IDLE_DEAD] = {
+ .name = "idle:dead",
+ },
+ /*
+ * Last state before CPU enters the idle loop to die. Transient state
+ * for synchronization.
+ */
+ [CPUHP_AP_OFFLINE] = {
+ .name = "ap:offline",
+ .cant_stop = true,
+ },
+ /*
+ * Low level startup/teardown notifiers. Run with interrupts
+ * disabled. Will be removed once the notifiers are converted to
+ * states.
+ */
+ [CPUHP_AP_NOTIFY_STARTING] = {
+ .name = "notify:starting",
+ .startup = notify_starting,
+ .teardown = notify_dying,
+ .skip_onerr = true,
+ .cant_stop = true,
+ },
+ /* Entry state on starting. Interrupts enabled from here on. Transient
+ * state for synchronsization */
+ [CPUHP_AP_ONLINE] = {
+ .name = "ap:online",
+ },
+ /* Handle smpboot threads park/unpark */
+ [CPUHP_AP_SMPBOOT_THREADS] = {
+ .name = "smpboot:threads",
+ .startup = smpboot_unpark_threads,
+ .teardown = NULL,
+ },
+ /*
+ * Online/down_prepare notifiers. Will be removed once the notifiers
+ * are converted to states.
+ */
+ [CPUHP_AP_NOTIFY_ONLINE] = {
+ .name = "notify:online",
+ .startup = notify_online,
+ .teardown = notify_down_prepare,
+ },
+#endif
+ /*
+ * The dynamically registered state space is here
+ */
+
+ /* CPU is fully up and running. */
+ [CPUHP_ONLINE] = {
+ .name = "online",
+ .startup = NULL,
+ .teardown = NULL,
+ },
+};
+
+/* Sanity check for callbacks */
+static int cpuhp_cb_check(enum cpuhp_state state)
+{
+ if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
+ return -EINVAL;
+ return 0;
+}
+
+static bool cpuhp_is_ap_state(enum cpuhp_state state)
+{
+ /*
+ * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
+ * purposes as that state is handled explicitely in cpu_down.
+ */
+ return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
+}
+
+static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
+{
+ struct cpuhp_step *sp;
+
+ sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
+ return sp + state;
+}
+
+static void cpuhp_store_callbacks(enum cpuhp_state state,
+ const char *name,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu))
+{
+ /* (Un)Install the callbacks for further cpu hotplug operations */
+ struct cpuhp_step *sp;
+
+ mutex_lock(&cpuhp_state_mutex);
+ sp = cpuhp_get_step(state);
+ sp->startup = startup;
+ sp->teardown = teardown;
+ sp->name = name;
+ mutex_unlock(&cpuhp_state_mutex);
+}
+
+static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
+{
+ return cpuhp_get_step(state)->teardown;
+}
+
+/*
+ * Call the startup/teardown function for a step either on the AP or
+ * on the current CPU.
+ */
+static int cpuhp_issue_call(int cpu, enum cpuhp_state state,
+ int (*cb)(unsigned int), bool bringup)
+{
+ int ret;
+
+ if (!cb)
+ return 0;
+ /*
+ * The non AP bound callbacks can fail on bringup. On teardown
+ * e.g. module removal we crash for now.
+ */
+#ifdef CONFIG_SMP
+ if (cpuhp_is_ap_state(state))
+ ret = cpuhp_invoke_ap_callback(cpu, state, cb);
+ else
+ ret = cpuhp_invoke_callback(cpu, state, cb);
+#else
+ ret = cpuhp_invoke_callback(cpu, state, cb);
+#endif
+ BUG_ON(ret && !bringup);
+ return ret;
+}
+
+/*
+ * Called from __cpuhp_setup_state on a recoverable failure.
+ *
+ * Note: The teardown callbacks for rollback are not allowed to fail!
+ */
+static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
+ int (*teardown)(unsigned int cpu))
+{
+ int cpu;
+
+ if (!teardown)
+ return;
+
+ /* Roll back the already executed steps on the other cpus */
+ for_each_present_cpu(cpu) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int cpustate = st->state;
+
+ if (cpu >= failedcpu)
+ break;
+
+ /* Did we invoke the startup call on that cpu ? */
+ if (cpustate >= state)
+ cpuhp_issue_call(cpu, state, teardown, false);
+ }
+}
+
+/*
+ * Returns a free for dynamic slot assignment of the Online state. The states
+ * are protected by the cpuhp_slot_states mutex and an empty slot is identified
+ * by having no name assigned.
+ */
+static int cpuhp_reserve_state(enum cpuhp_state state)
+{
+ enum cpuhp_state i;
+
+ mutex_lock(&cpuhp_state_mutex);
+ for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) {
+ if (cpuhp_ap_states[i].name)
+ continue;
+
+ cpuhp_ap_states[i].name = "Reserved";
+ mutex_unlock(&cpuhp_state_mutex);
+ return i;
+ }
+ mutex_unlock(&cpuhp_state_mutex);
+ WARN(1, "No more dynamic states available for CPU hotplug\n");
+ return -ENOSPC;
+}
+