Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull SMP hotplug notifier removal from Thomas Gleixner:
 "This is the final cleanup of the hotplug notifier infrastructure. The
  series has been reintgrated in the last two days because there came a
  new driver using the old infrastructure via the SCSI tree.

  Summary:

   - convert the last leftover drivers utilizing notifiers

   - fixup for a completely broken hotplug user

   - prevent setup of already used states

   - removal of the notifiers

   - treewide cleanup of hotplug state names

   - consolidation of state space

  There is a sphinx based documentation pending, but that needs review
  from the documentation folks"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/armada-xp: Consolidate hotplug state space
  irqchip/gic: Consolidate hotplug state space
  coresight/etm3/4x: Consolidate hotplug state space
  cpu/hotplug: Cleanup state names
  cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions
  staging/lustre/libcfs: Convert to hotplug state machine
  scsi/bnx2i: Convert to hotplug state machine
  scsi/bnx2fc: Convert to hotplug state machine
  cpu/hotplug: Prevent overwriting of callbacks
  x86/msr: Remove bogus cleanup from the error path
  bus: arm-ccn: Prevent hotplug callback leak
  perf/x86/intel/cstate: Prevent hotplug callback leak
  ARM/imx/mmcd: Fix broken cpu hotplug handling
  scsi: qedi: Convert to hotplug state machine

1 files changed, 51 insertions, 184 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 5339aca811d2..042fd7e8e030 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -183,23 +183,16 @@ EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);
 /*
  * The following two APIs (cpu_maps_update_begin/done) must be used when
  * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
- * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
- * hotplug callback (un)registration performed using __register_cpu_notifier()
- * or __unregister_cpu_notifier().
  */
 void cpu_maps_update_begin(void)
 {
 	mutex_lock(&cpu_add_remove_lock);
 }
-EXPORT_SYMBOL(cpu_notifier_register_begin);
 
 void cpu_maps_update_done(void)
 {
 	mutex_unlock(&cpu_add_remove_lock);
 }
-EXPORT_SYMBOL(cpu_notifier_register_done);
-
-static RAW_NOTIFIER_HEAD(cpu_chain);
 
 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
  * Should always be manipulated under cpu_add_remove_lock
@@ -349,66 +342,7 @@ void cpu_hotplug_enable(void)
 EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 #endif	/* CONFIG_HOTPLUG_CPU */
 
-/* Need to know about CPUs going up/down? */
-int register_cpu_notifier(struct notifier_block *nb)
-{
-	int ret;
-	cpu_maps_update_begin();
-	ret = raw_notifier_chain_register(&cpu_chain, nb);
-	cpu_maps_update_done();
-	return ret;
-}
-
-int __register_cpu_notifier(struct notifier_block *nb)
-{
-	return raw_notifier_chain_register(&cpu_chain, nb);
-}
-
-static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call,
-			int *nr_calls)
-{
-	unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0;
-	void *hcpu = (void *)(long)cpu;
-
-	int ret;
-
-	ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call,
-					nr_calls);
-
-	return notifier_to_errno(ret);
-}
-
-static int cpu_notify(unsigned long val, unsigned int cpu)
-{
-	return __cpu_notify(val, cpu, -1, NULL);
-}
-
-static void cpu_notify_nofail(unsigned long val, unsigned int cpu)
-{
-	BUG_ON(cpu_notify(val, cpu));
-}
-
 /* Notifier wrappers for transitioning to state machine */
-static int notify_prepare(unsigned int cpu)
-{
-	int nr_calls = 0;
-	int ret;
-
-	ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls);
-	if (ret) {
-		nr_calls--;
-		printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
-				__func__, cpu);
-		__cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL);
-	}
-	return ret;
-}
-
-static int notify_online(unsigned int cpu)
-{
-	cpu_notify(CPU_ONLINE, cpu);
-	return 0;
-}
 
 static int bringup_wait_for_ap(unsigned int cpu)
 {
@@ -433,10 +367,8 @@ static int bringup_cpu(unsigned int cpu)
 	/* Arch-specific enabling code. */
 	ret = __cpu_up(cpu, idle);
 	irq_unlock_sparse();
-	if (ret) {
-		cpu_notify(CPU_UP_CANCELED, cpu);
+	if (ret)
 		return ret;
-	}
 	ret = bringup_wait_for_ap(cpu);
 	BUG_ON(!cpu_online(cpu));
 	return ret;
@@ -565,11 +497,6 @@ static void cpuhp_thread_fun(unsigned int cpu)
 		BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);
 
 		undo_cpu_down(cpu, st);
-		/*
-		 * This is a momentary workaround to keep the notifier users
-		 * happy. Will go away once we got rid of the notifiers.
-		 */
-		cpu_notify_nofail(CPU_DOWN_FAILED, cpu);
 		st->rollback = false;
 	} else {
 		/* Cannot happen .... */
@@ -659,22 +586,6 @@ void __init cpuhp_threads_init(void)
 	kthread_unpark(this_cpu_read(cpuhp_state.thread));
 }
 
-EXPORT_SYMBOL(register_cpu_notifier);
-EXPORT_SYMBOL(__register_cpu_notifier);
-void unregister_cpu_notifier(struct notifier_block *nb)
-{
-	cpu_maps_update_begin();
-	raw_notifier_chain_unregister(&cpu_chain, nb);
-	cpu_maps_update_done();
-}
-EXPORT_SYMBOL(unregister_cpu_notifier);
-
-void __unregister_cpu_notifier(struct notifier_block *nb)
-{
-	raw_notifier_chain_unregister(&cpu_chain, nb);
-}
-EXPORT_SYMBOL(__unregister_cpu_notifier);
-
 #ifdef CONFIG_HOTPLUG_CPU
 /**
  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
@@ -741,20 +652,6 @@ static inline void check_for_tasks(int dead_cpu)
 	read_unlock(&tasklist_lock);
 }
 
-static int notify_down_prepare(unsigned int cpu)
-{
-	int err, nr_calls = 0;
-
-	err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);
-	if (err) {
-		nr_calls--;
-		__cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);
-		pr_warn("%s: attempt to take down CPU %u failed\n",
-				__func__, cpu);
-	}
-	return err;
-}
-
 /* Take this CPU down. */
 static int take_cpu_down(void *_param)
 {
@@ -833,13 +730,6 @@ static int takedown_cpu(unsigned int cpu)
 	return 0;
 }
 
-static int notify_dead(unsigned int cpu)
-{
-	cpu_notify_nofail(CPU_DEAD, cpu);
-	check_for_tasks(cpu);
-	return 0;
-}
-
 static void cpuhp_complete_idle_dead(void *arg)
 {
 	struct cpuhp_cpu_state *st = arg;
@@ -863,9 +753,7 @@ void cpuhp_report_idle_dead(void)
 }
 
 #else
-#define notify_down_prepare	NULL
 #define takedown_cpu		NULL
-#define notify_dead		NULL
 #endif
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -924,9 +812,6 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
 	hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
 out:
 	cpu_hotplug_done();
-	/* This post dead nonsense must die */
-	if (!ret && hasdied)
-		cpu_notify_nofail(CPU_POST_DEAD, cpu);
 	return ret;
 }
 
@@ -1292,17 +1177,6 @@ static struct cpuhp_step cpuhp_bp_states[] = {
 		.teardown.single	= rcutree_dead_cpu,
 	},
 	/*
-	 * Preparatory and dead notifiers. Will be replaced once the notifiers
-	 * are converted to states.
-	 */
-	[CPUHP_NOTIFY_PREPARE] = {
-		.name			= "notify:prepare",
-		.startup.single		= notify_prepare,
-		.teardown.single	= notify_dead,
-		.skip_onerr		= true,
-		.cant_stop		= true,
-	},
-	/*
 	 * On the tear-down path, timers_dead_cpu() must be invoked
 	 * before blk_mq_queue_reinit_notify() from notify_dead(),
 	 * otherwise a RCU stall occurs.
@@ -1391,17 +1265,6 @@ static struct cpuhp_step cpuhp_ap_states[] = {
 		.startup.single		= rcutree_online_cpu,
 		.teardown.single	= rcutree_offline_cpu,
 	},
-
-	/*
-	 * Online/down_prepare notifiers. Will be removed once the notifiers
-	 * are converted to states.
-	 */
-	[CPUHP_AP_NOTIFY_ONLINE] = {
-		.name			= "notify:online",
-		.startup.single		= notify_online,
-		.teardown.single	= notify_down_prepare,
-		.skip_onerr		= true,
-	},
 #endif
 	/*
 	 * The dynamically registered state space is here
@@ -1432,23 +1295,53 @@ static int cpuhp_cb_check(enum cpuhp_state state)
 	return 0;
 }
 
-static void cpuhp_store_callbacks(enum cpuhp_state state,
-				  const char *name,
-				  int (*startup)(unsigned int cpu),
-				  int (*teardown)(unsigned int cpu),
-				  bool multi_instance)
+/*
+ * 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;
+
+	for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) {
+		if (!cpuhp_ap_states[i].name)
+			return i;
+	}
+	WARN(1, "No more dynamic states available for CPU hotplug\n");
+	return -ENOSPC;
+}
+
+static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
+				 int (*startup)(unsigned int cpu),
+				 int (*teardown)(unsigned int cpu),
+				 bool multi_instance)
 {
 	/* (Un)Install the callbacks for further cpu hotplug operations */
 	struct cpuhp_step *sp;
+	int ret = 0;
 
 	mutex_lock(&cpuhp_state_mutex);
+
+	if (state == CPUHP_AP_ONLINE_DYN) {
+		ret = cpuhp_reserve_state(state);
+		if (ret < 0)
+			goto out;
+		state = ret;
+	}
 	sp = cpuhp_get_step(state);
+	if (name && sp->name) {
+		ret = -EBUSY;
+		goto out;
+	}
 	sp->startup.single = startup;
 	sp->teardown.single = teardown;
 	sp->name = name;
 	sp->multi_instance = multi_instance;
 	INIT_HLIST_HEAD(&sp->list);
+out:
 	mutex_unlock(&cpuhp_state_mutex);
+	return ret;
 }
 
 static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
@@ -1509,29 +1402,6 @@ static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
 	}
 }
 
-/*
- * 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;
-}
-
 int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
 			       bool invoke)
 {
@@ -1580,11 +1450,13 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
 
 /**
  * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
- * @state:	The state to setup
- * @invoke:	If true, the startup function is invoked for cpus where
- *		cpu state >= @state
- * @startup:	startup callback function
- * @teardown:	teardown callback function
+ * @state:		The state to setup
+ * @invoke:		If true, the startup function is invoked for cpus where
+ *			cpu state >= @state
+ * @startup:		startup callback function
+ * @teardown:		teardown callback function
+ * @multi_instance:	State is set up for multiple instances which get
+ *			added afterwards.
  *
  * Returns:
  *   On success:
@@ -1599,25 +1471,16 @@ int __cpuhp_setup_state(enum cpuhp_state state,
 			bool multi_instance)
 {
 	int cpu, ret = 0;
-	int dyn_state = 0;
 
 	if (cpuhp_cb_check(state) || !name)
 		return -EINVAL;
 
 	get_online_cpus();
 
-	/* currently assignments for the ONLINE state are possible */
-	if (state == CPUHP_AP_ONLINE_DYN) {
-		dyn_state = 1;
-		ret = cpuhp_reserve_state(state);
-		if (ret < 0)
-			goto out;
-		state = ret;
-	}
+	ret = cpuhp_store_callbacks(state, name, startup, teardown,
+				    multi_instance);
 
-	cpuhp_store_callbacks(state, name, startup, teardown, multi_instance);
-
-	if (!invoke || !startup)
+	if (ret || !invoke || !startup)
 		goto out;
 
 	/*
@@ -1641,7 +1504,11 @@ int __cpuhp_setup_state(enum cpuhp_state state,
 	}
 out:
 	put_online_cpus();
-	if (!ret && dyn_state)
+	/*
+	 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
+	 * dynamically allocated state in case of success.
+	 */
+	if (!ret && state == CPUHP_AP_ONLINE_DYN)
 		return state;
 	return ret;
 }