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cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions
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hotcpu_notifier(), cpu_notifier(), __hotcpu_notifier(), __cpu_notifier(),
register_hotcpu_notifier(), register_cpu_notifier(),
__register_hotcpu_notifier(), __register_cpu_notifier(),
unregister_hotcpu_notifier(), unregister_cpu_notifier(),
__unregister_hotcpu_notifier(), __unregister_cpu_notifier()

are unused now. Remove them and all related code.

Remove also the now pointless cpu notifier error injection mechanism. The
states can be executed step by step and error rollback is the same as cpu
down, so any state transition can be tested w/o requiring the notifier
error injection.

Some CPU hotplug states are kept as they are (ab)used for hotplug state
tracking.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161221192112.005642358@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Thomas Gleixner committed Dec 25, 2016
1 parent 7b73796 commit 530e9b7
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Showing 6 changed files with 1 addition and 340 deletions.
90 changes: 0 additions & 90 deletions include/linux/cpu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -57,9 +57,6 @@ struct notifier_block;

#define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */
#define CPU_UP_PREPARE 0x0003 /* CPU (unsigned)v coming up */
#define CPU_UP_CANCELED 0x0004 /* CPU (unsigned)v NOT coming up */
#define CPU_DOWN_PREPARE 0x0005 /* CPU (unsigned)v going down */
#define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */
#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */
#define CPU_POST_DEAD 0x0009 /* CPU (unsigned)v dead, cpu_hotplug
* lock is dropped */
Expand All @@ -80,80 +77,14 @@ struct notifier_block;

#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
/* Need to know about CPUs going up/down? */
#if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE)
#define cpu_notifier(fn, pri) { \
static struct notifier_block fn##_nb = \
{ .notifier_call = fn, .priority = pri }; \
register_cpu_notifier(&fn##_nb); \
}

#define __cpu_notifier(fn, pri) { \
static struct notifier_block fn##_nb = \
{ .notifier_call = fn, .priority = pri }; \
__register_cpu_notifier(&fn##_nb); \
}

extern int register_cpu_notifier(struct notifier_block *nb);
extern int __register_cpu_notifier(struct notifier_block *nb);
extern void unregister_cpu_notifier(struct notifier_block *nb);
extern void __unregister_cpu_notifier(struct notifier_block *nb);

#else /* #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */
#define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
#define __cpu_notifier(fn, pri) do { (void)(fn); } while (0)

static inline int register_cpu_notifier(struct notifier_block *nb)
{
return 0;
}

static inline int __register_cpu_notifier(struct notifier_block *nb)
{
return 0;
}

static inline void unregister_cpu_notifier(struct notifier_block *nb)
{
}

static inline void __unregister_cpu_notifier(struct notifier_block *nb)
{
}
#endif

int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);

#define cpu_notifier_register_begin cpu_maps_update_begin
#define cpu_notifier_register_done cpu_maps_update_done

#else /* CONFIG_SMP */
#define cpuhp_tasks_frozen 0

#define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
#define __cpu_notifier(fn, pri) do { (void)(fn); } while (0)

static inline int register_cpu_notifier(struct notifier_block *nb)
{
return 0;
}

static inline int __register_cpu_notifier(struct notifier_block *nb)
{
return 0;
}

static inline void unregister_cpu_notifier(struct notifier_block *nb)
{
}

static inline void __unregister_cpu_notifier(struct notifier_block *nb)
{
}

static inline void cpu_maps_update_begin(void)
{
}
Expand All @@ -162,14 +93,6 @@ static inline void cpu_maps_update_done(void)
{
}

static inline void cpu_notifier_register_begin(void)
{
}

static inline void cpu_notifier_register_done(void)
{
}

#endif /* CONFIG_SMP */
extern struct bus_type cpu_subsys;

Expand All @@ -182,12 +105,6 @@ extern void get_online_cpus(void);
extern void put_online_cpus(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
#define hotcpu_notifier(fn, pri) cpu_notifier(fn, pri)
#define __hotcpu_notifier(fn, pri) __cpu_notifier(fn, pri)
#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
#define __register_hotcpu_notifier(nb) __register_cpu_notifier(nb)
#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
#define __unregister_hotcpu_notifier(nb) __unregister_cpu_notifier(nb)
void clear_tasks_mm_cpumask(int cpu);
int cpu_down(unsigned int cpu);

Expand All @@ -199,13 +116,6 @@ static inline void cpu_hotplug_done(void) {}
#define put_online_cpus() do { } while (0)
#define cpu_hotplug_disable() do { } while (0)
#define cpu_hotplug_enable() do { } while (0)
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
#define __hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
/* These aren't inline functions due to a GCC bug. */
#define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
#define __register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
#define unregister_hotcpu_notifier(nb) ({ (void)(nb); })
#define __unregister_hotcpu_notifier(nb) ({ (void)(nb); })
#endif /* CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_PM_SLEEP_SMP
Expand Down
3 changes: 0 additions & 3 deletions include/linux/cpuhotplug.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,6 @@ enum cpuhp_state {
CPUHP_POWERPC_MMU_CTX_PREPARE,
CPUHP_XEN_PREPARE,
CPUHP_XEN_EVTCHN_PREPARE,
CPUHP_NOTIFY_PREPARE,
CPUHP_ARM_SHMOBILE_SCU_PREPARE,
CPUHP_SH_SH3X_PREPARE,
CPUHP_BLK_MQ_PREPARE,
Expand All @@ -74,7 +73,6 @@ enum cpuhp_state {
CPUHP_KVM_PPC_BOOK3S_PREPARE,
CPUHP_ZCOMP_PREPARE,
CPUHP_TIMERS_DEAD,
CPUHP_NOTF_ERR_INJ_PREPARE,
CPUHP_MIPS_SOC_PREPARE,
CPUHP_BRINGUP_CPU,
CPUHP_AP_IDLE_DEAD,
Expand Down Expand Up @@ -145,7 +143,6 @@ enum cpuhp_state {
CPUHP_AP_PERF_ARM_L2X0_ONLINE,
CPUHP_AP_WORKQUEUE_ONLINE,
CPUHP_AP_RCUTREE_ONLINE,
CPUHP_AP_NOTIFY_ONLINE,
CPUHP_AP_ONLINE_DYN,
CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,
CPUHP_AP_X86_HPET_ONLINE,
Expand Down
139 changes: 1 addition & 138 deletions kernel/cpu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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)
{
Expand All @@ -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;
Expand Down Expand Up @@ -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 .... */
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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)
{
Expand Down Expand Up @@ -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;
Expand All @@ -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
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -1291,17 +1176,6 @@ static struct cpuhp_step cpuhp_bp_states[] = {
.startup.single = rcutree_prepare_cpu,
.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(),
Expand Down Expand Up @@ -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
Expand Down
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