CPU (hotplug) updates:

- Support for locked CSD objects in smp_call_function_single_async()
     which allows to simplify callsites in the scheduler core and MIPS
 
   - Treewide consolidation of CPU hotplug functions which ensures the
     consistency between the sysfs interface and kernel state. The low level
     functions cpu_up/down() are now confined to the core code and not
     longer accessible from random code.
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Merge tag 'smp-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core SMP updates from Thomas Gleixner:
 "CPU (hotplug) updates:

   - Support for locked CSD objects in smp_call_function_single_async()
     which allows to simplify callsites in the scheduler core and MIPS

   - Treewide consolidation of CPU hotplug functions which ensures the
     consistency between the sysfs interface and kernel state. The low
     level functions cpu_up/down() are now confined to the core code and
     not longer accessible from random code"

* tag 'smp-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
  cpu/hotplug: Ignore pm_wakeup_pending() for disable_nonboot_cpus()
  cpu/hotplug: Hide cpu_up/down()
  cpu/hotplug: Move bringup of secondary CPUs out of smp_init()
  torture: Replace cpu_up/down() with add/remove_cpu()
  firmware: psci: Replace cpu_up/down() with add/remove_cpu()
  xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()
  parisc: Replace cpu_up/down() with add/remove_cpu()
  sparc: Replace cpu_up/down() with add/remove_cpu()
  powerpc: Replace cpu_up/down() with add/remove_cpu()
  x86/smp: Replace cpu_up/down() with add/remove_cpu()
  arm64: hibernate: Use bringup_hibernate_cpu()
  cpu/hotplug: Provide bringup_hibernate_cpu()
  arm64: Use reboot_cpu instead of hardconding it to 0
  arm64: Don't use disable_nonboot_cpus()
  ARM: Use reboot_cpu instead of hardcoding it to 0
  ARM: Don't use disable_nonboot_cpus()
  ia64: Replace cpu_down() with smp_shutdown_nonboot_cpus()
  cpu/hotplug: Create a new function to shutdown nonboot cpus
  cpu/hotplug: Add new {add,remove}_cpu() functions
  sched/core: Remove rq.hrtick_csd_pending
  ...
This commit is contained in:
Linus Torvalds 2020-03-30 18:06:39 -07:00
commit 992a1a3b45
20 changed files with 194 additions and 97 deletions

View File

@ -88,11 +88,11 @@ void soft_restart(unsigned long addr)
* to execute e.g. a RAM-based pin loop is not sufficient. This allows the
* kexec'd kernel to use any and all RAM as it sees fit, without having to
* avoid any code or data used by any SW CPU pin loop. The CPU hotplug
* functionality embodied in disable_nonboot_cpus() to achieve this.
* functionality embodied in smp_shutdown_nonboot_cpus() to achieve this.
*/
void machine_shutdown(void)
{
disable_nonboot_cpus();
smp_shutdown_nonboot_cpus(reboot_cpu);
}
/*

View File

@ -166,14 +166,11 @@ int arch_hibernation_header_restore(void *addr)
sleep_cpu = -EINVAL;
return -EINVAL;
}
if (!cpu_online(sleep_cpu)) {
pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
ret = cpu_up(sleep_cpu);
if (ret) {
pr_err("Failed to bring hibernate-CPU up!\n");
sleep_cpu = -EINVAL;
return ret;
}
ret = bringup_hibernate_cpu(sleep_cpu);
if (ret) {
sleep_cpu = -EINVAL;
return ret;
}
resume_hdr = *hdr;

View File

@ -141,11 +141,11 @@ void arch_cpu_idle_dead(void)
* to execute e.g. a RAM-based pin loop is not sufficient. This allows the
* kexec'd kernel to use any and all RAM as it sees fit, without having to
* avoid any code or data used by any SW CPU pin loop. The CPU hotplug
* functionality embodied in disable_nonboot_cpus() to achieve this.
* functionality embodied in smpt_shutdown_nonboot_cpus() to achieve this.
*/
void machine_shutdown(void)
{
disable_nonboot_cpus();
smp_shutdown_nonboot_cpus(reboot_cpu);
}
/*

View File

@ -646,14 +646,8 @@ cpu_halt (void)
void machine_shutdown(void)
{
#ifdef CONFIG_HOTPLUG_CPU
int cpu;
smp_shutdown_nonboot_cpus(reboot_cpu);
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id())
cpu_down(cpu);
}
#endif
#ifdef CONFIG_KEXEC
kexec_disable_iosapic();
#endif

View File

@ -696,29 +696,22 @@ EXPORT_SYMBOL(flush_tlb_one);
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static DEFINE_PER_CPU(atomic_t, tick_broadcast_count);
static DEFINE_PER_CPU(call_single_data_t, tick_broadcast_csd);
void tick_broadcast(const struct cpumask *mask)
{
atomic_t *count;
call_single_data_t *csd;
int cpu;
for_each_cpu(cpu, mask) {
count = &per_cpu(tick_broadcast_count, cpu);
csd = &per_cpu(tick_broadcast_csd, cpu);
if (atomic_inc_return(count) == 1)
smp_call_function_single_async(cpu, csd);
smp_call_function_single_async(cpu, csd);
}
}
static void tick_broadcast_callee(void *info)
{
int cpu = smp_processor_id();
tick_receive_broadcast();
atomic_set(&per_cpu(tick_broadcast_count, cpu), 0);
}
static int __init tick_broadcast_init(void)

View File

@ -212,7 +212,7 @@ static int __init processor_probe(struct parisc_device *dev)
#ifdef CONFIG_SMP
if (cpuid) {
set_cpu_present(cpuid, true);
cpu_up(cpuid);
add_cpu(cpuid);
}
#endif

View File

@ -212,7 +212,7 @@ static void wake_offline_cpus(void)
if (!cpu_online(cpu)) {
printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
cpu);
WARN_ON(cpu_up(cpu));
WARN_ON(add_cpu(cpu));
}
}
}

View File

@ -555,7 +555,7 @@ static int dr_cpu_configure(struct ds_info *dp, struct ds_cap_state *cp,
printk(KERN_INFO "ds-%llu: Starting cpu %d...\n",
dp->id, cpu);
err = cpu_up(cpu);
err = add_cpu(cpu);
if (err) {
__u32 res = DR_CPU_RES_FAILURE;
__u32 stat = DR_CPU_STAT_UNCONFIGURED;
@ -611,7 +611,7 @@ static int dr_cpu_unconfigure(struct ds_info *dp,
printk(KERN_INFO "ds-%llu: Shutting down cpu %d...\n",
dp->id, cpu);
err = cpu_down(cpu);
err = remove_cpu(cpu);
if (err)
dr_cpu_mark(resp, cpu, ncpus,
DR_CPU_RES_FAILURE,

View File

@ -59,39 +59,29 @@ __setup("cpu0_hotplug", enable_cpu0_hotplug);
*/
int _debug_hotplug_cpu(int cpu, int action)
{
struct device *dev = get_cpu_device(cpu);
int ret;
if (!cpu_is_hotpluggable(cpu))
return -EINVAL;
lock_device_hotplug();
switch (action) {
case 0:
ret = cpu_down(cpu);
if (!ret) {
ret = remove_cpu(cpu);
if (!ret)
pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
dev->offline = true;
kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
} else
else
pr_debug("Can't offline CPU%d.\n", cpu);
break;
case 1:
ret = cpu_up(cpu);
if (!ret) {
dev->offline = false;
kobject_uevent(&dev->kobj, KOBJ_ONLINE);
} else {
ret = add_cpu(cpu);
if (ret)
pr_debug("Can't online CPU%d.\n", cpu);
}
break;
default:
ret = -EINVAL;
}
unlock_device_hotplug();
return ret;
}

View File

@ -386,7 +386,7 @@ static void enter_uniprocessor(void)
put_online_cpus();
for_each_cpu(cpu, downed_cpus) {
err = cpu_down(cpu);
err = remove_cpu(cpu);
if (!err)
pr_info("CPU%d is down.\n", cpu);
else
@ -406,7 +406,7 @@ static void leave_uniprocessor(void)
return;
pr_notice("Re-enabling CPUs...\n");
for_each_cpu(cpu, downed_cpus) {
err = cpu_up(cpu);
err = add_cpu(cpu);
if (!err)
pr_info("enabled CPU%d.\n", cpu);
else

View File

@ -132,7 +132,7 @@ void __init xen_smp_cpus_done(unsigned int max_cpus)
if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS)
continue;
rc = cpu_down(cpu);
rc = remove_cpu(cpu);
if (rc == 0) {
/*

View File

@ -55,7 +55,7 @@ static int cpu_subsys_online(struct device *dev)
if (from_nid == NUMA_NO_NODE)
return -ENODEV;
ret = cpu_up(cpuid);
ret = cpu_device_up(dev);
/*
* When hot adding memory to memoryless node and enabling a cpu
* on the node, node number of the cpu may internally change.
@ -69,7 +69,7 @@ static int cpu_subsys_online(struct device *dev)
static int cpu_subsys_offline(struct device *dev)
{
return cpu_down(dev->id);
return cpu_device_down(dev);
}
void unregister_cpu(struct cpu *cpu)

View File

@ -84,7 +84,7 @@ static unsigned int down_and_up_cpus(const struct cpumask *cpus,
/* Try to power down all CPUs in the mask. */
for_each_cpu(cpu, cpus) {
int ret = cpu_down(cpu);
int ret = remove_cpu(cpu);
/*
* cpu_down() checks the number of online CPUs before the TOS
@ -116,7 +116,7 @@ static unsigned int down_and_up_cpus(const struct cpumask *cpus,
/* Try to power up all the CPUs that have been offlined. */
for_each_cpu(cpu, offlined_cpus) {
int ret = cpu_up(cpu);
int ret = add_cpu(cpu);
if (ret != 0) {
pr_err("Error occurred (%d) while trying "

View File

@ -94,7 +94,7 @@ static int setup_cpu_watcher(struct notifier_block *notifier,
for_each_possible_cpu(cpu) {
if (vcpu_online(cpu) == 0) {
(void)cpu_down(cpu);
device_offline(get_cpu_device(cpu));
set_cpu_present(cpu, false);
}
}

View File

@ -88,10 +88,13 @@ extern ssize_t arch_cpu_release(const char *, size_t);
#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
int cpu_up(unsigned int cpu);
int add_cpu(unsigned int cpu);
int cpu_device_up(struct device *dev);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);
int bringup_hibernate_cpu(unsigned int sleep_cpu);
void bringup_nonboot_cpus(unsigned int setup_max_cpus);
#else /* CONFIG_SMP */
#define cpuhp_tasks_frozen 0
@ -117,7 +120,9 @@ extern void lockdep_assert_cpus_held(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
int cpu_down(unsigned int cpu);
int remove_cpu(unsigned int cpu);
int cpu_device_down(struct device *dev);
extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
#else /* CONFIG_HOTPLUG_CPU */
@ -129,6 +134,7 @@ static inline int cpus_read_trylock(void) { return true; }
static inline void lockdep_assert_cpus_held(void) { }
static inline void cpu_hotplug_disable(void) { }
static inline void cpu_hotplug_enable(void) { }
static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
#endif /* !CONFIG_HOTPLUG_CPU */
/* Wrappers which go away once all code is converted */
@ -138,12 +144,18 @@ static inline void get_online_cpus(void) { cpus_read_lock(); }
static inline void put_online_cpus(void) { cpus_read_unlock(); }
#ifdef CONFIG_PM_SLEEP_SMP
extern int freeze_secondary_cpus(int primary);
int __freeze_secondary_cpus(int primary, bool suspend);
static inline int freeze_secondary_cpus(int primary)
{
return __freeze_secondary_cpus(primary, true);
}
static inline int disable_nonboot_cpus(void)
{
return freeze_secondary_cpus(0);
return __freeze_secondary_cpus(0, false);
}
extern void enable_nonboot_cpus(void);
void enable_nonboot_cpus(void);
static inline int suspend_disable_secondary_cpus(void)
{

View File

@ -1041,7 +1041,7 @@ static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target)
return _cpu_down(cpu, 0, target);
}
static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
static int cpu_down(unsigned int cpu, enum cpuhp_state target)
{
int err;
@ -1051,11 +1051,72 @@ static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
return err;
}
int cpu_down(unsigned int cpu)
/**
* cpu_device_down - Bring down a cpu device
* @dev: Pointer to the cpu device to offline
*
* This function is meant to be used by device core cpu subsystem only.
*
* Other subsystems should use remove_cpu() instead.
*/
int cpu_device_down(struct device *dev)
{
return do_cpu_down(cpu, CPUHP_OFFLINE);
return cpu_down(dev->id, CPUHP_OFFLINE);
}
int remove_cpu(unsigned int cpu)
{
int ret;
lock_device_hotplug();
ret = device_offline(get_cpu_device(cpu));
unlock_device_hotplug();
return ret;
}
EXPORT_SYMBOL_GPL(remove_cpu);
void smp_shutdown_nonboot_cpus(unsigned int primary_cpu)
{
unsigned int cpu;
int error;
cpu_maps_update_begin();
/*
* Make certain the cpu I'm about to reboot on is online.
*
* This is inline to what migrate_to_reboot_cpu() already do.
*/
if (!cpu_online(primary_cpu))
primary_cpu = cpumask_first(cpu_online_mask);
for_each_online_cpu(cpu) {
if (cpu == primary_cpu)
continue;
error = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
if (error) {
pr_err("Failed to offline CPU%d - error=%d",
cpu, error);
break;
}
}
/*
* Ensure all but the reboot CPU are offline.
*/
BUG_ON(num_online_cpus() > 1);
/*
* Make sure the CPUs won't be enabled by someone else after this
* point. Kexec will reboot to a new kernel shortly resetting
* everything along the way.
*/
cpu_hotplug_disabled++;
cpu_maps_update_done();
}
EXPORT_SYMBOL(cpu_down);
#else
#define takedown_cpu NULL
@ -1124,8 +1185,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
}
/*
* The caller of do_cpu_up might have raced with another
* caller. Ignore it for now.
* The caller of cpu_up() might have raced with another
* caller. Nothing to do.
*/
if (st->state >= target)
goto out;
@ -1169,7 +1230,7 @@ out:
return ret;
}
static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
static int cpu_up(unsigned int cpu, enum cpuhp_state target)
{
int err = 0;
@ -1203,16 +1264,70 @@ out:
return err;
}
int cpu_up(unsigned int cpu)
/**
* cpu_device_up - Bring up a cpu device
* @dev: Pointer to the cpu device to online
*
* This function is meant to be used by device core cpu subsystem only.
*
* Other subsystems should use add_cpu() instead.
*/
int cpu_device_up(struct device *dev)
{
return do_cpu_up(cpu, CPUHP_ONLINE);
return cpu_up(dev->id, CPUHP_ONLINE);
}
int add_cpu(unsigned int cpu)
{
int ret;
lock_device_hotplug();
ret = device_online(get_cpu_device(cpu));
unlock_device_hotplug();
return ret;
}
EXPORT_SYMBOL_GPL(add_cpu);
/**
* bringup_hibernate_cpu - Bring up the CPU that we hibernated on
* @sleep_cpu: The cpu we hibernated on and should be brought up.
*
* On some architectures like arm64, we can hibernate on any CPU, but on
* wake up the CPU we hibernated on might be offline as a side effect of
* using maxcpus= for example.
*/
int bringup_hibernate_cpu(unsigned int sleep_cpu)
{
int ret;
if (!cpu_online(sleep_cpu)) {
pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
ret = cpu_up(sleep_cpu, CPUHP_ONLINE);
if (ret) {
pr_err("Failed to bring hibernate-CPU up!\n");
return ret;
}
}
return 0;
}
void bringup_nonboot_cpus(unsigned int setup_max_cpus)
{
unsigned int cpu;
for_each_present_cpu(cpu) {
if (num_online_cpus() >= setup_max_cpus)
break;
if (!cpu_online(cpu))
cpu_up(cpu, CPUHP_ONLINE);
}
}
EXPORT_SYMBOL_GPL(cpu_up);
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;
int freeze_secondary_cpus(int primary)
int __freeze_secondary_cpus(int primary, bool suspend)
{
int cpu, error = 0;
@ -1237,7 +1352,7 @@ int freeze_secondary_cpus(int primary)
if (cpu == primary)
continue;
if (pm_wakeup_pending()) {
if (suspend && pm_wakeup_pending()) {
pr_info("Wakeup pending. Abort CPU freeze\n");
error = -EBUSY;
break;
@ -2028,9 +2143,9 @@ static ssize_t write_cpuhp_target(struct device *dev,
goto out;
if (st->state < target)
ret = do_cpu_up(dev->id, target);
ret = cpu_up(dev->id, target);
else
ret = do_cpu_down(dev->id, target);
ret = cpu_down(dev->id, target);
out:
unlock_device_hotplug();
return ret ? ret : count;

View File

@ -269,7 +269,6 @@ static void __hrtick_start(void *arg)
rq_lock(rq, &rf);
__hrtick_restart(rq);
rq->hrtick_csd_pending = 0;
rq_unlock(rq, &rf);
}
@ -293,12 +292,10 @@ void hrtick_start(struct rq *rq, u64 delay)
hrtimer_set_expires(timer, time);
if (rq == this_rq()) {
if (rq == this_rq())
__hrtick_restart(rq);
} else if (!rq->hrtick_csd_pending) {
else
smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
rq->hrtick_csd_pending = 1;
}
}
#else
@ -322,8 +319,6 @@ void hrtick_start(struct rq *rq, u64 delay)
static void hrtick_rq_init(struct rq *rq)
{
#ifdef CONFIG_SMP
rq->hrtick_csd_pending = 0;
rq->hrtick_csd.flags = 0;
rq->hrtick_csd.func = __hrtick_start;
rq->hrtick_csd.info = rq;

View File

@ -992,7 +992,6 @@ struct rq {
#ifdef CONFIG_SCHED_HRTICK
#ifdef CONFIG_SMP
int hrtick_csd_pending;
call_single_data_t hrtick_csd;
#endif
struct hrtimer hrtick_timer;

View File

@ -329,6 +329,11 @@ EXPORT_SYMBOL(smp_call_function_single);
* (ie: embedded in an object) and is responsible for synchronizing it
* such that the IPIs performed on the @csd are strictly serialized.
*
* If the function is called with one csd which has not yet been
* processed by previous call to smp_call_function_single_async(), the
* function will return immediately with -EBUSY showing that the csd
* object is still in progress.
*
* NOTE: Be careful, there is unfortunately no current debugging facility to
* validate the correctness of this serialization.
*/
@ -338,14 +343,17 @@ int smp_call_function_single_async(int cpu, call_single_data_t *csd)
preempt_disable();
/* We could deadlock if we have to wait here with interrupts disabled! */
if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
csd_lock_wait(csd);
if (csd->flags & CSD_FLAG_LOCK) {
err = -EBUSY;
goto out;
}
csd->flags = CSD_FLAG_LOCK;
smp_wmb();
err = generic_exec_single(cpu, csd, csd->func, csd->info);
out:
preempt_enable();
return err;
@ -589,20 +597,13 @@ void __init setup_nr_cpu_ids(void)
void __init smp_init(void)
{
int num_nodes, num_cpus;
unsigned int cpu;
idle_threads_init();
cpuhp_threads_init();
pr_info("Bringing up secondary CPUs ...\n");
/* FIXME: This should be done in userspace --RR */
for_each_present_cpu(cpu) {
if (num_online_cpus() >= setup_max_cpus)
break;
if (!cpu_online(cpu))
cpu_up(cpu);
}
bringup_nonboot_cpus(setup_max_cpus);
num_nodes = num_online_nodes();
num_cpus = num_online_cpus();

View File

@ -101,7 +101,7 @@ bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
torture_type, cpu);
starttime = jiffies;
(*n_offl_attempts)++;
ret = cpu_down(cpu);
ret = remove_cpu(cpu);
if (ret) {
s = "";
if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
@ -159,7 +159,7 @@ bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
torture_type, cpu);
starttime = jiffies;
(*n_onl_attempts)++;
ret = cpu_up(cpu);
ret = add_cpu(cpu);
if (ret) {
s = "";
if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
@ -209,17 +209,18 @@ torture_onoff(void *arg)
for_each_online_cpu(cpu)
maxcpu = cpu;
WARN_ON(maxcpu < 0);
if (!IS_MODULE(CONFIG_TORTURE_TEST))
if (!IS_MODULE(CONFIG_TORTURE_TEST)) {
for_each_possible_cpu(cpu) {
if (cpu_online(cpu))
continue;
ret = cpu_up(cpu);
ret = add_cpu(cpu);
if (ret && verbose) {
pr_alert("%s" TORTURE_FLAG
"%s: Initial online %d: errno %d\n",
__func__, torture_type, cpu, ret);
}
}
}
if (maxcpu == 0) {
VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");