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![Linus Torvalds](/assets/img/avatar_default.png)
Pull cpu hotplug updates from Thomas Gleixner: "This is the first part of the ongoing cpu hotplug rework: - Initial implementation of the state machine - Runs all online and prepare down callbacks on the plugged cpu and not on some random processor - Replaces busy loop waiting with completions - Adds tracepoints so the states can be followed" More detailed commentary on this work from an earlier email: "What's wrong with the current cpu hotplug infrastructure? - Asymmetry The hotplug notifier mechanism is asymmetric versus the bringup and teardown. This is mostly caused by the notifier mechanism. - Largely undocumented dependencies While some notifiers use explicitely defined notifier priorities, we have quite some notifiers which use numerical priorities to express dependencies without any documentation why. - Control processor driven Most of the bringup/teardown of a cpu is driven by a control processor. While it is understandable, that preperatory steps, like idle thread creation, memory allocation for and initialization of essential facilities needs to be done before a cpu can boot, there is no reason why everything else must run on a control processor. Before this patch series, bringup looks like this: Control CPU Booting CPU do preparatory steps kick cpu into life do low level init sync with booting cpu sync with control cpu bring the rest up - All or nothing approach There is no way to do partial bringups. That's something which is really desired because we waste e.g. at boot substantial amount of time just busy waiting that the cpu comes to life. That's stupid as we could very well do preparatory steps and the initial IPI for other cpus and then go back and do the necessary low level synchronization with the freshly booted cpu. - Minimal debuggability Due to the notifier based design, it's impossible to switch between two stages of the bringup/teardown back and forth in order to test the correctness. So in many hotplug notifiers the cancel mechanisms are either not existant or completely untested. - Notifier [un]registering is tedious To [un]register notifiers we need to protect against hotplug at every callsite. There is no mechanism that bringup/teardown callbacks are issued on the online cpus, so every caller needs to do it itself. That also includes error rollback. What's the new design? The base of the new design is a symmetric state machine, where both the control processor and the booting/dying cpu execute a well defined set of states. Each state is symmetric in the end, except for some well defined exceptions, and the bringup/teardown can be stopped and reversed at almost all states. So the bringup of a cpu will look like this in the future: Control CPU Booting CPU do preparatory steps kick cpu into life do low level init sync with booting cpu sync with control cpu bring itself up The synchronization step does not require the control cpu to wait. That mechanism can be done asynchronously via a worker or some other mechanism. The teardown can be made very similar, so that the dying cpu cleans up and brings itself down. Cleanups which need to be done after the cpu is gone, can be scheduled asynchronously as well. There is a long way to this, as we need to refactor the notion when a cpu is available. Today we set the cpu online right after it comes out of the low level bringup, which is not really correct. The proper mechanism is to set it to available, i.e. cpu local threads, like softirqd, hotplug thread etc. can be scheduled on that cpu, and once it finished all booting steps, it's set to online, so general workloads can be scheduled on it. The reverse happens on teardown. First thing to do is to forbid scheduling of general workloads, then teardown all the per cpu resources and finally shut it off completely. This patch series implements the basic infrastructure for this at the core level. This includes the following: - Basic state machine implementation with well defined states, so ordering and prioritization can be expressed. - Interfaces to [un]register state callbacks This invokes the bringup/teardown callback on all online cpus with the proper protection in place and [un]installs the callbacks in the state machine array. For callbacks which have no particular ordering requirement we have a dynamic state space, so that drivers don't have to register an explicit hotplug state. If a callback fails, the code automatically does a rollback to the previous state. - Sysfs interface to drive the state machine to a particular step. This is only partially functional today. Full functionality and therefor testability will be achieved once we converted all existing hotplug notifiers over to the new scheme. - Run all CPU_ONLINE/DOWN_PREPARE notifiers on the booting/dying processor: Control CPU Booting CPU do preparatory steps kick cpu into life do low level init sync with booting cpu sync with control cpu wait for boot bring itself up Signal completion to control cpu In a previous step of this work we've done a full tree mechanical conversion of all hotplug notifiers to the new scheme. The balance is a net removal of about 4000 lines of code. This is not included in this series, as we decided to take a different approach. Instead of mechanically converting everything over, we will do a proper overhaul of the usage sites one by one so they nicely fit into the symmetric callback scheme. I decided to do that after I looked at the ugliness of some of the converted sites and figured out that their hotplug mechanism is completely buggered anyway. So there is no point to do a mechanical conversion first as we need to go through the usage sites one by one again in order to achieve a full symmetric and testable behaviour" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits) cpu/hotplug: Document states better cpu/hotplug: Fix smpboot thread ordering cpu/hotplug: Remove redundant state check cpu/hotplug: Plug death reporting race rcu: Make CPU_DYING_IDLE an explicit call cpu/hotplug: Make wait for dead cpu completion based cpu/hotplug: Let upcoming cpu bring itself fully up arch/hotplug: Call into idle with a proper state cpu/hotplug: Move online calls to hotplugged cpu cpu/hotplug: Create hotplug threads cpu/hotplug: Split out the state walk into functions cpu/hotplug: Unpark smpboot threads from the state machine cpu/hotplug: Move scheduler cpu_online notifier to hotplug core cpu/hotplug: Implement setup/removal interface cpu/hotplug: Make target state writeable cpu/hotplug: Add sysfs state interface cpu/hotplug: Hand in target state to _cpu_up/down cpu/hotplug: Convert the hotplugged cpu work to a state machine cpu/hotplug: Convert to a state machine for the control processor cpu/hotplug: Add tracepoints ...
741 lines
20 KiB
C
741 lines
20 KiB
C
/*
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* Generic helpers for smp ipi calls
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*
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* (C) Jens Axboe <jens.axboe@oracle.com> 2008
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*/
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#include <linux/irq_work.h>
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#include <linux/rcupdate.h>
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#include <linux/rculist.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/gfp.h>
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#include <linux/smp.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include "smpboot.h"
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enum {
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CSD_FLAG_LOCK = 0x01,
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CSD_FLAG_SYNCHRONOUS = 0x02,
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};
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struct call_function_data {
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struct call_single_data __percpu *csd;
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cpumask_var_t cpumask;
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};
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
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static void flush_smp_call_function_queue(bool warn_cpu_offline);
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static int
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hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
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{
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long cpu = (long)hcpu;
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struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
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switch (action) {
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case CPU_UP_PREPARE:
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case CPU_UP_PREPARE_FROZEN:
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if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
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cpu_to_node(cpu)))
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return notifier_from_errno(-ENOMEM);
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cfd->csd = alloc_percpu(struct call_single_data);
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if (!cfd->csd) {
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free_cpumask_var(cfd->cpumask);
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return notifier_from_errno(-ENOMEM);
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}
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break;
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#ifdef CONFIG_HOTPLUG_CPU
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case CPU_UP_CANCELED:
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case CPU_UP_CANCELED_FROZEN:
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/* Fall-through to the CPU_DEAD[_FROZEN] case. */
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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free_cpumask_var(cfd->cpumask);
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free_percpu(cfd->csd);
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break;
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case CPU_DYING:
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case CPU_DYING_FROZEN:
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/*
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* The IPIs for the smp-call-function callbacks queued by other
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* CPUs might arrive late, either due to hardware latencies or
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* because this CPU disabled interrupts (inside stop-machine)
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* before the IPIs were sent. So flush out any pending callbacks
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* explicitly (without waiting for the IPIs to arrive), to
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* ensure that the outgoing CPU doesn't go offline with work
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* still pending.
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*/
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flush_smp_call_function_queue(false);
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break;
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#endif
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};
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return NOTIFY_OK;
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}
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static struct notifier_block hotplug_cfd_notifier = {
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.notifier_call = hotplug_cfd,
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};
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void __init call_function_init(void)
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{
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void *cpu = (void *)(long)smp_processor_id();
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int i;
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for_each_possible_cpu(i)
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init_llist_head(&per_cpu(call_single_queue, i));
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hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
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register_cpu_notifier(&hotplug_cfd_notifier);
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}
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/*
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* csd_lock/csd_unlock used to serialize access to per-cpu csd resources
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*
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* For non-synchronous ipi calls the csd can still be in use by the
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* previous function call. For multi-cpu calls its even more interesting
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* as we'll have to ensure no other cpu is observing our csd.
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*/
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static __always_inline void csd_lock_wait(struct call_single_data *csd)
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{
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smp_cond_acquire(!(csd->flags & CSD_FLAG_LOCK));
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}
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static __always_inline void csd_lock(struct call_single_data *csd)
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{
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csd_lock_wait(csd);
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csd->flags |= CSD_FLAG_LOCK;
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/*
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* prevent CPU from reordering the above assignment
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* to ->flags with any subsequent assignments to other
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* fields of the specified call_single_data structure:
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*/
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smp_wmb();
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}
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static __always_inline void csd_unlock(struct call_single_data *csd)
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{
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WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
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/*
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* ensure we're all done before releasing data:
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*/
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smp_store_release(&csd->flags, 0);
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}
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
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/*
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* Insert a previously allocated call_single_data element
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* for execution on the given CPU. data must already have
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* ->func, ->info, and ->flags set.
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*/
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static int generic_exec_single(int cpu, struct call_single_data *csd,
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smp_call_func_t func, void *info)
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{
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if (cpu == smp_processor_id()) {
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unsigned long flags;
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/*
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* We can unlock early even for the synchronous on-stack case,
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* since we're doing this from the same CPU..
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*/
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csd_unlock(csd);
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local_irq_save(flags);
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func(info);
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local_irq_restore(flags);
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return 0;
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}
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if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
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csd_unlock(csd);
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return -ENXIO;
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}
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csd->func = func;
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csd->info = info;
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/*
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* The list addition should be visible before sending the IPI
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* handler locks the list to pull the entry off it because of
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* normal cache coherency rules implied by spinlocks.
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*
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* If IPIs can go out of order to the cache coherency protocol
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* in an architecture, sufficient synchronisation should be added
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* to arch code to make it appear to obey cache coherency WRT
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* locking and barrier primitives. Generic code isn't really
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* equipped to do the right thing...
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*/
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if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
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arch_send_call_function_single_ipi(cpu);
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return 0;
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}
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/**
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* generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
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*
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* Invoked by arch to handle an IPI for call function single.
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* Must be called with interrupts disabled.
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*/
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void generic_smp_call_function_single_interrupt(void)
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{
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flush_smp_call_function_queue(true);
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}
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/**
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* flush_smp_call_function_queue - Flush pending smp-call-function callbacks
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*
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* @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
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* offline CPU. Skip this check if set to 'false'.
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*
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* Flush any pending smp-call-function callbacks queued on this CPU. This is
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* invoked by the generic IPI handler, as well as by a CPU about to go offline,
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* to ensure that all pending IPI callbacks are run before it goes completely
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* offline.
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*
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* Loop through the call_single_queue and run all the queued callbacks.
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* Must be called with interrupts disabled.
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*/
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static void flush_smp_call_function_queue(bool warn_cpu_offline)
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{
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struct llist_head *head;
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struct llist_node *entry;
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struct call_single_data *csd, *csd_next;
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static bool warned;
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WARN_ON(!irqs_disabled());
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head = this_cpu_ptr(&call_single_queue);
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entry = llist_del_all(head);
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entry = llist_reverse_order(entry);
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/* There shouldn't be any pending callbacks on an offline CPU. */
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if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
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!warned && !llist_empty(head))) {
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warned = true;
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WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
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/*
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* We don't have to use the _safe() variant here
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* because we are not invoking the IPI handlers yet.
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*/
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llist_for_each_entry(csd, entry, llist)
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pr_warn("IPI callback %pS sent to offline CPU\n",
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csd->func);
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}
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llist_for_each_entry_safe(csd, csd_next, entry, llist) {
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smp_call_func_t func = csd->func;
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void *info = csd->info;
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/* Do we wait until *after* callback? */
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if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
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func(info);
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csd_unlock(csd);
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} else {
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csd_unlock(csd);
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func(info);
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}
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}
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/*
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* Handle irq works queued remotely by irq_work_queue_on().
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* Smp functions above are typically synchronous so they
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* better run first since some other CPUs may be busy waiting
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* for them.
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*/
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irq_work_run();
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}
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/*
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* smp_call_function_single - Run a function on a specific CPU
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait until function has completed on other CPUs.
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*
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* Returns 0 on success, else a negative status code.
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*/
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int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
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int wait)
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{
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struct call_single_data *csd;
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struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS };
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int this_cpu;
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int err;
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/*
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* prevent preemption and reschedule on another processor,
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* as well as CPU removal
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*/
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this_cpu = get_cpu();
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/*
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* Can deadlock when called with interrupts disabled.
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* We allow cpu's that are not yet online though, as no one else can
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* send smp call function interrupt to this cpu and as such deadlocks
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* can't happen.
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*/
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WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
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&& !oops_in_progress);
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csd = &csd_stack;
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if (!wait) {
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csd = this_cpu_ptr(&csd_data);
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csd_lock(csd);
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}
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err = generic_exec_single(cpu, csd, func, info);
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if (wait)
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csd_lock_wait(csd);
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put_cpu();
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return err;
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}
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EXPORT_SYMBOL(smp_call_function_single);
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/**
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* smp_call_function_single_async(): Run an asynchronous function on a
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* specific CPU.
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* @cpu: The CPU to run on.
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* @csd: Pre-allocated and setup data structure
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*
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* Like smp_call_function_single(), but the call is asynchonous and
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* can thus be done from contexts with disabled interrupts.
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*
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* The caller passes his own pre-allocated data structure
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* (ie: embedded in an object) and is responsible for synchronizing it
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* such that the IPIs performed on the @csd are strictly serialized.
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*
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* NOTE: Be careful, there is unfortunately no current debugging facility to
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* validate the correctness of this serialization.
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*/
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int smp_call_function_single_async(int cpu, struct call_single_data *csd)
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{
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int err = 0;
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preempt_disable();
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/* We could deadlock if we have to wait here with interrupts disabled! */
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if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
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csd_lock_wait(csd);
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csd->flags = CSD_FLAG_LOCK;
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smp_wmb();
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err = generic_exec_single(cpu, csd, csd->func, csd->info);
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preempt_enable();
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return err;
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}
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EXPORT_SYMBOL_GPL(smp_call_function_single_async);
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/*
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* smp_call_function_any - Run a function on any of the given cpus
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* @mask: The mask of cpus it can run on.
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait until function has completed.
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*
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* Returns 0 on success, else a negative status code (if no cpus were online).
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*
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* Selection preference:
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* 1) current cpu if in @mask
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* 2) any cpu of current node if in @mask
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* 3) any other online cpu in @mask
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*/
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int smp_call_function_any(const struct cpumask *mask,
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smp_call_func_t func, void *info, int wait)
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{
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unsigned int cpu;
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const struct cpumask *nodemask;
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int ret;
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/* Try for same CPU (cheapest) */
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cpu = get_cpu();
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if (cpumask_test_cpu(cpu, mask))
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goto call;
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/* Try for same node. */
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nodemask = cpumask_of_node(cpu_to_node(cpu));
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for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
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cpu = cpumask_next_and(cpu, nodemask, mask)) {
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if (cpu_online(cpu))
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goto call;
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}
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/* Any online will do: smp_call_function_single handles nr_cpu_ids. */
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cpu = cpumask_any_and(mask, cpu_online_mask);
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call:
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ret = smp_call_function_single(cpu, func, info, wait);
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put_cpu();
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return ret;
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}
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EXPORT_SYMBOL_GPL(smp_call_function_any);
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/**
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* smp_call_function_many(): Run a function on a set of other CPUs.
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* @mask: The set of cpus to run on (only runs on online subset).
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait (atomically) until function has completed
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* on other CPUs.
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*
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* If @wait is true, then returns once @func has returned.
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*
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* You must not call this function with disabled interrupts or from a
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* hardware interrupt handler or from a bottom half handler. Preemption
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* must be disabled when calling this function.
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*/
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void smp_call_function_many(const struct cpumask *mask,
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smp_call_func_t func, void *info, bool wait)
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{
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struct call_function_data *cfd;
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int cpu, next_cpu, this_cpu = smp_processor_id();
|
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|
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/*
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* Can deadlock when called with interrupts disabled.
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* We allow cpu's that are not yet online though, as no one else can
|
|
* send smp call function interrupt to this cpu and as such deadlocks
|
|
* can't happen.
|
|
*/
|
|
WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
|
&& !oops_in_progress && !early_boot_irqs_disabled);
|
|
|
|
/* Try to fastpath. So, what's a CPU they want? Ignoring this one. */
|
|
cpu = cpumask_first_and(mask, cpu_online_mask);
|
|
if (cpu == this_cpu)
|
|
cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
|
|
|
/* No online cpus? We're done. */
|
|
if (cpu >= nr_cpu_ids)
|
|
return;
|
|
|
|
/* Do we have another CPU which isn't us? */
|
|
next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
|
if (next_cpu == this_cpu)
|
|
next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
|
|
|
|
/* Fastpath: do that cpu by itself. */
|
|
if (next_cpu >= nr_cpu_ids) {
|
|
smp_call_function_single(cpu, func, info, wait);
|
|
return;
|
|
}
|
|
|
|
cfd = this_cpu_ptr(&cfd_data);
|
|
|
|
cpumask_and(cfd->cpumask, mask, cpu_online_mask);
|
|
cpumask_clear_cpu(this_cpu, cfd->cpumask);
|
|
|
|
/* Some callers race with other cpus changing the passed mask */
|
|
if (unlikely(!cpumask_weight(cfd->cpumask)))
|
|
return;
|
|
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu);
|
|
|
|
csd_lock(csd);
|
|
if (wait)
|
|
csd->flags |= CSD_FLAG_SYNCHRONOUS;
|
|
csd->func = func;
|
|
csd->info = info;
|
|
llist_add(&csd->llist, &per_cpu(call_single_queue, cpu));
|
|
}
|
|
|
|
/* Send a message to all CPUs in the map */
|
|
arch_send_call_function_ipi_mask(cfd->cpumask);
|
|
|
|
if (wait) {
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
struct call_single_data *csd;
|
|
|
|
csd = per_cpu_ptr(cfd->csd, cpu);
|
|
csd_lock_wait(csd);
|
|
}
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function_many);
|
|
|
|
/**
|
|
* smp_call_function(): Run a function on all other CPUs.
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: If true, wait (atomically) until function has completed
|
|
* on other CPUs.
|
|
*
|
|
* Returns 0.
|
|
*
|
|
* If @wait is true, then returns once @func has returned; otherwise
|
|
* it returns just before the target cpu calls @func.
|
|
*
|
|
* You must not call this function with disabled interrupts or from a
|
|
* hardware interrupt handler or from a bottom half handler.
|
|
*/
|
|
int smp_call_function(smp_call_func_t func, void *info, int wait)
|
|
{
|
|
preempt_disable();
|
|
smp_call_function_many(cpu_online_mask, func, info, wait);
|
|
preempt_enable();
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function);
|
|
|
|
/* Setup configured maximum number of CPUs to activate */
|
|
unsigned int setup_max_cpus = NR_CPUS;
|
|
EXPORT_SYMBOL(setup_max_cpus);
|
|
|
|
|
|
/*
|
|
* Setup routine for controlling SMP activation
|
|
*
|
|
* Command-line option of "nosmp" or "maxcpus=0" will disable SMP
|
|
* activation entirely (the MPS table probe still happens, though).
|
|
*
|
|
* Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
|
|
* greater than 0, limits the maximum number of CPUs activated in
|
|
* SMP mode to <NUM>.
|
|
*/
|
|
|
|
void __weak arch_disable_smp_support(void) { }
|
|
|
|
static int __init nosmp(char *str)
|
|
{
|
|
setup_max_cpus = 0;
|
|
arch_disable_smp_support();
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("nosmp", nosmp);
|
|
|
|
/* this is hard limit */
|
|
static int __init nrcpus(char *str)
|
|
{
|
|
int nr_cpus;
|
|
|
|
get_option(&str, &nr_cpus);
|
|
if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
|
|
nr_cpu_ids = nr_cpus;
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("nr_cpus", nrcpus);
|
|
|
|
static int __init maxcpus(char *str)
|
|
{
|
|
get_option(&str, &setup_max_cpus);
|
|
if (setup_max_cpus == 0)
|
|
arch_disable_smp_support();
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("maxcpus", maxcpus);
|
|
|
|
/* Setup number of possible processor ids */
|
|
int nr_cpu_ids __read_mostly = NR_CPUS;
|
|
EXPORT_SYMBOL(nr_cpu_ids);
|
|
|
|
/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
|
|
void __init setup_nr_cpu_ids(void)
|
|
{
|
|
nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
|
|
}
|
|
|
|
void __weak smp_announce(void)
|
|
{
|
|
printk(KERN_INFO "Brought up %d CPUs\n", num_online_cpus());
|
|
}
|
|
|
|
/* Called by boot processor to activate the rest. */
|
|
void __init smp_init(void)
|
|
{
|
|
unsigned int cpu;
|
|
|
|
idle_threads_init();
|
|
cpuhp_threads_init();
|
|
|
|
/* 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);
|
|
}
|
|
|
|
/* Any cleanup work */
|
|
smp_announce();
|
|
smp_cpus_done(setup_max_cpus);
|
|
}
|
|
|
|
/*
|
|
* Call a function on all processors. May be used during early boot while
|
|
* early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
|
|
* of local_irq_disable/enable().
|
|
*/
|
|
int on_each_cpu(void (*func) (void *info), void *info, int wait)
|
|
{
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
preempt_disable();
|
|
ret = smp_call_function(func, info, wait);
|
|
local_irq_save(flags);
|
|
func(info);
|
|
local_irq_restore(flags);
|
|
preempt_enable();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(on_each_cpu);
|
|
|
|
/**
|
|
* on_each_cpu_mask(): Run a function on processors specified by
|
|
* cpumask, which may include the local processor.
|
|
* @mask: The set of cpus to run on (only runs on online subset).
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: If true, wait (atomically) until function has completed
|
|
* on other CPUs.
|
|
*
|
|
* If @wait is true, then returns once @func has returned.
|
|
*
|
|
* You must not call this function with disabled interrupts or from a
|
|
* hardware interrupt handler or from a bottom half handler. The
|
|
* exception is that it may be used during early boot while
|
|
* early_boot_irqs_disabled is set.
|
|
*/
|
|
void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
|
|
void *info, bool wait)
|
|
{
|
|
int cpu = get_cpu();
|
|
|
|
smp_call_function_many(mask, func, info, wait);
|
|
if (cpumask_test_cpu(cpu, mask)) {
|
|
unsigned long flags;
|
|
local_irq_save(flags);
|
|
func(info);
|
|
local_irq_restore(flags);
|
|
}
|
|
put_cpu();
|
|
}
|
|
EXPORT_SYMBOL(on_each_cpu_mask);
|
|
|
|
/*
|
|
* on_each_cpu_cond(): Call a function on each processor for which
|
|
* the supplied function cond_func returns true, optionally waiting
|
|
* for all the required CPUs to finish. This may include the local
|
|
* processor.
|
|
* @cond_func: A callback function that is passed a cpu id and
|
|
* the the info parameter. The function is called
|
|
* with preemption disabled. The function should
|
|
* return a blooean value indicating whether to IPI
|
|
* the specified CPU.
|
|
* @func: The function to run on all applicable CPUs.
|
|
* This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to both functions.
|
|
* @wait: If true, wait (atomically) until function has
|
|
* completed on other CPUs.
|
|
* @gfp_flags: GFP flags to use when allocating the cpumask
|
|
* used internally by the function.
|
|
*
|
|
* The function might sleep if the GFP flags indicates a non
|
|
* atomic allocation is allowed.
|
|
*
|
|
* Preemption is disabled to protect against CPUs going offline but not online.
|
|
* CPUs going online during the call will not be seen or sent an IPI.
|
|
*
|
|
* You must not call this function with disabled interrupts or
|
|
* from a hardware interrupt handler or from a bottom half handler.
|
|
*/
|
|
void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
|
|
smp_call_func_t func, void *info, bool wait,
|
|
gfp_t gfp_flags)
|
|
{
|
|
cpumask_var_t cpus;
|
|
int cpu, ret;
|
|
|
|
might_sleep_if(gfpflags_allow_blocking(gfp_flags));
|
|
|
|
if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
|
|
preempt_disable();
|
|
for_each_online_cpu(cpu)
|
|
if (cond_func(cpu, info))
|
|
cpumask_set_cpu(cpu, cpus);
|
|
on_each_cpu_mask(cpus, func, info, wait);
|
|
preempt_enable();
|
|
free_cpumask_var(cpus);
|
|
} else {
|
|
/*
|
|
* No free cpumask, bother. No matter, we'll
|
|
* just have to IPI them one by one.
|
|
*/
|
|
preempt_disable();
|
|
for_each_online_cpu(cpu)
|
|
if (cond_func(cpu, info)) {
|
|
ret = smp_call_function_single(cpu, func,
|
|
info, wait);
|
|
WARN_ON_ONCE(ret);
|
|
}
|
|
preempt_enable();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(on_each_cpu_cond);
|
|
|
|
static void do_nothing(void *unused)
|
|
{
|
|
}
|
|
|
|
/**
|
|
* kick_all_cpus_sync - Force all cpus out of idle
|
|
*
|
|
* Used to synchronize the update of pm_idle function pointer. It's
|
|
* called after the pointer is updated and returns after the dummy
|
|
* callback function has been executed on all cpus. The execution of
|
|
* the function can only happen on the remote cpus after they have
|
|
* left the idle function which had been called via pm_idle function
|
|
* pointer. So it's guaranteed that nothing uses the previous pointer
|
|
* anymore.
|
|
*/
|
|
void kick_all_cpus_sync(void)
|
|
{
|
|
/* Make sure the change is visible before we kick the cpus */
|
|
smp_mb();
|
|
smp_call_function(do_nothing, NULL, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
|
|
|
|
/**
|
|
* wake_up_all_idle_cpus - break all cpus out of idle
|
|
* wake_up_all_idle_cpus try to break all cpus which is in idle state even
|
|
* including idle polling cpus, for non-idle cpus, we will do nothing
|
|
* for them.
|
|
*/
|
|
void wake_up_all_idle_cpus(void)
|
|
{
|
|
int cpu;
|
|
|
|
preempt_disable();
|
|
for_each_online_cpu(cpu) {
|
|
if (cpu == smp_processor_id())
|
|
continue;
|
|
|
|
wake_up_if_idle(cpu);
|
|
}
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
|