| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Generic helpers for smp ipi calls |
| * |
| * (C) Jens Axboe <jens.axboe@oracle.com> 2008 |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/irq_work.h> |
| #include <linux/rcupdate.h> |
| #include <linux/rculist.h> |
| #include <linux/kernel.h> |
| #include <linux/export.h> |
| #include <linux/percpu.h> |
| #include <linux/init.h> |
| #include <linux/interrupt.h> |
| #include <linux/gfp.h> |
| #include <linux/smp.h> |
| #include <linux/cpu.h> |
| #include <linux/sched.h> |
| #include <linux/sched/idle.h> |
| #include <linux/hypervisor.h> |
| #include <linux/sched/clock.h> |
| #include <linux/nmi.h> |
| #include <linux/sched/debug.h> |
| |
| #include "smpboot.h" |
| #include "sched/smp.h" |
| |
| #define CSD_TYPE(_csd) ((_csd)->flags & CSD_FLAG_TYPE_MASK) |
| |
| struct call_function_data { |
| call_single_data_t __percpu *csd; |
| cpumask_var_t cpumask; |
| cpumask_var_t cpumask_ipi; |
| }; |
| |
| static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data); |
| |
| static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); |
| |
| static void flush_smp_call_function_queue(bool warn_cpu_offline); |
| |
| int smpcfd_prepare_cpu(unsigned int cpu) |
| { |
| struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
| |
| if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, |
| cpu_to_node(cpu))) |
| return -ENOMEM; |
| if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL, |
| cpu_to_node(cpu))) { |
| free_cpumask_var(cfd->cpumask); |
| return -ENOMEM; |
| } |
| cfd->csd = alloc_percpu(call_single_data_t); |
| if (!cfd->csd) { |
| free_cpumask_var(cfd->cpumask); |
| free_cpumask_var(cfd->cpumask_ipi); |
| return -ENOMEM; |
| } |
| |
| return 0; |
| } |
| |
| int smpcfd_dead_cpu(unsigned int cpu) |
| { |
| struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
| |
| free_cpumask_var(cfd->cpumask); |
| free_cpumask_var(cfd->cpumask_ipi); |
| free_percpu(cfd->csd); |
| return 0; |
| } |
| |
| int smpcfd_dying_cpu(unsigned int cpu) |
| { |
| /* |
| * The IPIs for the smp-call-function callbacks queued by other |
| * CPUs might arrive late, either due to hardware latencies or |
| * because this CPU disabled interrupts (inside stop-machine) |
| * before the IPIs were sent. So flush out any pending callbacks |
| * explicitly (without waiting for the IPIs to arrive), to |
| * ensure that the outgoing CPU doesn't go offline with work |
| * still pending. |
| */ |
| flush_smp_call_function_queue(false); |
| irq_work_run(); |
| return 0; |
| } |
| |
| void __init call_function_init(void) |
| { |
| int i; |
| |
| for_each_possible_cpu(i) |
| init_llist_head(&per_cpu(call_single_queue, i)); |
| |
| smpcfd_prepare_cpu(smp_processor_id()); |
| } |
| |
| #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
| |
| static DEFINE_PER_CPU(call_single_data_t *, cur_csd); |
| static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func); |
| static DEFINE_PER_CPU(void *, cur_csd_info); |
| |
| #define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC) |
| static atomic_t csd_bug_count = ATOMIC_INIT(0); |
| |
| /* Record current CSD work for current CPU, NULL to erase. */ |
| static void csd_lock_record(struct __call_single_data *csd) |
| { |
| if (!csd) { |
| smp_mb(); /* NULL cur_csd after unlock. */ |
| __this_cpu_write(cur_csd, NULL); |
| return; |
| } |
| __this_cpu_write(cur_csd_func, csd->func); |
| __this_cpu_write(cur_csd_info, csd->info); |
| smp_wmb(); /* func and info before csd. */ |
| __this_cpu_write(cur_csd, csd); |
| smp_mb(); /* Update cur_csd before function call. */ |
| /* Or before unlock, as the case may be. */ |
| } |
| |
| static __always_inline int csd_lock_wait_getcpu(struct __call_single_data *csd) |
| { |
| unsigned int csd_type; |
| |
| csd_type = CSD_TYPE(csd); |
| if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC) |
| return csd->dst; /* Other CSD_TYPE_ values might not have ->dst. */ |
| return -1; |
| } |
| |
| /* |
| * Complain if too much time spent waiting. Note that only |
| * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU, |
| * so waiting on other types gets much less information. |
| */ |
| static __always_inline bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *ts1, int *bug_id) |
| { |
| int cpu = -1; |
| int cpux; |
| bool firsttime; |
| u64 ts2, ts_delta; |
| call_single_data_t *cpu_cur_csd; |
| unsigned int flags = READ_ONCE(csd->flags); |
| |
| if (!(flags & CSD_FLAG_LOCK)) { |
| if (!unlikely(*bug_id)) |
| return true; |
| cpu = csd_lock_wait_getcpu(csd); |
| pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n", |
| *bug_id, raw_smp_processor_id(), cpu); |
| return true; |
| } |
| |
| ts2 = sched_clock(); |
| ts_delta = ts2 - *ts1; |
| if (likely(ts_delta <= CSD_LOCK_TIMEOUT)) |
| return false; |
| |
| firsttime = !*bug_id; |
| if (firsttime) |
| *bug_id = atomic_inc_return(&csd_bug_count); |
| cpu = csd_lock_wait_getcpu(csd); |
| if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu)) |
| cpux = 0; |
| else |
| cpux = cpu; |
| cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */ |
| pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n", |
| firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0, |
| cpu, csd->func, csd->info); |
| if (cpu_cur_csd && csd != cpu_cur_csd) { |
| pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n", |
| *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)), |
| READ_ONCE(per_cpu(cur_csd_info, cpux))); |
| } else { |
| pr_alert("\tcsd: CSD lock (#%d) %s.\n", |
| *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request"); |
| } |
| if (cpu >= 0) { |
| if (!trigger_single_cpu_backtrace(cpu)) |
| dump_cpu_task(cpu); |
| if (!cpu_cur_csd) { |
| pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu); |
| arch_send_call_function_single_ipi(cpu); |
| } |
| } |
| dump_stack(); |
| *ts1 = ts2; |
| |
| return false; |
| } |
| |
| /* |
| * csd_lock/csd_unlock used to serialize access to per-cpu csd resources |
| * |
| * For non-synchronous ipi calls the csd can still be in use by the |
| * previous function call. For multi-cpu calls its even more interesting |
| * as we'll have to ensure no other cpu is observing our csd. |
| */ |
| static __always_inline void csd_lock_wait(struct __call_single_data *csd) |
| { |
| int bug_id = 0; |
| u64 ts0, ts1; |
| |
| ts1 = ts0 = sched_clock(); |
| for (;;) { |
| if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id)) |
| break; |
| cpu_relax(); |
| } |
| smp_acquire__after_ctrl_dep(); |
| } |
| |
| #else |
| static void csd_lock_record(struct __call_single_data *csd) |
| { |
| } |
| |
| static __always_inline void csd_lock_wait(struct __call_single_data *csd) |
| { |
| smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK)); |
| } |
| #endif |
| |
| static __always_inline void csd_lock(struct __call_single_data *csd) |
| { |
| csd_lock_wait(csd); |
| csd->flags |= CSD_FLAG_LOCK; |
| |
| /* |
| * prevent CPU from reordering the above assignment |
| * to ->flags with any subsequent assignments to other |
| * fields of the specified call_single_data_t structure: |
| */ |
| smp_wmb(); |
| } |
| |
| static __always_inline void csd_unlock(struct __call_single_data *csd) |
| { |
| WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); |
| |
| /* |
| * ensure we're all done before releasing data: |
| */ |
| smp_store_release(&csd->flags, 0); |
| } |
| |
| static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data); |
| |
| void __smp_call_single_queue(int cpu, struct llist_node *node) |
| { |
| /* |
| * The list addition should be visible before sending the IPI |
| * handler locks the list to pull the entry off it because of |
| * normal cache coherency rules implied by spinlocks. |
| * |
| * If IPIs can go out of order to the cache coherency protocol |
| * in an architecture, sufficient synchronisation should be added |
| * to arch code to make it appear to obey cache coherency WRT |
| * locking and barrier primitives. Generic code isn't really |
| * equipped to do the right thing... |
| */ |
| if (llist_add(node, &per_cpu(call_single_queue, cpu))) |
| send_call_function_single_ipi(cpu); |
| } |
| |
| /* |
| * Insert a previously allocated call_single_data_t element |
| * for execution on the given CPU. data must already have |
| * ->func, ->info, and ->flags set. |
| */ |
| static int generic_exec_single(int cpu, struct __call_single_data *csd) |
| { |
| if (cpu == smp_processor_id()) { |
| smp_call_func_t func = csd->func; |
| void *info = csd->info; |
| unsigned long flags; |
| |
| /* |
| * We can unlock early even for the synchronous on-stack case, |
| * since we're doing this from the same CPU.. |
| */ |
| csd_lock_record(csd); |
| csd_unlock(csd); |
| local_irq_save(flags); |
| func(info); |
| csd_lock_record(NULL); |
| local_irq_restore(flags); |
| return 0; |
| } |
| |
| if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { |
| csd_unlock(csd); |
| return -ENXIO; |
| } |
| |
| __smp_call_single_queue(cpu, &csd->llist); |
| |
| return 0; |
| } |
| |
| /** |
| * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks |
| * |
| * Invoked by arch to handle an IPI for call function single. |
| * Must be called with interrupts disabled. |
| */ |
| void generic_smp_call_function_single_interrupt(void) |
| { |
| flush_smp_call_function_queue(true); |
| } |
| |
| /** |
| * flush_smp_call_function_queue - Flush pending smp-call-function callbacks |
| * |
| * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an |
| * offline CPU. Skip this check if set to 'false'. |
| * |
| * Flush any pending smp-call-function callbacks queued on this CPU. This is |
| * invoked by the generic IPI handler, as well as by a CPU about to go offline, |
| * to ensure that all pending IPI callbacks are run before it goes completely |
| * offline. |
| * |
| * Loop through the call_single_queue and run all the queued callbacks. |
| * Must be called with interrupts disabled. |
| */ |
| static void flush_smp_call_function_queue(bool warn_cpu_offline) |
| { |
| call_single_data_t *csd, *csd_next; |
| struct llist_node *entry, *prev; |
| struct llist_head *head; |
| static bool warned; |
| |
| lockdep_assert_irqs_disabled(); |
| |
| head = this_cpu_ptr(&call_single_queue); |
| entry = llist_del_all(head); |
| entry = llist_reverse_order(entry); |
| |
| /* There shouldn't be any pending callbacks on an offline CPU. */ |
| if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && |
| !warned && !llist_empty(head))) { |
| warned = true; |
| WARN(1, "IPI on offline CPU %d\n", smp_processor_id()); |
| |
| /* |
| * We don't have to use the _safe() variant here |
| * because we are not invoking the IPI handlers yet. |
| */ |
| llist_for_each_entry(csd, entry, llist) { |
| switch (CSD_TYPE(csd)) { |
| case CSD_TYPE_ASYNC: |
| case CSD_TYPE_SYNC: |
| case CSD_TYPE_IRQ_WORK: |
| pr_warn("IPI callback %pS sent to offline CPU\n", |
| csd->func); |
| break; |
| |
| case CSD_TYPE_TTWU: |
| pr_warn("IPI task-wakeup sent to offline CPU\n"); |
| break; |
| |
| default: |
| pr_warn("IPI callback, unknown type %d, sent to offline CPU\n", |
| CSD_TYPE(csd)); |
| break; |
| } |
| } |
| } |
| |
| /* |
| * First; run all SYNC callbacks, people are waiting for us. |
| */ |
| prev = NULL; |
| llist_for_each_entry_safe(csd, csd_next, entry, llist) { |
| /* Do we wait until *after* callback? */ |
| if (CSD_TYPE(csd) == CSD_TYPE_SYNC) { |
| smp_call_func_t func = csd->func; |
| void *info = csd->info; |
| |
| if (prev) { |
| prev->next = &csd_next->llist; |
| } else { |
| entry = &csd_next->llist; |
| } |
| |
| csd_lock_record(csd); |
| func(info); |
| csd_unlock(csd); |
| csd_lock_record(NULL); |
| } else { |
| prev = &csd->llist; |
| } |
| } |
| |
| if (!entry) |
| return; |
| |
| /* |
| * Second; run all !SYNC callbacks. |
| */ |
| prev = NULL; |
| llist_for_each_entry_safe(csd, csd_next, entry, llist) { |
| int type = CSD_TYPE(csd); |
| |
| if (type != CSD_TYPE_TTWU) { |
| if (prev) { |
| prev->next = &csd_next->llist; |
| } else { |
| entry = &csd_next->llist; |
| } |
| |
| if (type == CSD_TYPE_ASYNC) { |
| smp_call_func_t func = csd->func; |
| void *info = csd->info; |
| |
| csd_lock_record(csd); |
| csd_unlock(csd); |
| func(info); |
| csd_lock_record(NULL); |
| } else if (type == CSD_TYPE_IRQ_WORK) { |
| irq_work_single(csd); |
| } |
| |
| } else { |
| prev = &csd->llist; |
| } |
| } |
| |
| /* |
| * Third; only CSD_TYPE_TTWU is left, issue those. |
| */ |
| if (entry) |
| sched_ttwu_pending(entry); |
| } |
| |
| void flush_smp_call_function_from_idle(void) |
| { |
| unsigned long flags; |
| |
| if (llist_empty(this_cpu_ptr(&call_single_queue))) |
| return; |
| |
| local_irq_save(flags); |
| flush_smp_call_function_queue(true); |
| if (local_softirq_pending()) |
| do_softirq(); |
| |
| local_irq_restore(flags); |
| } |
| |
| /* |
| * smp_call_function_single - Run a function on a specific CPU |
| * @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 until function has completed on other CPUs. |
| * |
| * Returns 0 on success, else a negative status code. |
| */ |
| int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
| int wait) |
| { |
| call_single_data_t *csd; |
| call_single_data_t csd_stack = { |
| .flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, |
| }; |
| int this_cpu; |
| int err; |
| |
| /* |
| * prevent preemption and reschedule on another processor, |
| * as well as CPU removal |
| */ |
| this_cpu = get_cpu(); |
| |
| /* |
| * Can deadlock when called with interrupts disabled. |
| * 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); |
| |
| /* |
| * When @wait we can deadlock when we interrupt between llist_add() and |
| * arch_send_call_function_ipi*(); when !@wait we can deadlock due to |
| * csd_lock() on because the interrupt context uses the same csd |
| * storage. |
| */ |
| WARN_ON_ONCE(!in_task()); |
| |
| csd = &csd_stack; |
| if (!wait) { |
| csd = this_cpu_ptr(&csd_data); |
| csd_lock(csd); |
| } |
| |
| csd->func = func; |
| csd->info = info; |
| #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
| csd->src = smp_processor_id(); |
| csd->dst = cpu; |
| #endif |
| |
| err = generic_exec_single(cpu, csd); |
| |
| if (wait) |
| csd_lock_wait(csd); |
| |
| put_cpu(); |
| |
| return err; |
| } |
| EXPORT_SYMBOL(smp_call_function_single); |
| |
| /** |
| * smp_call_function_single_async(): Run an asynchronous function on a |
| * specific CPU. |
| * @cpu: The CPU to run on. |
| * @csd: Pre-allocated and setup data structure |
| * |
| * Like smp_call_function_single(), but the call is asynchonous and |
| * can thus be done from contexts with disabled interrupts. |
| * |
| * The caller passes his own pre-allocated data structure |
| * (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. |
| */ |
| int smp_call_function_single_async(int cpu, struct __call_single_data *csd) |
| { |
| int err = 0; |
| |
| preempt_disable(); |
| |
| if (csd->flags & CSD_FLAG_LOCK) { |
| err = -EBUSY; |
| goto out; |
| } |
| |
| csd->flags = CSD_FLAG_LOCK; |
| smp_wmb(); |
| |
| err = generic_exec_single(cpu, csd); |
| |
| out: |
| preempt_enable(); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(smp_call_function_single_async); |
| |
| /* |
| * smp_call_function_any - Run a function on any of the given cpus |
| * @mask: The mask of cpus it can run on. |
| * @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 until function has completed. |
| * |
| * Returns 0 on success, else a negative status code (if no cpus were online). |
| * |
| * Selection preference: |
| * 1) current cpu if in @mask |
| * 2) any cpu of current node if in @mask |
| * 3) any other online cpu in @mask |
| */ |
| int smp_call_function_any(const struct cpumask *mask, |
| smp_call_func_t func, void *info, int wait) |
| { |
| unsigned int cpu; |
| const struct cpumask *nodemask; |
| int ret; |
| |
| /* Try for same CPU (cheapest) */ |
| cpu = get_cpu(); |
| if (cpumask_test_cpu(cpu, mask)) |
| goto call; |
| |
| /* Try for same node. */ |
| nodemask = cpumask_of_node(cpu_to_node(cpu)); |
| for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; |
| cpu = cpumask_next_and(cpu, nodemask, mask)) { |
| if (cpu_online(cpu)) |
| goto call; |
| } |
| |
| /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ |
| cpu = cpumask_any_and(mask, cpu_online_mask); |
| call: |
| ret = smp_call_function_single(cpu, func, info, wait); |
| put_cpu(); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(smp_call_function_any); |
| |
| static void smp_call_function_many_cond(const struct cpumask *mask, |
| smp_call_func_t func, void *info, |
| bool wait, smp_cond_func_t cond_func) |
| { |
| struct call_function_data *cfd; |
| int cpu, next_cpu, this_cpu = smp_processor_id(); |
| |
| /* |
| * Can deadlock when called with interrupts disabled. |
| * 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); |
| |
| /* |
| * When @wait we can deadlock when we interrupt between llist_add() and |
| * arch_send_call_function_ipi*(); when !@wait we can deadlock due to |
| * csd_lock() on because the interrupt context uses the same csd |
| * storage. |
| */ |
| WARN_ON_ONCE(!in_task()); |
| |
| /* 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) { |
| if (!cond_func || cond_func(cpu, info)) |
| 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; |
| |
| cpumask_clear(cfd->cpumask_ipi); |
| for_each_cpu(cpu, cfd->cpumask) { |
| call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu); |
| |
| if (cond_func && !cond_func(cpu, info)) |
| continue; |
| |
| csd_lock(csd); |
| if (wait) |
| csd->flags |= CSD_TYPE_SYNC; |
| csd->func = func; |
| csd->info = info; |
| #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
| csd->src = smp_processor_id(); |
| csd->dst = cpu; |
| #endif |
| if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) |
| __cpumask_set_cpu(cpu, cfd->cpumask_ipi); |
| } |
| |
| /* Send a message to all CPUs in the map */ |
| arch_send_call_function_ipi_mask(cfd->cpumask_ipi); |
| |
| if (wait) { |
| for_each_cpu(cpu, cfd->cpumask) { |
| call_single_data_t *csd; |
| |
| csd = per_cpu_ptr(cfd->csd, cpu); |
| csd_lock_wait(csd); |
| } |
| } |
| } |
| |
| /** |
| * smp_call_function_many(): Run a function on a set of other CPUs. |
| * @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. Preemption |
| * must be disabled when calling this function. |
| */ |
| void smp_call_function_many(const struct cpumask *mask, |
| smp_call_func_t func, void *info, bool wait) |
| { |
| smp_call_function_many_cond(mask, func, info, wait, NULL); |
| } |
| 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. |
| */ |
| void 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(); |
| } |
| 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; |
| |
| if (get_option(&str, &nr_cpus) && 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 */ |
| unsigned 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; |
| } |
| |
| /* Called by boot processor to activate the rest. */ |
| void __init smp_init(void) |
| { |
| int num_nodes, num_cpus; |
| |
| idle_threads_init(); |
| cpuhp_threads_init(); |
| |
| pr_info("Bringing up secondary CPUs ...\n"); |
| |
| bringup_nonboot_cpus(setup_max_cpus); |
| |
| num_nodes = num_online_nodes(); |
| num_cpus = num_online_cpus(); |
| pr_info("Brought up %d node%s, %d CPU%s\n", |
| num_nodes, (num_nodes > 1 ? "s" : ""), |
| num_cpus, (num_cpus > 1 ? "s" : "")); |
| |
| /* Any cleanup work */ |
| 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(). |
| */ |
| void on_each_cpu(smp_call_func_t func, void *info, int wait) |
| { |
| unsigned long flags; |
| |
| preempt_disable(); |
| smp_call_function(func, info, wait); |
| local_irq_save(flags); |
| func(info); |
| local_irq_restore(flags); |
| preempt_enable(); |
| } |
| 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 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. |
| * |
| * 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_mask(smp_cond_func_t cond_func, smp_call_func_t func, |
| void *info, bool wait, const struct cpumask *mask) |
| { |
| int cpu = get_cpu(); |
| |
| smp_call_function_many_cond(mask, func, info, wait, cond_func); |
| if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) { |
| unsigned long flags; |
| |
| local_irq_save(flags); |
| func(info); |
| local_irq_restore(flags); |
| } |
| put_cpu(); |
| } |
| EXPORT_SYMBOL(on_each_cpu_cond_mask); |
| |
| void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func, |
| void *info, bool wait) |
| { |
| on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask); |
| } |
| 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); |
| |
| /** |
| * smp_call_on_cpu - Call a function on a specific cpu |
| * |
| * Used to call a function on a specific cpu and wait for it to return. |
| * Optionally make sure the call is done on a specified physical cpu via vcpu |
| * pinning in order to support virtualized environments. |
| */ |
| struct smp_call_on_cpu_struct { |
| struct work_struct work; |
| struct completion done; |
| int (*func)(void *); |
| void *data; |
| int ret; |
| int cpu; |
| }; |
| |
| static void smp_call_on_cpu_callback(struct work_struct *work) |
| { |
| struct smp_call_on_cpu_struct *sscs; |
| |
| sscs = container_of(work, struct smp_call_on_cpu_struct, work); |
| if (sscs->cpu >= 0) |
| hypervisor_pin_vcpu(sscs->cpu); |
| sscs->ret = sscs->func(sscs->data); |
| if (sscs->cpu >= 0) |
| hypervisor_pin_vcpu(-1); |
| |
| complete(&sscs->done); |
| } |
| |
| int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys) |
| { |
| struct smp_call_on_cpu_struct sscs = { |
| .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), |
| .func = func, |
| .data = par, |
| .cpu = phys ? cpu : -1, |
| }; |
| |
| INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback); |
| |
| if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
| return -ENXIO; |
| |
| queue_work_on(cpu, system_wq, &sscs.work); |
| wait_for_completion(&sscs.done); |
| |
| return sscs.ret; |
| } |
| EXPORT_SYMBOL_GPL(smp_call_on_cpu); |