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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /kernel/smp.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kernel/smp.c')
-rw-r--r--kernel/smp.c1125
1 files changed, 1125 insertions, 0 deletions
diff --git a/kernel/smp.c b/kernel/smp.c
new file mode 100644
index 0000000000..695eb13a27
--- /dev/null
+++ b/kernel/smp.c
@@ -0,0 +1,1125 @@
+// 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 <linux/jump_label.h>
+
+#include <trace/events/ipi.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/csd.h>
+#undef CREATE_TRACE_POINTS
+
+#include "smpboot.h"
+#include "sched/smp.h"
+
+#define CSD_TYPE(_csd) ((_csd)->node.u_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 DEFINE_PER_CPU(atomic_t, trigger_backtrace) = ATOMIC_INIT(1);
+
+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());
+}
+
+static __always_inline void
+send_call_function_single_ipi(int cpu)
+{
+ if (call_function_single_prep_ipi(cpu)) {
+ trace_ipi_send_cpu(cpu, _RET_IP_,
+ generic_smp_call_function_single_interrupt);
+ arch_send_call_function_single_ipi(cpu);
+ }
+}
+
+static __always_inline void
+send_call_function_ipi_mask(struct cpumask *mask)
+{
+ trace_ipi_send_cpumask(mask, _RET_IP_,
+ generic_smp_call_function_single_interrupt);
+ arch_send_call_function_ipi_mask(mask);
+}
+
+static __always_inline void
+csd_do_func(smp_call_func_t func, void *info, struct __call_single_data *csd)
+{
+ trace_csd_function_entry(func, csd);
+ func(info);
+ trace_csd_function_exit(func, csd);
+}
+
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+
+static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug_enabled);
+
+/*
+ * Parse the csdlock_debug= kernel boot parameter.
+ *
+ * If you need to restore the old "ext" value that once provided
+ * additional debugging information, reapply the following commits:
+ *
+ * de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging")
+ * a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging")
+ */
+static int __init csdlock_debug(char *str)
+{
+ int ret;
+ unsigned int val = 0;
+
+ ret = get_option(&str, &val);
+ if (ret) {
+ if (val)
+ static_branch_enable(&csdlock_debug_enabled);
+ else
+ static_branch_disable(&csdlock_debug_enabled);
+ }
+
+ return 1;
+}
+__setup("csdlock_debug=", csdlock_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);
+
+static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */
+module_param(csd_lock_timeout, ulong, 0444);
+static int panic_on_ipistall; /* CSD panic timeout in milliseconds, 300000 for five minutes. */
+module_param(panic_on_ipistall, int, 0444);
+
+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 void csd_lock_record(struct __call_single_data *csd)
+{
+ if (static_branch_unlikely(&csdlock_debug_enabled))
+ __csd_lock_record(csd);
+}
+
+static 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->node.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 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->node.u_flags);
+ unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC;
+
+ 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();
+ /* How long since we last checked for a stuck CSD lock.*/
+ ts_delta = ts2 - *ts1;
+ if (likely(ts_delta <= csd_lock_timeout_ns || csd_lock_timeout_ns == 0))
+ 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. */
+ /* How long since this CSD lock was stuck. */
+ ts_delta = ts2 - ts0;
+ 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(), ts_delta,
+ cpu, csd->func, csd->info);
+ /*
+ * If the CSD lock is still stuck after 5 minutes, it is unlikely
+ * to become unstuck. Use a signed comparison to avoid triggering
+ * on underflows when the TSC is out of sync between sockets.
+ */
+ BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC));
+ 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 (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace, cpu), 1, 0))
+ 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);
+ }
+ }
+ if (firsttime)
+ 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 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();
+}
+
+static __always_inline void csd_lock_wait(struct __call_single_data *csd)
+{
+ if (static_branch_unlikely(&csdlock_debug_enabled)) {
+ __csd_lock_wait(csd);
+ return;
+ }
+
+ smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
+}
+#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->node.u_flags, !(VAL & CSD_FLAG_LOCK));
+}
+#endif
+
+static __always_inline void csd_lock(struct __call_single_data *csd)
+{
+ csd_lock_wait(csd);
+ csd->node.u_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->node.u_flags & CSD_FLAG_LOCK));
+
+ /*
+ * ensure we're all done before releasing data:
+ */
+ smp_store_release(&csd->node.u_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)
+{
+ /*
+ * We have to check the type of the CSD before queueing it, because
+ * once queued it can have its flags cleared by
+ * flush_smp_call_function_queue()
+ * even if we haven't sent the smp_call IPI yet (e.g. the stopper
+ * executes migration_cpu_stop() on the remote CPU).
+ */
+ if (trace_csd_queue_cpu_enabled()) {
+ call_single_data_t *csd;
+ smp_call_func_t func;
+
+ csd = container_of(node, call_single_data_t, node.llist);
+ func = CSD_TYPE(csd) == CSD_TYPE_TTWU ?
+ sched_ttwu_pending : csd->func;
+
+ trace_csd_queue_cpu(cpu, _RET_IP_, func, csd);
+ }
+
+ /*
+ * The list addition should be visible to the target CPU when it pops
+ * the head of the list to pull the entry off it in the IPI handler
+ * because of normal cache coherency rules implied by the underlying
+ * llist ops.
+ *
+ * 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);
+ csd_do_func(func, info, NULL);
+ 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->node.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;
+ atomic_t *tbt;
+
+ lockdep_assert_irqs_disabled();
+
+ /* Allow waiters to send backtrace NMI from here onwards */
+ tbt = this_cpu_ptr(&trigger_backtrace);
+ atomic_set_release(tbt, 1);
+
+ 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 && entry != NULL)) {
+ 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, node.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, node.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->node.llist;
+ } else {
+ entry = &csd_next->node.llist;
+ }
+
+ csd_lock_record(csd);
+ csd_do_func(func, info, csd);
+ csd_unlock(csd);
+ csd_lock_record(NULL);
+ } else {
+ prev = &csd->node.llist;
+ }
+ }
+
+ if (!entry)
+ return;
+
+ /*
+ * Second; run all !SYNC callbacks.
+ */
+ prev = NULL;
+ llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
+ int type = CSD_TYPE(csd);
+
+ if (type != CSD_TYPE_TTWU) {
+ if (prev) {
+ prev->next = &csd_next->node.llist;
+ } else {
+ entry = &csd_next->node.llist;
+ }
+
+ if (type == CSD_TYPE_ASYNC) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
+
+ csd_lock_record(csd);
+ csd_unlock(csd);
+ csd_do_func(func, info, csd);
+ csd_lock_record(NULL);
+ } else if (type == CSD_TYPE_IRQ_WORK) {
+ irq_work_single(csd);
+ }
+
+ } else {
+ prev = &csd->node.llist;
+ }
+ }
+
+ /*
+ * Third; only CSD_TYPE_TTWU is left, issue those.
+ */
+ if (entry) {
+ csd = llist_entry(entry, typeof(*csd), node.llist);
+ csd_do_func(sched_ttwu_pending, entry, csd);
+ }
+}
+
+
+/**
+ * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
+ * from task context (idle, migration thread)
+ *
+ * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
+ * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
+ * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
+ * handle queued SMP function calls before scheduling.
+ *
+ * The migration thread has to ensure that an eventually pending wakeup has
+ * been handled before it migrates a task.
+ */
+void flush_smp_call_function_queue(void)
+{
+ unsigned int was_pending;
+ unsigned long flags;
+
+ if (llist_empty(this_cpu_ptr(&call_single_queue)))
+ return;
+
+ local_irq_save(flags);
+ /* Get the already pending soft interrupts for RT enabled kernels */
+ was_pending = local_softirq_pending();
+ __flush_smp_call_function_queue(true);
+ if (local_softirq_pending())
+ do_softirq_post_smp_call_flush(was_pending);
+
+ 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 = {
+ .node = { .u_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->node.src = smp_processor_id();
+ csd->node.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.
+ *
+ * Return: %0 on success or negative errno value on error
+ */
+int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
+{
+ int err = 0;
+
+ preempt_disable();
+
+ if (csd->node.u_flags & CSD_FLAG_LOCK) {
+ err = -EBUSY;
+ goto out;
+ }
+
+ csd->node.u_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);
+
+/*
+ * Flags to be used as scf_flags argument of smp_call_function_many_cond().
+ *
+ * %SCF_WAIT: Wait until function execution is completed
+ * %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask
+ */
+#define SCF_WAIT (1U << 0)
+#define SCF_RUN_LOCAL (1U << 1)
+
+static void smp_call_function_many_cond(const struct cpumask *mask,
+ smp_call_func_t func, void *info,
+ unsigned int scf_flags,
+ smp_cond_func_t cond_func)
+{
+ int cpu, last_cpu, this_cpu = smp_processor_id();
+ struct call_function_data *cfd;
+ bool wait = scf_flags & SCF_WAIT;
+ int nr_cpus = 0;
+ bool run_remote = false;
+ bool run_local = false;
+
+ lockdep_assert_preemption_disabled();
+
+ /*
+ * 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.
+ */
+ if (cpu_online(this_cpu) && !oops_in_progress &&
+ !early_boot_irqs_disabled)
+ lockdep_assert_irqs_enabled();
+
+ /*
+ * 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());
+
+ /* Check if we need local execution. */
+ if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
+ run_local = true;
+
+ /* Check if we need remote execution, i.e., any CPU excluding this one. */
+ cpu = cpumask_first_and(mask, cpu_online_mask);
+ if (cpu == this_cpu)
+ cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+ if (cpu < nr_cpu_ids)
+ run_remote = true;
+
+ if (run_remote) {
+ cfd = this_cpu_ptr(&cfd_data);
+ cpumask_and(cfd->cpumask, mask, cpu_online_mask);
+ __cpumask_clear_cpu(this_cpu, cfd->cpumask);
+
+ 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)) {
+ __cpumask_clear_cpu(cpu, cfd->cpumask);
+ continue;
+ }
+
+ csd_lock(csd);
+ if (wait)
+ csd->node.u_flags |= CSD_TYPE_SYNC;
+ csd->func = func;
+ csd->info = info;
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ csd->node.src = smp_processor_id();
+ csd->node.dst = cpu;
+#endif
+ trace_csd_queue_cpu(cpu, _RET_IP_, func, csd);
+
+ if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
+ __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+ nr_cpus++;
+ last_cpu = cpu;
+ }
+ }
+
+ /*
+ * Choose the most efficient way to send an IPI. Note that the
+ * number of CPUs might be zero due to concurrent changes to the
+ * provided mask.
+ */
+ if (nr_cpus == 1)
+ send_call_function_single_ipi(last_cpu);
+ else if (likely(nr_cpus > 1))
+ send_call_function_ipi_mask(cfd->cpumask_ipi);
+ }
+
+ if (run_local && (!cond_func || cond_func(this_cpu, info))) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ csd_do_func(func, info, NULL);
+ local_irq_restore(flags);
+ }
+
+ if (run_remote && 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 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: Bitmask that controls the operation. If %SCF_WAIT is set, wait
+ * (atomically) until function has completed on other CPUs. If
+ * %SCF_RUN_LOCAL is set, the function will also be run locally
+ * if the local CPU is set in the @cpumask.
+ *
+ * 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 * SCF_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 __init 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)
+ set_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);
+
+#if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS)
+/* Setup number of possible processor ids */
+unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
+EXPORT_SYMBOL(nr_cpu_ids);
+#endif
+
+/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
+void __init setup_nr_cpu_ids(void)
+{
+ set_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);
+}
+
+/*
+ * 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)
+{
+ unsigned int scf_flags = SCF_RUN_LOCAL;
+
+ if (wait)
+ scf_flags |= SCF_WAIT;
+
+ preempt_disable();
+ smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
+ preempt_enable();
+}
+EXPORT_SYMBOL(on_each_cpu_cond_mask);
+
+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;
+
+ for_each_possible_cpu(cpu) {
+ preempt_disable();
+ if (cpu != smp_processor_id() && cpu_online(cpu))
+ wake_up_if_idle(cpu);
+ preempt_enable();
+ }
+}
+EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
+
+/**
+ * struct smp_call_on_cpu_struct - Call a function on a specific CPU
+ * @work: &work_struct
+ * @done: &completion to signal
+ * @func: function to call
+ * @data: function's data argument
+ * @ret: return value from @func
+ * @cpu: target CPU (%-1 for any 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);