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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Linus Torvalds](/assets/img/avatar_default.png)
Pull RCU changes from Ingo Molnar: - Debugging for smp_call_function() - RT raw/non-raw lock ordering fixes - Strict grace periods for KASAN - New smp_call_function() torture test - Torture-test updates - Documentation updates - Miscellaneous fixes [ This doesn't actually pull the tag - I've dropped the last merge from the RCU branch due to questions about the series. - Linus ] * tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) smp: Make symbol 'csd_bug_count' static kernel/smp: Provide CSD lock timeout diagnostics smp: Add source and destination CPUs to __call_single_data rcu: Shrink each possible cpu krcp rcu/segcblist: Prevent useless GP start if no CBs to accelerate torture: Add gdb support rcutorture: Allow pointer leaks to test diagnostic code rcutorture: Hoist OOM registry up one level refperf: Avoid null pointer dereference when buf fails to allocate rcutorture: Properly synchronize with OOM notifier rcutorture: Properly set rcu_fwds for OOM handling torture: Add kvm.sh --help and update help message rcutorture: Add CONFIG_PROVE_RCU_LIST to TREE05 torture: Update initrd documentation rcutorture: Replace HTTP links with HTTPS ones locktorture: Make function torture_percpu_rwsem_init() static torture: document --allcpus argument added to the kvm.sh script rcutorture: Output number of elapsed grace periods rcutorture: Remove KCSAN stubs rcu: Remove unused "cpu" parameter from rcu_report_qs_rdp() ...
1011 lines
27 KiB
C
1011 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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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 <linux/sched/idle.h>
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#include <linux/hypervisor.h>
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#include <linux/sched/clock.h>
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#include <linux/nmi.h>
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#include <linux/sched/debug.h>
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#include "smpboot.h"
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#include "sched/smp.h"
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#define CSD_TYPE(_csd) ((_csd)->flags & CSD_FLAG_TYPE_MASK)
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struct call_function_data {
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call_single_data_t __percpu *csd;
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cpumask_var_t cpumask;
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cpumask_var_t cpumask_ipi;
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};
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static DEFINE_PER_CPU_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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int smpcfd_prepare_cpu(unsigned int cpu)
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{
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struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
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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 -ENOMEM;
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if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
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cpu_to_node(cpu))) {
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free_cpumask_var(cfd->cpumask);
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return -ENOMEM;
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}
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cfd->csd = alloc_percpu(call_single_data_t);
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if (!cfd->csd) {
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free_cpumask_var(cfd->cpumask);
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free_cpumask_var(cfd->cpumask_ipi);
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return -ENOMEM;
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}
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return 0;
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}
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int smpcfd_dead_cpu(unsigned int cpu)
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{
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struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
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free_cpumask_var(cfd->cpumask);
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free_cpumask_var(cfd->cpumask_ipi);
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free_percpu(cfd->csd);
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return 0;
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}
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int smpcfd_dying_cpu(unsigned int cpu)
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{
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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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irq_work_run();
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return 0;
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}
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void __init call_function_init(void)
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{
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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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smpcfd_prepare_cpu(smp_processor_id());
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}
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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
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static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
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static DEFINE_PER_CPU(void *, cur_csd_info);
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#define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC)
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static atomic_t csd_bug_count = ATOMIC_INIT(0);
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/* Record current CSD work for current CPU, NULL to erase. */
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static void csd_lock_record(call_single_data_t *csd)
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{
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if (!csd) {
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smp_mb(); /* NULL cur_csd after unlock. */
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__this_cpu_write(cur_csd, NULL);
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return;
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}
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__this_cpu_write(cur_csd_func, csd->func);
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__this_cpu_write(cur_csd_info, csd->info);
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smp_wmb(); /* func and info before csd. */
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__this_cpu_write(cur_csd, csd);
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smp_mb(); /* Update cur_csd before function call. */
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/* Or before unlock, as the case may be. */
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}
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static __always_inline int csd_lock_wait_getcpu(call_single_data_t *csd)
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{
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unsigned int csd_type;
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csd_type = CSD_TYPE(csd);
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if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC)
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return csd->dst; /* Other CSD_TYPE_ values might not have ->dst. */
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return -1;
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}
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/*
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* Complain if too much time spent waiting. Note that only
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* the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
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* so waiting on other types gets much less information.
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*/
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static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
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{
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int cpu = -1;
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int cpux;
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bool firsttime;
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u64 ts2, ts_delta;
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call_single_data_t *cpu_cur_csd;
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unsigned int flags = READ_ONCE(csd->flags);
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if (!(flags & CSD_FLAG_LOCK)) {
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if (!unlikely(*bug_id))
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return true;
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cpu = csd_lock_wait_getcpu(csd);
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pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
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*bug_id, raw_smp_processor_id(), cpu);
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return true;
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}
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ts2 = sched_clock();
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ts_delta = ts2 - *ts1;
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if (likely(ts_delta <= CSD_LOCK_TIMEOUT))
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return false;
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firsttime = !*bug_id;
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if (firsttime)
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*bug_id = atomic_inc_return(&csd_bug_count);
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cpu = csd_lock_wait_getcpu(csd);
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if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
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cpux = 0;
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else
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cpux = cpu;
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cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
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pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
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firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0,
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cpu, csd->func, csd->info);
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if (cpu_cur_csd && csd != cpu_cur_csd) {
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pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
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*bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
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READ_ONCE(per_cpu(cur_csd_info, cpux)));
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} else {
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pr_alert("\tcsd: CSD lock (#%d) %s.\n",
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*bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
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}
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if (cpu >= 0) {
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if (!trigger_single_cpu_backtrace(cpu))
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dump_cpu_task(cpu);
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if (!cpu_cur_csd) {
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pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
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arch_send_call_function_single_ipi(cpu);
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}
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}
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dump_stack();
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*ts1 = ts2;
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return false;
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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(call_single_data_t *csd)
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{
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int bug_id = 0;
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u64 ts0, ts1;
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ts1 = ts0 = sched_clock();
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for (;;) {
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if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id))
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break;
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cpu_relax();
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}
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smp_acquire__after_ctrl_dep();
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}
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#else
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static void csd_lock_record(call_single_data_t *csd)
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{
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}
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static __always_inline void csd_lock_wait(call_single_data_t *csd)
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{
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smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
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}
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#endif
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static __always_inline void csd_lock(call_single_data_t *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_t 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(call_single_data_t *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(call_single_data_t, csd_data);
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void __smp_call_single_queue(int cpu, struct llist_node *node)
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{
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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(node, &per_cpu(call_single_queue, cpu)))
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send_call_function_single_ipi(cpu);
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}
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/*
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* Insert a previously allocated call_single_data_t 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, call_single_data_t *csd)
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{
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if (cpu == smp_processor_id()) {
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smp_call_func_t func = csd->func;
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void *info = csd->info;
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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_lock_record(csd);
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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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csd_lock_record(NULL);
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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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__smp_call_single_queue(cpu, &csd->llist);
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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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call_single_data_t *csd, *csd_next;
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struct llist_node *entry, *prev;
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struct llist_head *head;
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static bool warned;
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lockdep_assert_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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switch (CSD_TYPE(csd)) {
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case CSD_TYPE_ASYNC:
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case CSD_TYPE_SYNC:
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case CSD_TYPE_IRQ_WORK:
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pr_warn("IPI callback %pS sent to offline CPU\n",
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csd->func);
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break;
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case CSD_TYPE_TTWU:
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pr_warn("IPI task-wakeup sent to offline CPU\n");
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break;
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default:
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pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
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CSD_TYPE(csd));
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break;
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}
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}
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}
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/*
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* First; run all SYNC callbacks, people are waiting for us.
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*/
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prev = NULL;
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llist_for_each_entry_safe(csd, csd_next, entry, llist) {
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/* Do we wait until *after* callback? */
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if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
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smp_call_func_t func = csd->func;
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void *info = csd->info;
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if (prev) {
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prev->next = &csd_next->llist;
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} else {
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entry = &csd_next->llist;
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}
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csd_lock_record(csd);
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func(info);
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csd_unlock(csd);
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csd_lock_record(NULL);
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} else {
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prev = &csd->llist;
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}
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}
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if (!entry)
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return;
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/*
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* Second; run all !SYNC callbacks.
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*/
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prev = NULL;
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llist_for_each_entry_safe(csd, csd_next, entry, llist) {
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int type = CSD_TYPE(csd);
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if (type != CSD_TYPE_TTWU) {
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if (prev) {
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prev->next = &csd_next->llist;
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} else {
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entry = &csd_next->llist;
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}
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if (type == CSD_TYPE_ASYNC) {
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smp_call_func_t func = csd->func;
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void *info = csd->info;
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csd_lock_record(csd);
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csd_unlock(csd);
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func(info);
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csd_lock_record(NULL);
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} else if (type == CSD_TYPE_IRQ_WORK) {
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irq_work_single(csd);
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}
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} else {
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prev = &csd->llist;
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}
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}
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/*
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* Third; only CSD_TYPE_TTWU is left, issue those.
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*/
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if (entry)
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sched_ttwu_pending(entry);
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}
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void flush_smp_call_function_from_idle(void)
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{
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unsigned long flags;
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if (llist_empty(this_cpu_ptr(&call_single_queue)))
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return;
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local_irq_save(flags);
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flush_smp_call_function_queue(true);
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local_irq_restore(flags);
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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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call_single_data_t *csd;
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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, call_single_data_t *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)
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{
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struct smp_call_on_cpu_struct *sscs;
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|
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sscs = container_of(work, struct smp_call_on_cpu_struct, work);
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if (sscs->cpu >= 0)
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hypervisor_pin_vcpu(sscs->cpu);
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sscs->ret = sscs->func(sscs->data);
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if (sscs->cpu >= 0)
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hypervisor_pin_vcpu(-1);
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complete(&sscs->done);
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}
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int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
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{
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struct smp_call_on_cpu_struct sscs = {
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.done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
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.func = func,
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.data = par,
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.cpu = phys ? cpu : -1,
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};
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|
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INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
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|
|
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if (cpu >= nr_cpu_ids || !cpu_online(cpu))
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return -ENXIO;
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|
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queue_work_on(cpu, system_wq, &sscs.work);
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wait_for_completion(&sscs.done);
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|
|
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return sscs.ret;
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}
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EXPORT_SYMBOL_GPL(smp_call_on_cpu);
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