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![Sebastian Andrzej Siewior](/assets/img/avatar_default.png)
send_call_function_single_ipi() may wake an idle CPU without sending an
IPI. The woken up CPU will process the SMP-functions in
flush_smp_call_function_from_idle(). Any raised softirq from within the
SMP-function call will not be processed.
Should the CPU have no tasks assigned, then it will go back to idle with
pending softirqs and the NOHZ will rightfully complain.
Process pending softirqs on return from flush_smp_call_function_queue().
Fixes: b2a02fc43a
("smp: Optimize send_call_function_single_ipi()")
Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210123201027.3262800-2-bigeasy@linutronix.de
1015 lines
27 KiB
C
1015 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/interrupt.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)->node.u_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->node.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->node.u_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->node.u_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->node.u_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->node.u_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->node.u_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->node.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, node.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, node.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->node.llist;
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} else {
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entry = &csd_next->node.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->node.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, node.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->node.llist;
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} else {
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entry = &csd_next->node.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->node.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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if (local_softirq_pending())
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do_softirq();
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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 = {
|
|
.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.
|
|
*/
|
|
int smp_call_function_single_async(int cpu, call_single_data_t *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);
|
|
|
|
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->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
|
|
if (llist_add(&csd->node.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);
|