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This series adds a kernel boot parameter that causes the kernel to panic if one of the call_smp_function() APIs is stalled for more than the specified duration. This is useful in deployments in which a clean panic is preferable to an indefinite stall. -----BEGIN PGP SIGNATURE----- iQJHBAABCgAxFiEEbK7UrM+RBIrCoViJnr8S83LZ+4wFAmU9plITHHBhdWxtY2tA a2VybmVsLm9yZwAKCRCevxLzctn7jB91D/9OiOMtV03TXN2K+zGmJMjTFgLuVnug OqG4mrCv7jTJ3k6fTpu7hih/BCmG1Mu7byyPV6BUSfKsYony7L4yTPFJsjK8lNmq MHh847DErGieuURCDnsvqBVpYIRfXnvW9ptlf+BMCjbzz4FuUu1XhJTm+U2nab3i BEIEMORxDCyghh7yluAVG6sULRXOqjv5VcypwOXUbavDf0JyJTns4QlXFD85yiBr nvfHvLUrzu5EblA3m09lTnCaKrAlz5pwD7fWQq7bS3rz2gndR/DcVcZknQ68FMsj Mcf0Zf45TzyWWfMcE8LCulhMlZ2GYsIm2YkIbgwlsOAndjBrV55rsgaVbSZDke37 QMHPGUZ7m7AjuDqpWZITrJjQHkWCtn/5tFSazHSlMwWg44pgOqvc3OgZn04tzn01 L/guq3yBIKBJiAjdgzdx8/H9S7cSH8TLEWFY2utEAMIjef9Xzi6qwQ4X5p4K9QYJ Sm1hTTCbF9NeyMk0o2rokR58f13+9ewxE4RIYcwP9loo6nbBcTVN/fvdHN6jQywa 7UIui508AUf55zQgO+5z8LsmjyNiDmDIeE8CLeVDicllWN+ne7F//AXAuA5V8m+y G0Mphn/lZpnddDSFlR/QFuMvGqtpIu2y8w93awq8g/VzirbkiiCia3iFcFtss4ip n0Y50CCu/W70fw== =ZD0S -----END PGP SIGNATURE----- Merge tag 'csd-lock.2023.10.23a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull CSD lock update from Paul McKenney: "This adds a kernel boot parameter that causes the kernel to panic if one of the call_smp_function() APIs is stalled for more than the specified duration. This is useful in deployments in which a clean panic is preferable to an indefinite stall" * tag 'csd-lock.2023.10.23a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: smp,csd: Throw an error if a CSD lock is stuck for too long
1126 lines
30 KiB
C
1126 lines
30 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 <linux/jump_label.h>
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#include <trace/events/ipi.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/csd.h>
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#undef CREATE_TRACE_POINTS
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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 DEFINE_PER_CPU(atomic_t, trigger_backtrace) = ATOMIC_INIT(1);
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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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static __always_inline void
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send_call_function_single_ipi(int cpu)
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{
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if (call_function_single_prep_ipi(cpu)) {
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trace_ipi_send_cpu(cpu, _RET_IP_,
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generic_smp_call_function_single_interrupt);
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arch_send_call_function_single_ipi(cpu);
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}
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}
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static __always_inline void
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send_call_function_ipi_mask(struct cpumask *mask)
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{
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trace_ipi_send_cpumask(mask, _RET_IP_,
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generic_smp_call_function_single_interrupt);
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arch_send_call_function_ipi_mask(mask);
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}
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static __always_inline void
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csd_do_func(smp_call_func_t func, void *info, call_single_data_t *csd)
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{
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trace_csd_function_entry(func, csd);
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func(info);
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trace_csd_function_exit(func, csd);
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}
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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug_enabled);
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/*
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* Parse the csdlock_debug= kernel boot parameter.
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*
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* If you need to restore the old "ext" value that once provided
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* additional debugging information, reapply the following commits:
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*
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* de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging")
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* a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging")
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*/
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static int __init csdlock_debug(char *str)
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{
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int ret;
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unsigned int val = 0;
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ret = get_option(&str, &val);
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if (ret) {
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if (val)
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static_branch_enable(&csdlock_debug_enabled);
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else
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static_branch_disable(&csdlock_debug_enabled);
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}
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return 1;
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}
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__setup("csdlock_debug=", csdlock_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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static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */
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module_param(csd_lock_timeout, ulong, 0444);
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static int panic_on_ipistall; /* CSD panic timeout in milliseconds, 300000 for five minutes. */
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module_param(panic_on_ipistall, int, 0444);
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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 void csd_lock_record(call_single_data_t *csd)
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{
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if (static_branch_unlikely(&csdlock_debug_enabled))
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__csd_lock_record(csd);
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}
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static 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 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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unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC;
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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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/* How long since we last checked for a stuck CSD lock.*/
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ts_delta = ts2 - *ts1;
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if (likely(ts_delta <= csd_lock_timeout_ns || csd_lock_timeout_ns == 0))
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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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/* How long since this CSD lock was stuck. */
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ts_delta = ts2 - ts0;
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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(), ts_delta,
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cpu, csd->func, csd->info);
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/*
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* If the CSD lock is still stuck after 5 minutes, it is unlikely
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* to become unstuck. Use a signed comparison to avoid triggering
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* on underflows when the TSC is out of sync between sockets.
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*/
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BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC));
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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 (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace, cpu), 1, 0))
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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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if (firsttime)
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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 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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static __always_inline void csd_lock_wait(call_single_data_t *csd)
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{
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if (static_branch_unlikely(&csdlock_debug_enabled)) {
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__csd_lock_wait(csd);
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return;
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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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#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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* We have to check the type of the CSD before queueing it, because
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* once queued it can have its flags cleared by
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* flush_smp_call_function_queue()
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* even if we haven't sent the smp_call IPI yet (e.g. the stopper
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* executes migration_cpu_stop() on the remote CPU).
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*/
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if (trace_csd_queue_cpu_enabled()) {
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call_single_data_t *csd;
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smp_call_func_t func;
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csd = container_of(node, call_single_data_t, node.llist);
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func = CSD_TYPE(csd) == CSD_TYPE_TTWU ?
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sched_ttwu_pending : csd->func;
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trace_csd_queue_cpu(cpu, _RET_IP_, func, csd);
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}
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/*
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* The list addition should be visible to the target CPU when it pops
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* the head of the list to pull the entry off it in the IPI handler
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* because of normal cache coherency rules implied by the underlying
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* llist ops.
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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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csd_do_func(func, info, NULL);
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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.
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
void generic_smp_call_function_single_interrupt(void)
|
|
{
|
|
__flush_smp_call_function_queue(true);
|
|
}
|
|
|
|
/**
|
|
* __flush_smp_call_function_queue - Flush pending smp-call-function callbacks
|
|
*
|
|
* @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
|
|
* offline CPU. Skip this check if set to 'false'.
|
|
*
|
|
* Flush any pending smp-call-function callbacks queued on this CPU. This is
|
|
* invoked by the generic IPI handler, as well as by a CPU about to go offline,
|
|
* to ensure that all pending IPI callbacks are run before it goes completely
|
|
* offline.
|
|
*
|
|
* Loop through the call_single_queue and run all the queued callbacks.
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
static void __flush_smp_call_function_queue(bool warn_cpu_offline)
|
|
{
|
|
call_single_data_t *csd, *csd_next;
|
|
struct llist_node *entry, *prev;
|
|
struct llist_head *head;
|
|
static bool warned;
|
|
atomic_t *tbt;
|
|
|
|
lockdep_assert_irqs_disabled();
|
|
|
|
/* Allow waiters to send backtrace NMI from here onwards */
|
|
tbt = this_cpu_ptr(&trigger_backtrace);
|
|
atomic_set_release(tbt, 1);
|
|
|
|
head = this_cpu_ptr(&call_single_queue);
|
|
entry = llist_del_all(head);
|
|
entry = llist_reverse_order(entry);
|
|
|
|
/* There shouldn't be any pending callbacks on an offline CPU. */
|
|
if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
|
|
!warned && entry != NULL)) {
|
|
warned = true;
|
|
WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
|
|
|
|
/*
|
|
* We don't have to use the _safe() variant here
|
|
* because we are not invoking the IPI handlers yet.
|
|
*/
|
|
llist_for_each_entry(csd, entry, node.llist) {
|
|
switch (CSD_TYPE(csd)) {
|
|
case CSD_TYPE_ASYNC:
|
|
case CSD_TYPE_SYNC:
|
|
case CSD_TYPE_IRQ_WORK:
|
|
pr_warn("IPI callback %pS sent to offline CPU\n",
|
|
csd->func);
|
|
break;
|
|
|
|
case CSD_TYPE_TTWU:
|
|
pr_warn("IPI task-wakeup sent to offline CPU\n");
|
|
break;
|
|
|
|
default:
|
|
pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
|
|
CSD_TYPE(csd));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* First; run all SYNC callbacks, people are waiting for us.
|
|
*/
|
|
prev = NULL;
|
|
llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
|
|
/* Do we wait until *after* callback? */
|
|
if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
|
|
smp_call_func_t func = csd->func;
|
|
void *info = csd->info;
|
|
|
|
if (prev) {
|
|
prev->next = &csd_next->node.llist;
|
|
} else {
|
|
entry = &csd_next->node.llist;
|
|
}
|
|
|
|
csd_lock_record(csd);
|
|
csd_do_func(func, info, csd);
|
|
csd_unlock(csd);
|
|
csd_lock_record(NULL);
|
|
} else {
|
|
prev = &csd->node.llist;
|
|
}
|
|
}
|
|
|
|
if (!entry)
|
|
return;
|
|
|
|
/*
|
|
* Second; run all !SYNC callbacks.
|
|
*/
|
|
prev = NULL;
|
|
llist_for_each_entry_safe(csd, csd_next, entry, node.llist) {
|
|
int type = CSD_TYPE(csd);
|
|
|
|
if (type != CSD_TYPE_TTWU) {
|
|
if (prev) {
|
|
prev->next = &csd_next->node.llist;
|
|
} else {
|
|
entry = &csd_next->node.llist;
|
|
}
|
|
|
|
if (type == CSD_TYPE_ASYNC) {
|
|
smp_call_func_t func = csd->func;
|
|
void *info = csd->info;
|
|
|
|
csd_lock_record(csd);
|
|
csd_unlock(csd);
|
|
csd_do_func(func, info, csd);
|
|
csd_lock_record(NULL);
|
|
} else if (type == CSD_TYPE_IRQ_WORK) {
|
|
irq_work_single(csd);
|
|
}
|
|
|
|
} else {
|
|
prev = &csd->node.llist;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Third; only CSD_TYPE_TTWU is left, issue those.
|
|
*/
|
|
if (entry) {
|
|
csd = llist_entry(entry, typeof(*csd), node.llist);
|
|
csd_do_func(sched_ttwu_pending, entry, csd);
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* flush_smp_call_function_queue - Flush pending smp-call-function callbacks
|
|
* from task context (idle, migration thread)
|
|
*
|
|
* When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
|
|
* set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
|
|
* setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
|
|
* handle queued SMP function calls before scheduling.
|
|
*
|
|
* The migration thread has to ensure that an eventually pending wakeup has
|
|
* been handled before it migrates a task.
|
|
*/
|
|
void flush_smp_call_function_queue(void)
|
|
{
|
|
unsigned int was_pending;
|
|
unsigned long flags;
|
|
|
|
if (llist_empty(this_cpu_ptr(&call_single_queue)))
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
/* Get the already pending soft interrupts for RT enabled kernels */
|
|
was_pending = local_softirq_pending();
|
|
__flush_smp_call_function_queue(true);
|
|
if (local_softirq_pending())
|
|
do_softirq_post_smp_call_flush(was_pending);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/*
|
|
* smp_call_function_single - Run a function on a specific CPU
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: If true, wait until function has completed on other CPUs.
|
|
*
|
|
* Returns 0 on success, else a negative status code.
|
|
*/
|
|
int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
|
|
int wait)
|
|
{
|
|
call_single_data_t *csd;
|
|
call_single_data_t csd_stack = {
|
|
.node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, },
|
|
};
|
|
int this_cpu;
|
|
int err;
|
|
|
|
/*
|
|
* prevent preemption and reschedule on another processor,
|
|
* as well as CPU removal
|
|
*/
|
|
this_cpu = get_cpu();
|
|
|
|
/*
|
|
* Can deadlock when called with interrupts disabled.
|
|
* We allow cpu's that are not yet online though, as no one else can
|
|
* send smp call function interrupt to this cpu and as such deadlocks
|
|
* can't happen.
|
|
*/
|
|
WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
|
&& !oops_in_progress);
|
|
|
|
/*
|
|
* When @wait we can deadlock when we interrupt between llist_add() and
|
|
* arch_send_call_function_ipi*(); when !@wait we can deadlock due to
|
|
* csd_lock() on because the interrupt context uses the same csd
|
|
* storage.
|
|
*/
|
|
WARN_ON_ONCE(!in_task());
|
|
|
|
csd = &csd_stack;
|
|
if (!wait) {
|
|
csd = this_cpu_ptr(&csd_data);
|
|
csd_lock(csd);
|
|
}
|
|
|
|
csd->func = func;
|
|
csd->info = info;
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
csd->node.src = smp_processor_id();
|
|
csd->node.dst = cpu;
|
|
#endif
|
|
|
|
err = generic_exec_single(cpu, csd);
|
|
|
|
if (wait)
|
|
csd_lock_wait(csd);
|
|
|
|
put_cpu();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function_single);
|
|
|
|
/**
|
|
* smp_call_function_single_async() - Run an asynchronous function on a
|
|
* specific CPU.
|
|
* @cpu: The CPU to run on.
|
|
* @csd: Pre-allocated and setup data structure
|
|
*
|
|
* Like smp_call_function_single(), but the call is asynchonous and
|
|
* can thus be done from contexts with disabled interrupts.
|
|
*
|
|
* The caller passes his own pre-allocated data structure
|
|
* (ie: embedded in an object) and is responsible for synchronizing it
|
|
* such that the IPIs performed on the @csd are strictly serialized.
|
|
*
|
|
* If the function is called with one csd which has not yet been
|
|
* processed by previous call to smp_call_function_single_async(), the
|
|
* function will return immediately with -EBUSY showing that the csd
|
|
* object is still in progress.
|
|
*
|
|
* NOTE: Be careful, there is unfortunately no current debugging facility to
|
|
* validate the correctness of this serialization.
|
|
*
|
|
* Return: %0 on success or negative errno value on error
|
|
*/
|
|
int smp_call_function_single_async(int cpu, 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);
|
|
|
|
/*
|
|
* Flags to be used as scf_flags argument of smp_call_function_many_cond().
|
|
*
|
|
* %SCF_WAIT: Wait until function execution is completed
|
|
* %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask
|
|
*/
|
|
#define SCF_WAIT (1U << 0)
|
|
#define SCF_RUN_LOCAL (1U << 1)
|
|
|
|
static void smp_call_function_many_cond(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info,
|
|
unsigned int scf_flags,
|
|
smp_cond_func_t cond_func)
|
|
{
|
|
int cpu, last_cpu, this_cpu = smp_processor_id();
|
|
struct call_function_data *cfd;
|
|
bool wait = scf_flags & SCF_WAIT;
|
|
int nr_cpus = 0;
|
|
bool run_remote = false;
|
|
bool run_local = false;
|
|
|
|
lockdep_assert_preemption_disabled();
|
|
|
|
/*
|
|
* Can deadlock when called with interrupts disabled.
|
|
* We allow cpu's that are not yet online though, as no one else can
|
|
* send smp call function interrupt to this cpu and as such deadlocks
|
|
* can't happen.
|
|
*/
|
|
if (cpu_online(this_cpu) && !oops_in_progress &&
|
|
!early_boot_irqs_disabled)
|
|
lockdep_assert_irqs_enabled();
|
|
|
|
/*
|
|
* When @wait we can deadlock when we interrupt between llist_add() and
|
|
* arch_send_call_function_ipi*(); when !@wait we can deadlock due to
|
|
* csd_lock() on because the interrupt context uses the same csd
|
|
* storage.
|
|
*/
|
|
WARN_ON_ONCE(!in_task());
|
|
|
|
/* Check if we need local execution. */
|
|
if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
|
|
run_local = true;
|
|
|
|
/* Check if we need remote execution, i.e., any CPU excluding this one. */
|
|
cpu = cpumask_first_and(mask, cpu_online_mask);
|
|
if (cpu == this_cpu)
|
|
cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
|
if (cpu < nr_cpu_ids)
|
|
run_remote = true;
|
|
|
|
if (run_remote) {
|
|
cfd = this_cpu_ptr(&cfd_data);
|
|
cpumask_and(cfd->cpumask, mask, cpu_online_mask);
|
|
__cpumask_clear_cpu(this_cpu, cfd->cpumask);
|
|
|
|
cpumask_clear(cfd->cpumask_ipi);
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
|
|
|
|
if (cond_func && !cond_func(cpu, info)) {
|
|
__cpumask_clear_cpu(cpu, cfd->cpumask);
|
|
continue;
|
|
}
|
|
|
|
csd_lock(csd);
|
|
if (wait)
|
|
csd->node.u_flags |= CSD_TYPE_SYNC;
|
|
csd->func = func;
|
|
csd->info = info;
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
csd->node.src = smp_processor_id();
|
|
csd->node.dst = cpu;
|
|
#endif
|
|
trace_csd_queue_cpu(cpu, _RET_IP_, func, csd);
|
|
|
|
if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
|
|
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
|
|
nr_cpus++;
|
|
last_cpu = cpu;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Choose the most efficient way to send an IPI. Note that the
|
|
* number of CPUs might be zero due to concurrent changes to the
|
|
* provided mask.
|
|
*/
|
|
if (nr_cpus == 1)
|
|
send_call_function_single_ipi(last_cpu);
|
|
else if (likely(nr_cpus > 1))
|
|
send_call_function_ipi_mask(cfd->cpumask_ipi);
|
|
}
|
|
|
|
if (run_local && (!cond_func || cond_func(this_cpu, info))) {
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
csd_do_func(func, info, NULL);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
if (run_remote && wait) {
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
call_single_data_t *csd;
|
|
|
|
csd = per_cpu_ptr(cfd->csd, cpu);
|
|
csd_lock_wait(csd);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* smp_call_function_many(): Run a function on a set of CPUs.
|
|
* @mask: The set of cpus to run on (only runs on online subset).
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: Bitmask that controls the operation. If %SCF_WAIT is set, wait
|
|
* (atomically) until function has completed on other CPUs. If
|
|
* %SCF_RUN_LOCAL is set, the function will also be run locally
|
|
* if the local CPU is set in the @cpumask.
|
|
*
|
|
* If @wait is true, then returns once @func has returned.
|
|
*
|
|
* You must not call this function with disabled interrupts or from a
|
|
* hardware interrupt handler or from a bottom half handler. Preemption
|
|
* must be disabled when calling this function.
|
|
*/
|
|
void smp_call_function_many(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info, bool wait)
|
|
{
|
|
smp_call_function_many_cond(mask, func, info, wait * SCF_WAIT, NULL);
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function_many);
|
|
|
|
/**
|
|
* smp_call_function(): Run a function on all other CPUs.
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: If true, wait (atomically) until function has completed
|
|
* on other CPUs.
|
|
*
|
|
* Returns 0.
|
|
*
|
|
* If @wait is true, then returns once @func has returned; otherwise
|
|
* it returns just before the target cpu calls @func.
|
|
*
|
|
* You must not call this function with disabled interrupts or from a
|
|
* hardware interrupt handler or from a bottom half handler.
|
|
*/
|
|
void smp_call_function(smp_call_func_t func, void *info, int wait)
|
|
{
|
|
preempt_disable();
|
|
smp_call_function_many(cpu_online_mask, func, info, wait);
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function);
|
|
|
|
/* Setup configured maximum number of CPUs to activate */
|
|
unsigned int setup_max_cpus = NR_CPUS;
|
|
EXPORT_SYMBOL(setup_max_cpus);
|
|
|
|
|
|
/*
|
|
* Setup routine for controlling SMP activation
|
|
*
|
|
* Command-line option of "nosmp" or "maxcpus=0" will disable SMP
|
|
* activation entirely (the MPS table probe still happens, though).
|
|
*
|
|
* Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
|
|
* greater than 0, limits the maximum number of CPUs activated in
|
|
* SMP mode to <NUM>.
|
|
*/
|
|
|
|
void __weak __init arch_disable_smp_support(void) { }
|
|
|
|
static int __init nosmp(char *str)
|
|
{
|
|
setup_max_cpus = 0;
|
|
arch_disable_smp_support();
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("nosmp", nosmp);
|
|
|
|
/* this is hard limit */
|
|
static int __init nrcpus(char *str)
|
|
{
|
|
int nr_cpus;
|
|
|
|
if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
|
|
set_nr_cpu_ids(nr_cpus);
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("nr_cpus", nrcpus);
|
|
|
|
static int __init maxcpus(char *str)
|
|
{
|
|
get_option(&str, &setup_max_cpus);
|
|
if (setup_max_cpus == 0)
|
|
arch_disable_smp_support();
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("maxcpus", maxcpus);
|
|
|
|
#if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS)
|
|
/* Setup number of possible processor ids */
|
|
unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
|
|
EXPORT_SYMBOL(nr_cpu_ids);
|
|
#endif
|
|
|
|
/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
|
|
void __init setup_nr_cpu_ids(void)
|
|
{
|
|
set_nr_cpu_ids(find_last_bit(cpumask_bits(cpu_possible_mask), NR_CPUS) + 1);
|
|
}
|
|
|
|
/* Called by boot processor to activate the rest. */
|
|
void __init smp_init(void)
|
|
{
|
|
int num_nodes, num_cpus;
|
|
|
|
idle_threads_init();
|
|
cpuhp_threads_init();
|
|
|
|
pr_info("Bringing up secondary CPUs ...\n");
|
|
|
|
bringup_nonboot_cpus(setup_max_cpus);
|
|
|
|
num_nodes = num_online_nodes();
|
|
num_cpus = num_online_cpus();
|
|
pr_info("Brought up %d node%s, %d CPU%s\n",
|
|
num_nodes, (num_nodes > 1 ? "s" : ""),
|
|
num_cpus, (num_cpus > 1 ? "s" : ""));
|
|
|
|
/* Any cleanup work */
|
|
smp_cpus_done(setup_max_cpus);
|
|
}
|
|
|
|
/*
|
|
* on_each_cpu_cond(): Call a function on each processor for which
|
|
* the supplied function cond_func returns true, optionally waiting
|
|
* for all the required CPUs to finish. This may include the local
|
|
* processor.
|
|
* @cond_func: A callback function that is passed a cpu id and
|
|
* the info parameter. The function is called
|
|
* with preemption disabled. The function should
|
|
* return a blooean value indicating whether to IPI
|
|
* the specified CPU.
|
|
* @func: The function to run on all applicable CPUs.
|
|
* This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to both functions.
|
|
* @wait: If true, wait (atomically) until function has
|
|
* completed on other CPUs.
|
|
*
|
|
* Preemption is disabled to protect against CPUs going offline but not online.
|
|
* CPUs going online during the call will not be seen or sent an IPI.
|
|
*
|
|
* You must not call this function with disabled interrupts or
|
|
* from a hardware interrupt handler or from a bottom half handler.
|
|
*/
|
|
void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
|
|
void *info, bool wait, const struct cpumask *mask)
|
|
{
|
|
unsigned int scf_flags = SCF_RUN_LOCAL;
|
|
|
|
if (wait)
|
|
scf_flags |= SCF_WAIT;
|
|
|
|
preempt_disable();
|
|
smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(on_each_cpu_cond_mask);
|
|
|
|
static void do_nothing(void *unused)
|
|
{
|
|
}
|
|
|
|
/**
|
|
* kick_all_cpus_sync - Force all cpus out of idle
|
|
*
|
|
* Used to synchronize the update of pm_idle function pointer. It's
|
|
* called after the pointer is updated and returns after the dummy
|
|
* callback function has been executed on all cpus. The execution of
|
|
* the function can only happen on the remote cpus after they have
|
|
* left the idle function which had been called via pm_idle function
|
|
* pointer. So it's guaranteed that nothing uses the previous pointer
|
|
* anymore.
|
|
*/
|
|
void kick_all_cpus_sync(void)
|
|
{
|
|
/* Make sure the change is visible before we kick the cpus */
|
|
smp_mb();
|
|
smp_call_function(do_nothing, NULL, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
|
|
|
|
/**
|
|
* wake_up_all_idle_cpus - break all cpus out of idle
|
|
* wake_up_all_idle_cpus try to break all cpus which is in idle state even
|
|
* including idle polling cpus, for non-idle cpus, we will do nothing
|
|
* for them.
|
|
*/
|
|
void wake_up_all_idle_cpus(void)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
preempt_disable();
|
|
if (cpu != smp_processor_id() && cpu_online(cpu))
|
|
wake_up_if_idle(cpu);
|
|
preempt_enable();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
|
|
|
|
/**
|
|
* struct smp_call_on_cpu_struct - Call a function on a specific CPU
|
|
* @work: &work_struct
|
|
* @done: &completion to signal
|
|
* @func: function to call
|
|
* @data: function's data argument
|
|
* @ret: return value from @func
|
|
* @cpu: target CPU (%-1 for any CPU)
|
|
*
|
|
* Used to call a function on a specific cpu and wait for it to return.
|
|
* Optionally make sure the call is done on a specified physical cpu via vcpu
|
|
* pinning in order to support virtualized environments.
|
|
*/
|
|
struct smp_call_on_cpu_struct {
|
|
struct work_struct work;
|
|
struct completion done;
|
|
int (*func)(void *);
|
|
void *data;
|
|
int ret;
|
|
int cpu;
|
|
};
|
|
|
|
static void smp_call_on_cpu_callback(struct work_struct *work)
|
|
{
|
|
struct smp_call_on_cpu_struct *sscs;
|
|
|
|
sscs = container_of(work, struct smp_call_on_cpu_struct, work);
|
|
if (sscs->cpu >= 0)
|
|
hypervisor_pin_vcpu(sscs->cpu);
|
|
sscs->ret = sscs->func(sscs->data);
|
|
if (sscs->cpu >= 0)
|
|
hypervisor_pin_vcpu(-1);
|
|
|
|
complete(&sscs->done);
|
|
}
|
|
|
|
int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
|
|
{
|
|
struct smp_call_on_cpu_struct sscs = {
|
|
.done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
|
|
.func = func,
|
|
.data = par,
|
|
.cpu = phys ? cpu : -1,
|
|
};
|
|
|
|
INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
|
|
|
|
if (cpu >= nr_cpu_ids || !cpu_online(cpu))
|
|
return -ENXIO;
|
|
|
|
queue_work_on(cpu, system_wq, &sscs.work);
|
|
wait_for_completion(&sscs.done);
|
|
|
|
return sscs.ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smp_call_on_cpu);
|