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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Peter Zijlstra](/assets/img/avatar_default.png)
As reported by syzbot and experienced by Pavel, using cpus_read_lock()
in wake_up_all_idle_cpus() generates lock inversion (against mmap_sem
and possibly others).
Instead, shrink the preempt disable region by iterating all CPUs and
checking the online status for each individual CPU while having
preemption disabled.
Fixes: 8850cb663b
("sched: Simplify wake_up_*idle*()")
Reported-by: syzbot+d5b23b18d2f4feae8a67@syzkaller.appspotmail.com
Reported-by: Pavel Machek <pavel@ucw.cz>
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
1237 lines
34 KiB
C
1237 lines
34 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 "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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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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union cfd_seq_cnt {
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u64 val;
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struct {
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u64 src:16;
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u64 dst:16;
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#define CFD_SEQ_NOCPU 0xffff
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u64 type:4;
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#define CFD_SEQ_QUEUE 0
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#define CFD_SEQ_IPI 1
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#define CFD_SEQ_NOIPI 2
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#define CFD_SEQ_PING 3
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#define CFD_SEQ_PINGED 4
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#define CFD_SEQ_HANDLE 5
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#define CFD_SEQ_DEQUEUE 6
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#define CFD_SEQ_IDLE 7
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#define CFD_SEQ_GOTIPI 8
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#define CFD_SEQ_HDLEND 9
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u64 cnt:28;
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} u;
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};
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static char *seq_type[] = {
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[CFD_SEQ_QUEUE] = "queue",
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[CFD_SEQ_IPI] = "ipi",
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[CFD_SEQ_NOIPI] = "noipi",
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[CFD_SEQ_PING] = "ping",
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[CFD_SEQ_PINGED] = "pinged",
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[CFD_SEQ_HANDLE] = "handle",
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[CFD_SEQ_DEQUEUE] = "dequeue (src CPU 0 == empty)",
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[CFD_SEQ_IDLE] = "idle",
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[CFD_SEQ_GOTIPI] = "gotipi",
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[CFD_SEQ_HDLEND] = "hdlend (src CPU 0 == early)",
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};
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struct cfd_seq_local {
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u64 ping;
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u64 pinged;
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u64 handle;
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u64 dequeue;
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u64 idle;
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u64 gotipi;
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u64 hdlend;
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};
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#endif
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struct cfd_percpu {
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call_single_data_t csd;
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#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
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u64 seq_queue;
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u64 seq_ipi;
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u64 seq_noipi;
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#endif
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};
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struct call_function_data {
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struct cfd_percpu __percpu *pcpu;
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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->pcpu = alloc_percpu(struct cfd_percpu);
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if (!cfd->pcpu) {
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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->pcpu);
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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_STATIC_KEY_FALSE(csdlock_debug_enabled);
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static DEFINE_STATIC_KEY_FALSE(csdlock_debug_extended);
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static int __init csdlock_debug(char *str)
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{
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unsigned int val = 0;
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if (str && !strcmp(str, "ext")) {
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val = 1;
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static_branch_enable(&csdlock_debug_extended);
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} else
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get_option(&str, &val);
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if (val)
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static_branch_enable(&csdlock_debug_enabled);
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return 0;
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}
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early_param("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 DEFINE_PER_CPU(struct cfd_seq_local, cfd_seq_local);
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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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static u64 cfd_seq;
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#define CFD_SEQ(s, d, t, c) \
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(union cfd_seq_cnt){ .u.src = s, .u.dst = d, .u.type = t, .u.cnt = c }
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static u64 cfd_seq_inc(unsigned int src, unsigned int dst, unsigned int type)
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{
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union cfd_seq_cnt new, old;
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new = CFD_SEQ(src, dst, type, 0);
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do {
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old.val = READ_ONCE(cfd_seq);
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new.u.cnt = old.u.cnt + 1;
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} while (cmpxchg(&cfd_seq, old.val, new.val) != old.val);
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return old.val;
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}
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#define cfd_seq_store(var, src, dst, type) \
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do { \
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if (static_branch_unlikely(&csdlock_debug_extended)) \
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var = cfd_seq_inc(src, dst, type); \
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} while (0)
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/* Record current CSD work for current CPU, NULL to erase. */
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static void __csd_lock_record(struct __call_single_data *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(struct __call_single_data *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(struct __call_single_data *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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static void cfd_seq_data_add(u64 val, unsigned int src, unsigned int dst,
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unsigned int type, union cfd_seq_cnt *data,
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unsigned int *n_data, unsigned int now)
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{
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union cfd_seq_cnt new[2];
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unsigned int i, j, k;
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new[0].val = val;
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new[1] = CFD_SEQ(src, dst, type, new[0].u.cnt + 1);
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for (i = 0; i < 2; i++) {
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if (new[i].u.cnt <= now)
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new[i].u.cnt |= 0x80000000U;
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for (j = 0; j < *n_data; j++) {
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if (new[i].u.cnt == data[j].u.cnt) {
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/* Direct read value trumps generated one. */
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if (i == 0)
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data[j].val = new[i].val;
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break;
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}
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if (new[i].u.cnt < data[j].u.cnt) {
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for (k = *n_data; k > j; k--)
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data[k].val = data[k - 1].val;
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data[j].val = new[i].val;
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(*n_data)++;
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break;
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}
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}
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if (j == *n_data) {
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data[j].val = new[i].val;
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(*n_data)++;
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}
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}
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}
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static const char *csd_lock_get_type(unsigned int type)
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{
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return (type >= ARRAY_SIZE(seq_type)) ? "?" : seq_type[type];
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}
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static void csd_lock_print_extended(struct __call_single_data *csd, int cpu)
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{
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struct cfd_seq_local *seq = &per_cpu(cfd_seq_local, cpu);
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unsigned int srccpu = csd->node.src;
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struct call_function_data *cfd = per_cpu_ptr(&cfd_data, srccpu);
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struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
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unsigned int now;
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union cfd_seq_cnt data[2 * ARRAY_SIZE(seq_type)];
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unsigned int n_data = 0, i;
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data[0].val = READ_ONCE(cfd_seq);
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now = data[0].u.cnt;
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cfd_seq_data_add(pcpu->seq_queue, srccpu, cpu, CFD_SEQ_QUEUE, data, &n_data, now);
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cfd_seq_data_add(pcpu->seq_ipi, srccpu, cpu, CFD_SEQ_IPI, data, &n_data, now);
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cfd_seq_data_add(pcpu->seq_noipi, srccpu, cpu, CFD_SEQ_NOIPI, data, &n_data, now);
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cfd_seq_data_add(per_cpu(cfd_seq_local.ping, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PING, data, &n_data, now);
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cfd_seq_data_add(per_cpu(cfd_seq_local.pinged, srccpu), srccpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED, data, &n_data, now);
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cfd_seq_data_add(seq->idle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_IDLE, data, &n_data, now);
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cfd_seq_data_add(seq->gotipi, CFD_SEQ_NOCPU, cpu, CFD_SEQ_GOTIPI, data, &n_data, now);
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cfd_seq_data_add(seq->handle, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HANDLE, data, &n_data, now);
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cfd_seq_data_add(seq->dequeue, CFD_SEQ_NOCPU, cpu, CFD_SEQ_DEQUEUE, data, &n_data, now);
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cfd_seq_data_add(seq->hdlend, CFD_SEQ_NOCPU, cpu, CFD_SEQ_HDLEND, data, &n_data, now);
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for (i = 0; i < n_data; i++) {
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pr_alert("\tcsd: cnt(%07x): %04x->%04x %s\n",
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data[i].u.cnt & ~0x80000000U, data[i].u.src,
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data[i].u.dst, csd_lock_get_type(data[i].u.type));
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}
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pr_alert("\tcsd: cnt now: %07x\n", now);
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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(struct __call_single_data *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 (static_branch_unlikely(&csdlock_debug_extended))
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csd_lock_print_extended(csd, cpu);
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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 void __csd_lock_wait(struct __call_single_data *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(struct __call_single_data *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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static void __smp_call_single_queue_debug(int cpu, struct llist_node *node)
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{
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unsigned int this_cpu = smp_processor_id();
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struct cfd_seq_local *seq = this_cpu_ptr(&cfd_seq_local);
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struct call_function_data *cfd = this_cpu_ptr(&cfd_data);
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struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
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cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
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if (llist_add(node, &per_cpu(call_single_queue, cpu))) {
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cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
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cfd_seq_store(seq->ping, this_cpu, cpu, CFD_SEQ_PING);
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send_call_function_single_ipi(cpu);
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cfd_seq_store(seq->pinged, this_cpu, cpu, CFD_SEQ_PINGED);
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} else {
|
|
cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
|
|
}
|
|
}
|
|
#else
|
|
#define cfd_seq_store(var, src, dst, type)
|
|
|
|
static void csd_lock_record(struct __call_single_data *csd)
|
|
{
|
|
}
|
|
|
|
static __always_inline void csd_lock_wait(struct __call_single_data *csd)
|
|
{
|
|
smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
|
|
}
|
|
#endif
|
|
|
|
static __always_inline void csd_lock(struct __call_single_data *csd)
|
|
{
|
|
csd_lock_wait(csd);
|
|
csd->node.u_flags |= CSD_FLAG_LOCK;
|
|
|
|
/*
|
|
* prevent CPU from reordering the above assignment
|
|
* to ->flags with any subsequent assignments to other
|
|
* fields of the specified call_single_data_t structure:
|
|
*/
|
|
smp_wmb();
|
|
}
|
|
|
|
static __always_inline void csd_unlock(struct __call_single_data *csd)
|
|
{
|
|
WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK));
|
|
|
|
/*
|
|
* ensure we're all done before releasing data:
|
|
*/
|
|
smp_store_release(&csd->node.u_flags, 0);
|
|
}
|
|
|
|
static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
|
|
|
|
void __smp_call_single_queue(int cpu, struct llist_node *node)
|
|
{
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
if (static_branch_unlikely(&csdlock_debug_extended)) {
|
|
unsigned int type;
|
|
|
|
type = CSD_TYPE(container_of(node, call_single_data_t,
|
|
node.llist));
|
|
if (type == CSD_TYPE_SYNC || type == CSD_TYPE_ASYNC) {
|
|
__smp_call_single_queue_debug(cpu, node);
|
|
return;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* The list addition should be visible before sending the IPI
|
|
* handler locks the list to pull the entry off it because of
|
|
* normal cache coherency rules implied by spinlocks.
|
|
*
|
|
* If IPIs can go out of order to the cache coherency protocol
|
|
* in an architecture, sufficient synchronisation should be added
|
|
* to arch code to make it appear to obey cache coherency WRT
|
|
* locking and barrier primitives. Generic code isn't really
|
|
* equipped to do the right thing...
|
|
*/
|
|
if (llist_add(node, &per_cpu(call_single_queue, cpu)))
|
|
send_call_function_single_ipi(cpu);
|
|
}
|
|
|
|
/*
|
|
* Insert a previously allocated call_single_data_t element
|
|
* for execution on the given CPU. data must already have
|
|
* ->func, ->info, and ->flags set.
|
|
*/
|
|
static int generic_exec_single(int cpu, struct __call_single_data *csd)
|
|
{
|
|
if (cpu == smp_processor_id()) {
|
|
smp_call_func_t func = csd->func;
|
|
void *info = csd->info;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* We can unlock early even for the synchronous on-stack case,
|
|
* since we're doing this from the same CPU..
|
|
*/
|
|
csd_lock_record(csd);
|
|
csd_unlock(csd);
|
|
local_irq_save(flags);
|
|
func(info);
|
|
csd_lock_record(NULL);
|
|
local_irq_restore(flags);
|
|
return 0;
|
|
}
|
|
|
|
if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
|
|
csd_unlock(csd);
|
|
return -ENXIO;
|
|
}
|
|
|
|
__smp_call_single_queue(cpu, &csd->node.llist);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
|
|
*
|
|
* Invoked by arch to handle an IPI for call function single.
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
void generic_smp_call_function_single_interrupt(void)
|
|
{
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->gotipi, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_GOTIPI);
|
|
flush_smp_call_function_queue(true);
|
|
}
|
|
|
|
/**
|
|
* flush_smp_call_function_queue - Flush pending smp-call-function callbacks
|
|
*
|
|
* @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
|
|
* offline CPU. Skip this check if set to 'false'.
|
|
*
|
|
* Flush any pending smp-call-function callbacks queued on this CPU. This is
|
|
* invoked by the generic IPI handler, as well as by a CPU about to go offline,
|
|
* to ensure that all pending IPI callbacks are run before it goes completely
|
|
* offline.
|
|
*
|
|
* Loop through the call_single_queue and run all the queued callbacks.
|
|
* Must be called with interrupts disabled.
|
|
*/
|
|
static void flush_smp_call_function_queue(bool warn_cpu_offline)
|
|
{
|
|
call_single_data_t *csd, *csd_next;
|
|
struct llist_node *entry, *prev;
|
|
struct llist_head *head;
|
|
static bool warned;
|
|
|
|
lockdep_assert_irqs_disabled();
|
|
|
|
head = this_cpu_ptr(&call_single_queue);
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->handle, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_HANDLE);
|
|
entry = llist_del_all(head);
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->dequeue,
|
|
/* Special meaning of source cpu: 0 == queue empty */
|
|
entry ? CFD_SEQ_NOCPU : 0,
|
|
smp_processor_id(), CFD_SEQ_DEQUEUE);
|
|
entry = llist_reverse_order(entry);
|
|
|
|
/* There shouldn't be any pending callbacks on an offline CPU. */
|
|
if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
|
|
!warned && !llist_empty(head))) {
|
|
warned = true;
|
|
WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
|
|
|
|
/*
|
|
* We don't have to use the _safe() variant here
|
|
* because we are not invoking the IPI handlers yet.
|
|
*/
|
|
llist_for_each_entry(csd, entry, 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);
|
|
func(info);
|
|
csd_unlock(csd);
|
|
csd_lock_record(NULL);
|
|
} else {
|
|
prev = &csd->node.llist;
|
|
}
|
|
}
|
|
|
|
if (!entry) {
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend,
|
|
0, smp_processor_id(),
|
|
CFD_SEQ_HDLEND);
|
|
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);
|
|
func(info);
|
|
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)
|
|
sched_ttwu_pending(entry);
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->hdlend, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_HDLEND);
|
|
}
|
|
|
|
void flush_smp_call_function_from_idle(void)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (llist_empty(this_cpu_ptr(&call_single_queue)))
|
|
return;
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
|
|
smp_processor_id(), CFD_SEQ_IDLE);
|
|
local_irq_save(flags);
|
|
flush_smp_call_function_queue(true);
|
|
if (local_softirq_pending())
|
|
do_softirq();
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/*
|
|
* smp_call_function_single - Run a function on a specific CPU
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: If true, wait until function has completed on other CPUs.
|
|
*
|
|
* Returns 0 on success, else a negative status code.
|
|
*/
|
|
int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
|
|
int wait)
|
|
{
|
|
call_single_data_t *csd;
|
|
call_single_data_t csd_stack = {
|
|
.node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, },
|
|
};
|
|
int this_cpu;
|
|
int err;
|
|
|
|
/*
|
|
* prevent preemption and reschedule on another processor,
|
|
* as well as CPU removal
|
|
*/
|
|
this_cpu = get_cpu();
|
|
|
|
/*
|
|
* Can deadlock when called with interrupts disabled.
|
|
* We allow cpu's that are not yet online though, as no one else can
|
|
* send smp call function interrupt to this cpu and as such deadlocks
|
|
* can't happen.
|
|
*/
|
|
WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
|
&& !oops_in_progress);
|
|
|
|
/*
|
|
* When @wait we can deadlock when we interrupt between llist_add() and
|
|
* arch_send_call_function_ipi*(); when !@wait we can deadlock due to
|
|
* csd_lock() on because the interrupt context uses the same csd
|
|
* storage.
|
|
*/
|
|
WARN_ON_ONCE(!in_task());
|
|
|
|
csd = &csd_stack;
|
|
if (!wait) {
|
|
csd = this_cpu_ptr(&csd_data);
|
|
csd_lock(csd);
|
|
}
|
|
|
|
csd->func = func;
|
|
csd->info = info;
|
|
#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
|
|
csd->node.src = smp_processor_id();
|
|
csd->node.dst = cpu;
|
|
#endif
|
|
|
|
err = generic_exec_single(cpu, csd);
|
|
|
|
if (wait)
|
|
csd_lock_wait(csd);
|
|
|
|
put_cpu();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(smp_call_function_single);
|
|
|
|
/**
|
|
* smp_call_function_single_async() - Run an asynchronous function on a
|
|
* specific CPU.
|
|
* @cpu: The CPU to run on.
|
|
* @csd: Pre-allocated and setup data structure
|
|
*
|
|
* Like smp_call_function_single(), but the call is asynchonous and
|
|
* can thus be done from contexts with disabled interrupts.
|
|
*
|
|
* The caller passes his own pre-allocated data structure
|
|
* (ie: embedded in an object) and is responsible for synchronizing it
|
|
* such that the IPIs performed on the @csd are strictly serialized.
|
|
*
|
|
* If the function is called with one csd which has not yet been
|
|
* processed by previous call to smp_call_function_single_async(), the
|
|
* function will return immediately with -EBUSY showing that the csd
|
|
* object is still in progress.
|
|
*
|
|
* NOTE: Be careful, there is unfortunately no current debugging facility to
|
|
* validate the correctness of this serialization.
|
|
*
|
|
* Return: %0 on success or negative errno value on error
|
|
*/
|
|
int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
|
|
{
|
|
int err = 0;
|
|
|
|
preempt_disable();
|
|
|
|
if (csd->node.u_flags & CSD_FLAG_LOCK) {
|
|
err = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
csd->node.u_flags = CSD_FLAG_LOCK;
|
|
smp_wmb();
|
|
|
|
err = generic_exec_single(cpu, csd);
|
|
|
|
out:
|
|
preempt_enable();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smp_call_function_single_async);
|
|
|
|
/*
|
|
* smp_call_function_any - Run a function on any of the given cpus
|
|
* @mask: The mask of cpus it can run on.
|
|
* @func: The function to run. This must be fast and non-blocking.
|
|
* @info: An arbitrary pointer to pass to the function.
|
|
* @wait: If true, wait until function has completed.
|
|
*
|
|
* Returns 0 on success, else a negative status code (if no cpus were online).
|
|
*
|
|
* Selection preference:
|
|
* 1) current cpu if in @mask
|
|
* 2) any cpu of current node if in @mask
|
|
* 3) any other online cpu in @mask
|
|
*/
|
|
int smp_call_function_any(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info, int wait)
|
|
{
|
|
unsigned int cpu;
|
|
const struct cpumask *nodemask;
|
|
int ret;
|
|
|
|
/* Try for same CPU (cheapest) */
|
|
cpu = get_cpu();
|
|
if (cpumask_test_cpu(cpu, mask))
|
|
goto call;
|
|
|
|
/* Try for same node. */
|
|
nodemask = cpumask_of_node(cpu_to_node(cpu));
|
|
for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
|
|
cpu = cpumask_next_and(cpu, nodemask, mask)) {
|
|
if (cpu_online(cpu))
|
|
goto call;
|
|
}
|
|
|
|
/* Any online will do: smp_call_function_single handles nr_cpu_ids. */
|
|
cpu = cpumask_any_and(mask, cpu_online_mask);
|
|
call:
|
|
ret = smp_call_function_single(cpu, func, info, wait);
|
|
put_cpu();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smp_call_function_any);
|
|
|
|
/*
|
|
* Flags to be used as scf_flags argument of smp_call_function_many_cond().
|
|
*
|
|
* %SCF_WAIT: Wait until function execution is completed
|
|
* %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask
|
|
*/
|
|
#define SCF_WAIT (1U << 0)
|
|
#define SCF_RUN_LOCAL (1U << 1)
|
|
|
|
static void smp_call_function_many_cond(const struct cpumask *mask,
|
|
smp_call_func_t func, void *info,
|
|
unsigned int scf_flags,
|
|
smp_cond_func_t cond_func)
|
|
{
|
|
int cpu, last_cpu, this_cpu = smp_processor_id();
|
|
struct call_function_data *cfd;
|
|
bool wait = scf_flags & SCF_WAIT;
|
|
bool run_remote = false;
|
|
bool run_local = false;
|
|
int nr_cpus = 0;
|
|
|
|
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) {
|
|
struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
|
|
call_single_data_t *csd = &pcpu->csd;
|
|
|
|
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
|
|
cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
|
|
if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
|
|
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
|
|
nr_cpus++;
|
|
last_cpu = cpu;
|
|
|
|
cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
|
|
} else {
|
|
cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
|
|
}
|
|
}
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->ping, this_cpu, CFD_SEQ_NOCPU, CFD_SEQ_PING);
|
|
|
|
/*
|
|
* 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))
|
|
arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
|
|
|
|
cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->pinged, this_cpu, CFD_SEQ_NOCPU, CFD_SEQ_PINGED);
|
|
}
|
|
|
|
if (run_local && (!cond_func || cond_func(this_cpu, info))) {
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
func(info);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
if (run_remote && wait) {
|
|
for_each_cpu(cpu, cfd->cpumask) {
|
|
call_single_data_t *csd;
|
|
|
|
csd = &per_cpu_ptr(cfd->pcpu, cpu)->csd;
|
|
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 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);
|
|
}
|
|
|
|
/*
|
|
* 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);
|