Linux kernel mirror (for testing)
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1#ifndef _LINUX_STOP_MACHINE
2#define _LINUX_STOP_MACHINE
3
4#include <linux/cpu.h>
5#include <linux/cpumask.h>
6#include <linux/smp.h>
7#include <linux/list.h>
8
9/*
10 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
11 * monopolization mechanism. The caller can specify a non-sleeping
12 * function to be executed on a single or multiple cpus preempting all
13 * other processes and monopolizing those cpus until it finishes.
14 *
15 * Resources for this mechanism are preallocated when a cpu is brought
16 * up and requests are guaranteed to be served as long as the target
17 * cpus are online.
18 */
19typedef int (*cpu_stop_fn_t)(void *arg);
20
21#ifdef CONFIG_SMP
22
23struct cpu_stop_work {
24 struct list_head list; /* cpu_stopper->works */
25 cpu_stop_fn_t fn;
26 void *arg;
27 struct cpu_stop_done *done;
28};
29
30int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
31int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg);
32bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
33 struct cpu_stop_work *work_buf);
34int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
35int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
36void stop_machine_park(int cpu);
37void stop_machine_unpark(int cpu);
38
39#else /* CONFIG_SMP */
40
41#include <linux/workqueue.h>
42
43struct cpu_stop_work {
44 struct work_struct work;
45 cpu_stop_fn_t fn;
46 void *arg;
47};
48
49static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
50{
51 int ret = -ENOENT;
52 preempt_disable();
53 if (cpu == smp_processor_id())
54 ret = fn(arg);
55 preempt_enable();
56 return ret;
57}
58
59static void stop_one_cpu_nowait_workfn(struct work_struct *work)
60{
61 struct cpu_stop_work *stwork =
62 container_of(work, struct cpu_stop_work, work);
63 preempt_disable();
64 stwork->fn(stwork->arg);
65 preempt_enable();
66}
67
68static inline bool stop_one_cpu_nowait(unsigned int cpu,
69 cpu_stop_fn_t fn, void *arg,
70 struct cpu_stop_work *work_buf)
71{
72 if (cpu == smp_processor_id()) {
73 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
74 work_buf->fn = fn;
75 work_buf->arg = arg;
76 schedule_work(&work_buf->work);
77 return true;
78 }
79
80 return false;
81}
82
83static inline int stop_cpus(const struct cpumask *cpumask,
84 cpu_stop_fn_t fn, void *arg)
85{
86 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
87 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
88 return -ENOENT;
89}
90
91static inline int try_stop_cpus(const struct cpumask *cpumask,
92 cpu_stop_fn_t fn, void *arg)
93{
94 return stop_cpus(cpumask, fn, arg);
95}
96
97#endif /* CONFIG_SMP */
98
99/*
100 * stop_machine "Bogolock": stop the entire machine, disable
101 * interrupts. This is a very heavy lock, which is equivalent to
102 * grabbing every spinlock (and more). So the "read" side to such a
103 * lock is anything which disables preemption.
104 */
105#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
106
107/**
108 * stop_machine: freeze the machine on all CPUs and run this function
109 * @fn: the function to run
110 * @data: the data ptr for the @fn()
111 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
112 *
113 * Description: This causes a thread to be scheduled on every cpu,
114 * each of which disables interrupts. The result is that no one is
115 * holding a spinlock or inside any other preempt-disabled region when
116 * @fn() runs.
117 *
118 * This can be thought of as a very heavy write lock, equivalent to
119 * grabbing every spinlock in the kernel.
120 *
121 * Protects against CPU hotplug.
122 */
123int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
124
125/**
126 * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function
127 * @fn: the function to run
128 * @data: the data ptr for the @fn()
129 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
130 *
131 * Same as above. Must be called from with in a cpus_read_lock() protected
132 * region. Avoids nested calls to cpus_read_lock().
133 */
134int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
135
136int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
137 const struct cpumask *cpus);
138#else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
139
140static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,
141 const struct cpumask *cpus)
142{
143 unsigned long flags;
144 int ret;
145 local_irq_save(flags);
146 ret = fn(data);
147 local_irq_restore(flags);
148 return ret;
149}
150
151static inline int stop_machine(cpu_stop_fn_t fn, void *data,
152 const struct cpumask *cpus)
153{
154 return stop_machine_cpuslocked(fn, data, cpus);
155}
156
157static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
158 const struct cpumask *cpus)
159{
160 return stop_machine(fn, data, cpus);
161}
162
163#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
164#endif /* _LINUX_STOP_MACHINE */