summaryrefslogtreecommitdiffstats
path: root/include/linux/stop_machine.h
blob: e0f2da25d751a50e3ca52e7c3d044b9765cd53dc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
#ifndef _LINUX_STOP_MACHINE
#define _LINUX_STOP_MACHINE

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/list.h>
#include <asm/system.h>

/*
 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
 * monopolization mechanism.  The caller can specify a non-sleeping
 * function to be executed on a single or multiple cpus preempting all
 * other processes and monopolizing those cpus until it finishes.
 *
 * Resources for this mechanism are preallocated when a cpu is brought
 * up and requests are guaranteed to be served as long as the target
 * cpus are online.
 */
typedef int (*cpu_stop_fn_t)(void *arg);

#ifdef CONFIG_SMP

struct cpu_stop_work {
	struct list_head	list;		/* cpu_stopper->works */
	cpu_stop_fn_t		fn;
	void			*arg;
	struct cpu_stop_done	*done;
};

extern struct mutex stop_cpus_mutex;

int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
			 struct cpu_stop_work *work_buf);
int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);

#else	/* CONFIG_SMP */

#include <linux/workqueue.h>

struct cpu_stop_work {
	struct work_struct	work;
	cpu_stop_fn_t		fn;
	void			*arg;
};

static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
{
	int ret = -ENOENT;
	preempt_disable();
	if (cpu == smp_processor_id())
		ret = fn(arg);
	preempt_enable();
	return ret;
}

static void stop_one_cpu_nowait_workfn(struct work_struct *work)
{
	struct cpu_stop_work *stwork =
		container_of(work, struct cpu_stop_work, work);
	preempt_disable();
	stwork->fn(stwork->arg);
	preempt_enable();
}

static inline void stop_one_cpu_nowait(unsigned int cpu,
				       cpu_stop_fn_t fn, void *arg,
				       struct cpu_stop_work *work_buf)
{
	if (cpu == smp_processor_id()) {
		INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
		work_buf->fn = fn;
		work_buf->arg = arg;
		schedule_work(&work_buf->work);
	}
}

static inline int stop_cpus(const struct cpumask *cpumask,
			    cpu_stop_fn_t fn, void *arg)
{
	if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
		return stop_one_cpu(raw_smp_processor_id(), fn, arg);
	return -ENOENT;
}

static inline int try_stop_cpus(const struct cpumask *cpumask,
				cpu_stop_fn_t fn, void *arg)
{
	return stop_cpus(cpumask, fn, arg);
}

#endif	/* CONFIG_SMP */

/*
 * stop_machine "Bogolock": stop the entire machine, disable
 * interrupts.  This is a very heavy lock, which is equivalent to
 * grabbing every spinlock (and more).  So the "read" side to such a
 * lock is anything which disables preeempt.
 */
#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)

/**
 * stop_machine: freeze the machine on all CPUs and run this function
 * @fn: the function to run
 * @data: the data ptr for the @fn()
 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 *
 * Description: This causes a thread to be scheduled on every cpu,
 * each of which disables interrupts.  The result is that no one is
 * holding a spinlock or inside any other preempt-disabled region when
 * @fn() runs.
 *
 * This can be thought of as a very heavy write lock, equivalent to
 * grabbing every spinlock in the kernel. */
int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);

/**
 * __stop_machine: freeze the machine on all CPUs and run this function
 * @fn: the function to run
 * @data: the data ptr for the @fn
 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 *
 * Description: This is a special version of the above, which assumes cpus
 * won't come or go while it's being called.  Used by hotplug cpu.
 */
int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);

int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
				   const struct cpumask *cpus);

#else	 /* CONFIG_STOP_MACHINE && CONFIG_SMP */

static inline int __stop_machine(int (*fn)(void *), void *data,
				 const struct cpumask *cpus)
{
	unsigned long flags;
	int ret;
	local_irq_save(flags);
	ret = fn(data);
	local_irq_restore(flags);
	return ret;
}

static inline int stop_machine(int (*fn)(void *), void *data,
			       const struct cpumask *cpus)
{
	return __stop_machine(fn, data, cpus);
}

static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
						 const struct cpumask *cpus)
{
	return __stop_machine(fn, data, cpus);
}

#endif	/* CONFIG_STOP_MACHINE && CONFIG_SMP */
#endif	/* _LINUX_STOP_MACHINE */
OpenPOWER on IntegriCloud