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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_STOP_MACHINE
2#define _LINUX_STOP_MACHINE
Tejun Heo1142d812010-05-06 18:49:20 +02003
Linus Torvalds1da177e2005-04-16 15:20:36 -07004#include <linux/cpu.h>
Rusty Russelleeec4fa2008-07-28 12:16:30 -05005#include <linux/cpumask.h>
Paul Gortmakerbb2eac62011-07-17 17:11:26 -04006#include <linux/smp.h>
Tejun Heo1142d812010-05-06 18:49:20 +02007#include <linux/list.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#include <asm/system.h>
9
Tejun Heo1142d812010-05-06 18:49:20 +020010/*
11 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
12 * monopolization mechanism. The caller can specify a non-sleeping
13 * function to be executed on a single or multiple cpus preempting all
14 * other processes and monopolizing those cpus until it finishes.
15 *
16 * Resources for this mechanism are preallocated when a cpu is brought
17 * up and requests are guaranteed to be served as long as the target
18 * cpus are online.
19 */
Tejun Heo1142d812010-05-06 18:49:20 +020020typedef int (*cpu_stop_fn_t)(void *arg);
21
Tejun Heobbf1bb32010-05-08 16:20:53 +020022#ifdef CONFIG_SMP
23
Tejun Heo1142d812010-05-06 18:49:20 +020024struct cpu_stop_work {
25 struct list_head list; /* cpu_stopper->works */
26 cpu_stop_fn_t fn;
27 void *arg;
28 struct cpu_stop_done *done;
29};
30
31int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
32void 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);
36
Tejun Heobbf1bb32010-05-08 16:20:53 +020037#else /* CONFIG_SMP */
38
39#include <linux/workqueue.h>
40
41struct cpu_stop_work {
42 struct work_struct work;
43 cpu_stop_fn_t fn;
44 void *arg;
45};
46
47static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
48{
49 int ret = -ENOENT;
50 preempt_disable();
51 if (cpu == smp_processor_id())
52 ret = fn(arg);
53 preempt_enable();
54 return ret;
55}
56
57static void stop_one_cpu_nowait_workfn(struct work_struct *work)
58{
59 struct cpu_stop_work *stwork =
60 container_of(work, struct cpu_stop_work, work);
61 preempt_disable();
62 stwork->fn(stwork->arg);
63 preempt_enable();
64}
65
66static inline void stop_one_cpu_nowait(unsigned int cpu,
67 cpu_stop_fn_t fn, void *arg,
68 struct cpu_stop_work *work_buf)
69{
70 if (cpu == smp_processor_id()) {
71 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
72 work_buf->fn = fn;
73 work_buf->arg = arg;
74 schedule_work(&work_buf->work);
75 }
76}
77
78static inline int stop_cpus(const struct cpumask *cpumask,
79 cpu_stop_fn_t fn, void *arg)
80{
81 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
82 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
83 return -ENOENT;
84}
85
86static inline int try_stop_cpus(const struct cpumask *cpumask,
87 cpu_stop_fn_t fn, void *arg)
88{
89 return stop_cpus(cpumask, fn, arg);
90}
91
92#endif /* CONFIG_SMP */
93
Tejun Heo1142d812010-05-06 18:49:20 +020094/*
95 * stop_machine "Bogolock": stop the entire machine, disable
96 * interrupts. This is a very heavy lock, which is equivalent to
97 * grabbing every spinlock (and more). So the "read" side to such a
Jonathan Neuschäfer18163152011-06-19 11:50:22 +020098 * lock is anything which disables preemption.
Tejun Heo1142d812010-05-06 18:49:20 +020099 */
Tejun Heobbf1bb32010-05-08 16:20:53 +0200100#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
Tejun Heo1142d812010-05-06 18:49:20 +0200101
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102/**
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500103 * stop_machine: freeze the machine on all CPUs and run this function
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 * @fn: the function to run
105 * @data: the data ptr for the @fn()
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500106 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 *
Rusty Russellffdb5972008-07-28 12:16:28 -0500108 * Description: This causes a thread to be scheduled on every cpu,
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300109 * each of which disables interrupts. The result is that no one is
Rusty Russellffdb5972008-07-28 12:16:28 -0500110 * holding a spinlock or inside any other preempt-disabled region when
111 * @fn() runs.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 *
113 * This can be thought of as a very heavy write lock, equivalent to
114 * grabbing every spinlock in the kernel. */
Rusty Russell41c7bb92009-01-01 10:12:28 +1030115int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117/**
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500118 * __stop_machine: freeze the machine on all CPUs and run this function
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 * @fn: the function to run
120 * @data: the data ptr for the @fn
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500121 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 *
Rusty Russellffdb5972008-07-28 12:16:28 -0500123 * Description: This is a special version of the above, which assumes cpus
124 * won't come or go while it's being called. Used by hotplug cpu.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 */
Rusty Russell41c7bb92009-01-01 10:12:28 +1030126int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
Heiko Carstens9ea09af2008-12-22 12:36:30 +0100127
Tejun Heof740e6cd2011-06-23 11:19:28 -0700128int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
129 const struct cpumask *cpus);
130
Tejun Heobbf1bb32010-05-08 16:20:53 +0200131#else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
Masami Hiramatsu087a4eb2010-10-14 12:10:30 +0900133static inline int __stop_machine(int (*fn)(void *), void *data,
134 const struct cpumask *cpus)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
Tejun Heof740e6cd2011-06-23 11:19:28 -0700136 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 int ret;
Tejun Heof740e6cd2011-06-23 11:19:28 -0700138 local_irq_save(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 ret = fn(data);
Tejun Heof740e6cd2011-06-23 11:19:28 -0700140 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 return ret;
142}
Heiko Carstens9ea09af2008-12-22 12:36:30 +0100143
Masami Hiramatsu087a4eb2010-10-14 12:10:30 +0900144static inline int stop_machine(int (*fn)(void *), void *data,
145 const struct cpumask *cpus)
146{
147 return __stop_machine(fn, data, cpus);
148}
149
Tejun Heof740e6cd2011-06-23 11:19:28 -0700150static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
151 const struct cpumask *cpus)
152{
153 return __stop_machine(fn, data, cpus);
154}
155
Tejun Heobbf1bb32010-05-08 16:20:53 +0200156#endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
157#endif /* _LINUX_STOP_MACHINE */