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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
Tejun Heo1142d812010-05-06 18:49:20 +02009/*
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 */
Tejun Heo1142d812010-05-06 18:49:20 +020019typedef int (*cpu_stop_fn_t)(void *arg);
20
Tejun Heobbf1bb32010-05-08 16:20:53 +020021#ifdef CONFIG_SMP
22
Tejun Heo1142d812010-05-06 18:49:20 +020023struct 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);
31void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
32 struct cpu_stop_work *work_buf);
33int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
34int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
35
Tejun Heobbf1bb32010-05-08 16:20:53 +020036#else /* CONFIG_SMP */
37
38#include <linux/workqueue.h>
39
40struct cpu_stop_work {
41 struct work_struct work;
42 cpu_stop_fn_t fn;
43 void *arg;
44};
45
46static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
47{
48 int ret = -ENOENT;
49 preempt_disable();
50 if (cpu == smp_processor_id())
51 ret = fn(arg);
52 preempt_enable();
53 return ret;
54}
55
56static void stop_one_cpu_nowait_workfn(struct work_struct *work)
57{
58 struct cpu_stop_work *stwork =
59 container_of(work, struct cpu_stop_work, work);
60 preempt_disable();
61 stwork->fn(stwork->arg);
62 preempt_enable();
63}
64
65static inline void stop_one_cpu_nowait(unsigned int cpu,
66 cpu_stop_fn_t fn, void *arg,
67 struct cpu_stop_work *work_buf)
68{
69 if (cpu == smp_processor_id()) {
70 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
71 work_buf->fn = fn;
72 work_buf->arg = arg;
73 schedule_work(&work_buf->work);
74 }
75}
76
77static inline int stop_cpus(const struct cpumask *cpumask,
78 cpu_stop_fn_t fn, void *arg)
79{
80 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
81 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
82 return -ENOENT;
83}
84
85static inline int try_stop_cpus(const struct cpumask *cpumask,
86 cpu_stop_fn_t fn, void *arg)
87{
88 return stop_cpus(cpumask, fn, arg);
89}
90
91#endif /* CONFIG_SMP */
92
Tejun Heo1142d812010-05-06 18:49:20 +020093/*
94 * stop_machine "Bogolock": stop the entire machine, disable
95 * interrupts. This is a very heavy lock, which is equivalent to
96 * grabbing every spinlock (and more). So the "read" side to such a
Jonathan Neuschäfer18163152011-06-19 11:50:22 +020097 * lock is anything which disables preemption.
Tejun Heo1142d812010-05-06 18:49:20 +020098 */
Tejun Heobbf1bb32010-05-08 16:20:53 +020099#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
Tejun Heo1142d812010-05-06 18:49:20 +0200100
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101/**
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500102 * stop_machine: freeze the machine on all CPUs and run this function
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 * @fn: the function to run
104 * @data: the data ptr for the @fn()
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500105 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 *
Rusty Russellffdb5972008-07-28 12:16:28 -0500107 * Description: This causes a thread to be scheduled on every cpu,
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300108 * each of which disables interrupts. The result is that no one is
Rusty Russellffdb5972008-07-28 12:16:28 -0500109 * holding a spinlock or inside any other preempt-disabled region when
110 * @fn() runs.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 *
112 * This can be thought of as a very heavy write lock, equivalent to
113 * grabbing every spinlock in the kernel. */
Rusty Russell41c7bb92009-01-01 10:12:28 +1030114int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116/**
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500117 * __stop_machine: freeze the machine on all CPUs and run this function
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 * @fn: the function to run
119 * @data: the data ptr for the @fn
Rusty Russelleeec4fa2008-07-28 12:16:30 -0500120 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 *
Rusty Russellffdb5972008-07-28 12:16:28 -0500122 * Description: This is a special version of the above, which assumes cpus
123 * won't come or go while it's being called. Used by hotplug cpu.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 */
Rusty Russell41c7bb92009-01-01 10:12:28 +1030125int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
Heiko Carstens9ea09af2008-12-22 12:36:30 +0100126
Tejun Heof740e6cd2011-06-23 11:19:28 -0700127int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
128 const struct cpumask *cpus);
129
Tejun Heobbf1bb32010-05-08 16:20:53 +0200130#else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
Masami Hiramatsu087a4eb2010-10-14 12:10:30 +0900132static inline int __stop_machine(int (*fn)(void *), void *data,
133 const struct cpumask *cpus)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134{
Tejun Heof740e6cd2011-06-23 11:19:28 -0700135 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 int ret;
Tejun Heof740e6cd2011-06-23 11:19:28 -0700137 local_irq_save(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 ret = fn(data);
Tejun Heof740e6cd2011-06-23 11:19:28 -0700139 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 return ret;
141}
Heiko Carstens9ea09af2008-12-22 12:36:30 +0100142
Masami Hiramatsu087a4eb2010-10-14 12:10:30 +0900143static inline int stop_machine(int (*fn)(void *), void *data,
144 const struct cpumask *cpus)
145{
146 return __stop_machine(fn, data, cpus);
147}
148
Tejun Heof740e6cd2011-06-23 11:19:28 -0700149static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
150 const struct cpumask *cpus)
151{
152 return __stop_machine(fn, data, cpus);
153}
154
Tejun Heobbf1bb32010-05-08 16:20:53 +0200155#endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
156#endif /* _LINUX_STOP_MACHINE */