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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_STOP_MACHINE
2#define _LINUX_STOP_MACHINE
3/* "Bogolock": stop the entire machine, disable interrupts. This is a
4 very heavy lock, which is equivalent to grabbing every spinlock
5 (and more). So the "read" side to such a lock is anything which
6 diables preeempt. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/cpu.h>
8#include <asm/system.h>
9
10#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
11/**
12 * stop_machine_run: freeze the machine on all CPUs and run this function
13 * @fn: the function to run
14 * @data: the data ptr for the @fn()
15 * @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS.
16 *
17 * Description: This causes a thread to be scheduled on every other cpu,
18 * each of which disables interrupts, and finally interrupts are disabled
19 * on the current CPU. The result is that noone is holding a spinlock
20 * or inside any other preempt-disabled region when @fn() runs.
21 *
22 * This can be thought of as a very heavy write lock, equivalent to
23 * grabbing every spinlock in the kernel. */
24int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
25
26/**
27 * __stop_machine_run: freeze the machine on all CPUs and run this function
28 * @fn: the function to run
29 * @data: the data ptr for the @fn
30 * @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
31 *
32 * Description: This is a special version of the above, which returns the
33 * thread which has run @fn(): kthread_stop will return the return value
34 * of @fn(). Used by hotplug cpu.
35 */
36struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
37 unsigned int cpu);
38
39#else
40
41static inline int stop_machine_run(int (*fn)(void *), void *data,
42 unsigned int cpu)
43{
44 int ret;
45 local_irq_disable();
46 ret = fn(data);
47 local_irq_enable();
48 return ret;
49}
50#endif /* CONFIG_SMP */
51#endif /* _LINUX_STOP_MACHINE */