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-rw-r--r--kernel/power/smp.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/kernel/power/smp.c b/kernel/power/smp.c
new file mode 100644
index 000000000000..7fa7f6e2b7fb
--- /dev/null
+++ b/kernel/power/smp.c
@@ -0,0 +1,85 @@
1/*
2 * drivers/power/smp.c - Functions for stopping other CPUs.
3 *
4 * Copyright 2004 Pavel Machek <pavel@suse.cz>
5 * Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz>
6 *
7 * This file is released under the GPLv2.
8 */
9
10#undef DEBUG
11
12#include <linux/smp_lock.h>
13#include <linux/interrupt.h>
14#include <linux/suspend.h>
15#include <linux/module.h>
16#include <asm/atomic.h>
17#include <asm/tlbflush.h>
18
19static atomic_t cpu_counter, freeze;
20
21
22static void smp_pause(void * data)
23{
24 struct saved_context ctxt;
25 __save_processor_state(&ctxt);
26 printk("Sleeping in:\n");
27 dump_stack();
28 atomic_inc(&cpu_counter);
29 while (atomic_read(&freeze)) {
30 /* FIXME: restore takes place at random piece inside this.
31 This should probably be written in assembly, and
32 preserve general-purpose registers, too
33
34 What about stack? We may need to move to new stack here.
35
36 This should better be ran with interrupts disabled.
37 */
38 cpu_relax();
39 barrier();
40 }
41 atomic_dec(&cpu_counter);
42 __restore_processor_state(&ctxt);
43}
44
45static cpumask_t oldmask;
46
47void disable_nonboot_cpus(void)
48{
49 printk("Freezing CPUs (at %d)", smp_processor_id());
50 oldmask = current->cpus_allowed;
51 set_cpus_allowed(current, cpumask_of_cpu(0));
52 current->state = TASK_INTERRUPTIBLE;
53 schedule_timeout(HZ);
54 printk("...");
55 BUG_ON(smp_processor_id() != 0);
56
57 /* FIXME: for this to work, all the CPUs must be running
58 * "idle" thread (or we deadlock). Is that guaranteed? */
59
60 atomic_set(&cpu_counter, 0);
61 atomic_set(&freeze, 1);
62 smp_call_function(smp_pause, NULL, 0, 0);
63 while (atomic_read(&cpu_counter) < (num_online_cpus() - 1)) {
64 cpu_relax();
65 barrier();
66 }
67 printk("ok\n");
68}
69
70void enable_nonboot_cpus(void)
71{
72 printk("Restarting CPUs");
73 atomic_set(&freeze, 0);
74 while (atomic_read(&cpu_counter)) {
75 cpu_relax();
76 barrier();
77 }
78 printk("...");
79 set_cpus_allowed(current, oldmask);
80 schedule();
81 printk("ok\n");
82
83}
84
85