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1da177e4 LT |
1 | #ifndef _LINUX_STOP_MACHINE |
2 | #define _LINUX_STOP_MACHINE | |
1142d810 | 3 | |
1da177e4 | 4 | #include <linux/cpu.h> |
eeec4fad | 5 | #include <linux/cpumask.h> |
bb2eac66 | 6 | #include <linux/smp.h> |
1142d810 | 7 | #include <linux/list.h> |
1da177e4 | 8 | |
1142d810 TH |
9 | /* |
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 | */ | |
1142d810 TH |
19 | typedef int (*cpu_stop_fn_t)(void *arg); |
20 | ||
bbf1bb3e TH |
21 | #ifdef CONFIG_SMP |
22 | ||
1142d810 TH |
23 | struct 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 | ||
30 | int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); | |
31 | void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, | |
32 | struct cpu_stop_work *work_buf); | |
33 | int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); | |
34 | int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); | |
35 | ||
bbf1bb3e TH |
36 | #else /* CONFIG_SMP */ |
37 | ||
38 | #include <linux/workqueue.h> | |
39 | ||
40 | struct cpu_stop_work { | |
41 | struct work_struct work; | |
42 | cpu_stop_fn_t fn; | |
43 | void *arg; | |
44 | }; | |
45 | ||
46 | static 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 | ||
56 | static 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 | ||
65 | static 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 | ||
77 | static 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 | ||
85 | static 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 | ||
1142d810 TH |
93 | /* |
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 | |
1816315b | 97 | * lock is anything which disables preemption. |
1142d810 | 98 | */ |
bbf1bb3e | 99 | #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP) |
1142d810 | 100 | |
1da177e4 | 101 | /** |
eeec4fad | 102 | * stop_machine: freeze the machine on all CPUs and run this function |
1da177e4 LT |
103 | * @fn: the function to run |
104 | * @data: the data ptr for the @fn() | |
eeec4fad | 105 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
1da177e4 | 106 | * |
ffdb5976 | 107 | * Description: This causes a thread to be scheduled on every cpu, |
25985edc | 108 | * each of which disables interrupts. The result is that no one is |
ffdb5976 RR |
109 | * holding a spinlock or inside any other preempt-disabled region when |
110 | * @fn() runs. | |
1da177e4 LT |
111 | * |
112 | * This can be thought of as a very heavy write lock, equivalent to | |
113 | * grabbing every spinlock in the kernel. */ | |
41c7bb95 | 114 | int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); |
1da177e4 LT |
115 | |
116 | /** | |
eeec4fad | 117 | * __stop_machine: freeze the machine on all CPUs and run this function |
1da177e4 LT |
118 | * @fn: the function to run |
119 | * @data: the data ptr for the @fn | |
eeec4fad | 120 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
1da177e4 | 121 | * |
ffdb5976 RR |
122 | * 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. | |
1da177e4 | 124 | */ |
41c7bb95 | 125 | int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); |
9ea09af3 | 126 | |
f740e6cd TH |
127 | int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, |
128 | const struct cpumask *cpus); | |
129 | ||
bbf1bb3e | 130 | #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ |
1da177e4 | 131 | |
087a4eb5 MH |
132 | static inline int __stop_machine(int (*fn)(void *), void *data, |
133 | const struct cpumask *cpus) | |
1da177e4 | 134 | { |
f740e6cd | 135 | unsigned long flags; |
1da177e4 | 136 | int ret; |
f740e6cd | 137 | local_irq_save(flags); |
1da177e4 | 138 | ret = fn(data); |
f740e6cd | 139 | local_irq_restore(flags); |
1da177e4 LT |
140 | return ret; |
141 | } | |
9ea09af3 | 142 | |
087a4eb5 MH |
143 | static inline int stop_machine(int (*fn)(void *), void *data, |
144 | const struct cpumask *cpus) | |
145 | { | |
146 | return __stop_machine(fn, data, cpus); | |
147 | } | |
148 | ||
f740e6cd TH |
149 | static 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 | ||
bbf1bb3e TH |
155 | #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */ |
156 | #endif /* _LINUX_STOP_MACHINE */ |