1 #ifndef _LINUX_STOP_MACHINE
2 #define _LINUX_STOP_MACHINE
3
4 #include <linux/cpu.h>
5 #include <linux/cpumask.h>
6 #include <linux/list.h>
7 #include <asm/system.h>
8
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 */
19 typedef int (*cpu_stop_fn_t)(void *arg);
20
21 #ifdef CONFIG_SMP
22
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
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
stop_one_cpu(unsigned int cpu,cpu_stop_fn_t fn,void * arg)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
stop_one_cpu_nowait_workfn(struct work_struct * work)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
stop_one_cpu_nowait(unsigned int cpu,cpu_stop_fn_t fn,void * arg,struct cpu_stop_work * work_buf)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
stop_cpus(const struct cpumask * cpumask,cpu_stop_fn_t fn,void * arg)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
try_stop_cpus(const struct cpumask * cpumask,cpu_stop_fn_t fn,void * arg)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
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
97 * lock is anything which disables preeempt.
98 */
99 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
100
101 /**
102 * stop_machine: freeze the machine on all CPUs and run this function
103 * @fn: the function to run
104 * @data: the data ptr for the @fn()
105 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
106 *
107 * Description: This causes a thread to be scheduled on every cpu,
108 * each of which disables interrupts. The result is that no one is
109 * holding a spinlock or inside any other preempt-disabled region when
110 * @fn() runs.
111 *
112 * This can be thought of as a very heavy write lock, equivalent to
113 * grabbing every spinlock in the kernel. */
114 int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
115
116 /**
117 * __stop_machine: freeze the machine on all CPUs and run this function
118 * @fn: the function to run
119 * @data: the data ptr for the @fn
120 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
121 *
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.
124 */
125 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
126
127 #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
128
__stop_machine(int (* fn)(void *),void * data,const struct cpumask * cpus)129 static inline int __stop_machine(int (*fn)(void *), void *data,
130 const struct cpumask *cpus)
131 {
132 int ret;
133 local_irq_disable();
134 ret = fn(data);
135 local_irq_enable();
136 return ret;
137 }
138
stop_machine(int (* fn)(void *),void * data,const struct cpumask * cpus)139 static inline int stop_machine(int (*fn)(void *), void *data,
140 const struct cpumask *cpus)
141 {
142 return __stop_machine(fn, data, cpus);
143 }
144
145 #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
146 #endif /* _LINUX_STOP_MACHINE */
147