1 #ifndef _LINUX_STOP_MACHINE
2 #define _LINUX_STOP_MACHINE
3
4 #include <linux/cpu.h>
5 #include <linux/cpumask.h>
6 #include <linux/smp.h>
7 #include <linux/list.h>
8 #include <asm/system.h>
9
10 /*
11 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
12 * monopolization mechanism. The caller can specify a non-sleeping
13 * function to be executed on a single or multiple cpus preempting all
14 * other processes and monopolizing those cpus until it finishes.
15 *
16 * Resources for this mechanism are preallocated when a cpu is brought
17 * up and requests are guaranteed to be served as long as the target
18 * cpus are online.
19 */
20 typedef int (*cpu_stop_fn_t)(void *arg);
21
22 #ifdef CONFIG_SMP
23
24 struct cpu_stop_work {
25 struct list_head list; /* cpu_stopper->works */
26 cpu_stop_fn_t fn;
27 void *arg;
28 struct cpu_stop_done *done;
29 };
30
31 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
32 void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
33 struct cpu_stop_work *work_buf);
34 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
35 int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
36
37 #else /* CONFIG_SMP */
38
39 #include <linux/workqueue.h>
40
41 struct cpu_stop_work {
42 struct work_struct work;
43 cpu_stop_fn_t fn;
44 void *arg;
45 };
46
stop_one_cpu(unsigned int cpu,cpu_stop_fn_t fn,void * arg)47 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
48 {
49 int ret = -ENOENT;
50 preempt_disable();
51 if (cpu == smp_processor_id())
52 ret = fn(arg);
53 preempt_enable();
54 return ret;
55 }
56
stop_one_cpu_nowait_workfn(struct work_struct * work)57 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
58 {
59 struct cpu_stop_work *stwork =
60 container_of(work, struct cpu_stop_work, work);
61 preempt_disable();
62 stwork->fn(stwork->arg);
63 preempt_enable();
64 }
65
stop_one_cpu_nowait(unsigned int cpu,cpu_stop_fn_t fn,void * arg,struct cpu_stop_work * work_buf)66 static inline void stop_one_cpu_nowait(unsigned int cpu,
67 cpu_stop_fn_t fn, void *arg,
68 struct cpu_stop_work *work_buf)
69 {
70 if (cpu == smp_processor_id()) {
71 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
72 work_buf->fn = fn;
73 work_buf->arg = arg;
74 schedule_work(&work_buf->work);
75 }
76 }
77
stop_cpus(const struct cpumask * cpumask,cpu_stop_fn_t fn,void * arg)78 static inline int stop_cpus(const struct cpumask *cpumask,
79 cpu_stop_fn_t fn, void *arg)
80 {
81 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
82 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
83 return -ENOENT;
84 }
85
try_stop_cpus(const struct cpumask * cpumask,cpu_stop_fn_t fn,void * arg)86 static inline int try_stop_cpus(const struct cpumask *cpumask,
87 cpu_stop_fn_t fn, void *arg)
88 {
89 return stop_cpus(cpumask, fn, arg);
90 }
91
92 #endif /* CONFIG_SMP */
93
94 /*
95 * stop_machine "Bogolock": stop the entire machine, disable
96 * interrupts. This is a very heavy lock, which is equivalent to
97 * grabbing every spinlock (and more). So the "read" side to such a
98 * lock is anything which disables preemption.
99 */
100 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
101
102 /**
103 * stop_machine: freeze the machine on all CPUs and run this function
104 * @fn: the function to run
105 * @data: the data ptr for the @fn()
106 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
107 *
108 * Description: This causes a thread to be scheduled on every cpu,
109 * each of which disables interrupts. The result is that no one is
110 * holding a spinlock or inside any other preempt-disabled region when
111 * @fn() runs.
112 *
113 * This can be thought of as a very heavy write lock, equivalent to
114 * grabbing every spinlock in the kernel. */
115 int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
116
117 /**
118 * __stop_machine: freeze the machine on all CPUs and run this function
119 * @fn: the function to run
120 * @data: the data ptr for the @fn
121 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
122 *
123 * Description: This is a special version of the above, which assumes cpus
124 * won't come or go while it's being called. Used by hotplug cpu.
125 */
126 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
127
128 int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
129 const struct cpumask *cpus);
130
131 #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
132
__stop_machine(int (* fn)(void *),void * data,const struct cpumask * cpus)133 static inline int __stop_machine(int (*fn)(void *), void *data,
134 const struct cpumask *cpus)
135 {
136 unsigned long flags;
137 int ret;
138 local_irq_save(flags);
139 ret = fn(data);
140 local_irq_restore(flags);
141 return ret;
142 }
143
stop_machine(int (* fn)(void *),void * data,const struct cpumask * cpus)144 static inline int stop_machine(int (*fn)(void *), void *data,
145 const struct cpumask *cpus)
146 {
147 return __stop_machine(fn, data, cpus);
148 }
149
stop_machine_from_inactive_cpu(int (* fn)(void *),void * data,const struct cpumask * cpus)150 static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
151 const struct cpumask *cpus)
152 {
153 return __stop_machine(fn, data, cpus);
154 }
155
156 #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
157 #endif /* _LINUX_STOP_MACHINE */
158