1 #ifndef _LINUX_STOP_MACHINE
2 #define _LINUX_STOP_MACHINE
5 #include <linux/cpumask.h>
7 #include <linux/list.h>
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.
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
19 typedef int (*cpu_stop_fn_t)(void *arg);
23 struct cpu_stop_work {
24 struct list_head list; /* cpu_stopper->works */
27 struct cpu_stop_done *done;
30 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
31 int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, 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 void stop_machine_park(int cpu);
37 void stop_machine_unpark(int cpu);
39 #else /* CONFIG_SMP */
41 #include <linux/workqueue.h>
43 struct cpu_stop_work {
44 struct work_struct work;
49 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
53 if (cpu == smp_processor_id())
59 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
61 struct cpu_stop_work *stwork =
62 container_of(work, struct cpu_stop_work, work);
64 stwork->fn(stwork->arg);
68 static inline void stop_one_cpu_nowait(unsigned int cpu,
69 cpu_stop_fn_t fn, void *arg,
70 struct cpu_stop_work *work_buf)
72 if (cpu == smp_processor_id()) {
73 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
76 schedule_work(&work_buf->work);
80 static inline int stop_cpus(const struct cpumask *cpumask,
81 cpu_stop_fn_t fn, void *arg)
83 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
84 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
88 static inline int try_stop_cpus(const struct cpumask *cpumask,
89 cpu_stop_fn_t fn, void *arg)
91 return stop_cpus(cpumask, fn, arg);
94 #endif /* CONFIG_SMP */
97 * stop_machine "Bogolock": stop the entire machine, disable
98 * interrupts. This is a very heavy lock, which is equivalent to
99 * grabbing every spinlock (and more). So the "read" side to such a
100 * lock is anything which disables preemption.
102 #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
105 * stop_machine: freeze the machine on all CPUs and run this function
106 * @fn: the function to run
107 * @data: the data ptr for the @fn()
108 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
110 * Description: This causes a thread to be scheduled on every cpu,
111 * each of which disables interrupts. The result is that no one is
112 * holding a spinlock or inside any other preempt-disabled region when
115 * This can be thought of as a very heavy write lock, equivalent to
116 * grabbing every spinlock in the kernel. */
117 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
119 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
120 const struct cpumask *cpus);
121 #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
123 static inline int stop_machine(cpu_stop_fn_t fn, void *data,
124 const struct cpumask *cpus)
128 local_irq_save(flags);
130 local_irq_restore(flags);
134 static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
135 const struct cpumask *cpus)
137 return stop_machine(fn, data, cpus);
140 #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
141 #endif /* _LINUX_STOP_MACHINE */