1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_STOP_MACHINE
3 #define _LINUX_STOP_MACHINE
6 #include <linux/cpumask.h>
8 #include <linux/list.h>
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.
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
20 typedef int (*cpu_stop_fn_t
)(void *arg
);
24 struct cpu_stop_work
{
25 struct list_head list
; /* cpu_stopper->works */
28 struct cpu_stop_done
*done
;
31 int stop_one_cpu(unsigned int cpu
, cpu_stop_fn_t fn
, void *arg
);
32 int stop_two_cpus(unsigned int cpu1
, unsigned int cpu2
, cpu_stop_fn_t fn
, void *arg
);
33 bool stop_one_cpu_nowait(unsigned int cpu
, cpu_stop_fn_t fn
, void *arg
,
34 struct cpu_stop_work
*work_buf
);
35 int stop_cpus(const struct cpumask
*cpumask
, cpu_stop_fn_t fn
, void *arg
);
36 int try_stop_cpus(const struct cpumask
*cpumask
, cpu_stop_fn_t fn
, void *arg
);
37 void stop_machine_park(int cpu
);
38 void stop_machine_unpark(int cpu
);
40 #else /* CONFIG_SMP */
42 #include <linux/workqueue.h>
44 struct cpu_stop_work
{
45 struct work_struct work
;
50 static inline int stop_one_cpu(unsigned int cpu
, cpu_stop_fn_t fn
, void *arg
)
54 if (cpu
== smp_processor_id())
60 static void stop_one_cpu_nowait_workfn(struct work_struct
*work
)
62 struct cpu_stop_work
*stwork
=
63 container_of(work
, struct cpu_stop_work
, work
);
65 stwork
->fn(stwork
->arg
);
69 static inline bool stop_one_cpu_nowait(unsigned int cpu
,
70 cpu_stop_fn_t fn
, void *arg
,
71 struct cpu_stop_work
*work_buf
)
73 if (cpu
== smp_processor_id()) {
74 INIT_WORK(&work_buf
->work
, stop_one_cpu_nowait_workfn
);
77 schedule_work(&work_buf
->work
);
84 static inline int stop_cpus(const struct cpumask
*cpumask
,
85 cpu_stop_fn_t fn
, void *arg
)
87 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask
))
88 return stop_one_cpu(raw_smp_processor_id(), fn
, arg
);
92 static inline int try_stop_cpus(const struct cpumask
*cpumask
,
93 cpu_stop_fn_t fn
, void *arg
)
95 return stop_cpus(cpumask
, fn
, arg
);
98 #endif /* CONFIG_SMP */
101 * stop_machine "Bogolock": stop the entire machine, disable
102 * interrupts. This is a very heavy lock, which is equivalent to
103 * grabbing every spinlock (and more). So the "read" side to such a
104 * lock is anything which disables preemption.
106 #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
109 * stop_machine: freeze the machine on all CPUs and run this function
110 * @fn: the function to run
111 * @data: the data ptr for the @fn()
112 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
114 * Description: This causes a thread to be scheduled on every cpu,
115 * each of which disables interrupts. The result is that no one is
116 * holding a spinlock or inside any other preempt-disabled region when
119 * This can be thought of as a very heavy write lock, equivalent to
120 * grabbing every spinlock in the kernel.
122 * Protects against CPU hotplug.
124 int stop_machine(cpu_stop_fn_t fn
, void *data
, const struct cpumask
*cpus
);
127 * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function
128 * @fn: the function to run
129 * @data: the data ptr for the @fn()
130 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
132 * Same as above. Must be called from with in a cpus_read_lock() protected
133 * region. Avoids nested calls to cpus_read_lock().
135 int stop_machine_cpuslocked(cpu_stop_fn_t fn
, void *data
, const struct cpumask
*cpus
);
137 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn
, void *data
,
138 const struct cpumask
*cpus
);
139 #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
141 static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn
, void *data
,
142 const struct cpumask
*cpus
)
146 local_irq_save(flags
);
148 local_irq_restore(flags
);
152 static inline int stop_machine(cpu_stop_fn_t fn
, void *data
,
153 const struct cpumask
*cpus
)
155 return stop_machine_cpuslocked(fn
, data
, cpus
);
158 static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn
, void *data
,
159 const struct cpumask
*cpus
)
161 return stop_machine(fn
, data
, cpus
);
164 #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
165 #endif /* _LINUX_STOP_MACHINE */