Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _LINUX_STOP_MACHINE
3 : #define _LINUX_STOP_MACHINE
4 :
5 : #include <linux/cpu.h>
6 : #include <linux/cpumask.h>
7 : #include <linux/smp.h>
8 : #include <linux/list.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 : unsigned long caller;
28 : void *arg;
29 : struct cpu_stop_done *done;
30 : };
31 :
32 : int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
33 : int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg);
34 : bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
35 : struct cpu_stop_work *work_buf);
36 : void stop_machine_park(int cpu);
37 : void stop_machine_unpark(int cpu);
38 : void stop_machine_yield(const struct cpumask *cpumask);
39 :
40 : extern void print_stop_info(const char *log_lvl, struct task_struct *task);
41 :
42 : #else /* CONFIG_SMP */
43 :
44 : #include <linux/workqueue.h>
45 :
46 : struct cpu_stop_work {
47 : struct work_struct work;
48 : cpu_stop_fn_t fn;
49 : void *arg;
50 : };
51 :
52 : static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
53 : {
54 : int ret = -ENOENT;
55 : preempt_disable();
56 : if (cpu == smp_processor_id())
57 : ret = fn(arg);
58 : preempt_enable();
59 : return ret;
60 : }
61 :
62 : static void stop_one_cpu_nowait_workfn(struct work_struct *work)
63 : {
64 : struct cpu_stop_work *stwork =
65 : container_of(work, struct cpu_stop_work, work);
66 : preempt_disable();
67 : stwork->fn(stwork->arg);
68 : preempt_enable();
69 : }
70 :
71 : static inline bool stop_one_cpu_nowait(unsigned int cpu,
72 : cpu_stop_fn_t fn, void *arg,
73 : struct cpu_stop_work *work_buf)
74 : {
75 : if (cpu == smp_processor_id()) {
76 : INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
77 : work_buf->fn = fn;
78 : work_buf->arg = arg;
79 : schedule_work(&work_buf->work);
80 : return true;
81 : }
82 :
83 : return false;
84 : }
85 :
86 : static inline void print_stop_info(const char *log_lvl, struct task_struct *task) { }
87 :
88 : #endif /* CONFIG_SMP */
89 :
90 : /*
91 : * stop_machine "Bogolock": stop the entire machine, disable
92 : * interrupts. This is a very heavy lock, which is equivalent to
93 : * grabbing every spinlock (and more). So the "read" side to such a
94 : * lock is anything which disables preemption.
95 : */
96 : #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
97 :
98 : /**
99 : * stop_machine: freeze the machine on all CPUs and run this function
100 : * @fn: the function to run
101 : * @data: the data ptr for the @fn()
102 : * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
103 : *
104 : * Description: This causes a thread to be scheduled on every cpu,
105 : * each of which disables interrupts. The result is that no one is
106 : * holding a spinlock or inside any other preempt-disabled region when
107 : * @fn() runs.
108 : *
109 : * This can be thought of as a very heavy write lock, equivalent to
110 : * grabbing every spinlock in the kernel.
111 : *
112 : * Protects against CPU hotplug.
113 : */
114 : int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
115 :
116 : /**
117 : * stop_machine_cpuslocked: 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 : * Same as above. Must be called from with in a cpus_read_lock() protected
123 : * region. Avoids nested calls to cpus_read_lock().
124 : */
125 : int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
126 :
127 : /**
128 : * stop_core_cpuslocked: - stop all threads on just one core
129 : * @cpu: any cpu in the targeted core
130 : * @fn: the function to run
131 : * @data: the data ptr for @fn()
132 : *
133 : * Same as above, but instead of every CPU, only the logical CPUs of a
134 : * single core are affected.
135 : *
136 : * Context: Must be called from within a cpus_read_lock() protected region.
137 : *
138 : * Return: 0 if all executions of @fn returned 0, any non zero return
139 : * value if any returned non zero.
140 : */
141 : int stop_core_cpuslocked(unsigned int cpu, cpu_stop_fn_t fn, void *data);
142 :
143 : int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
144 : const struct cpumask *cpus);
145 : #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
146 :
147 : static __always_inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,
148 : const struct cpumask *cpus)
149 : {
150 : unsigned long flags;
151 : int ret;
152 1 : local_irq_save(flags);
153 1 : ret = fn(data);
154 1 : local_irq_restore(flags);
155 : return ret;
156 : }
157 :
158 : static __always_inline int
159 : stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
160 : {
161 1 : return stop_machine_cpuslocked(fn, data, cpus);
162 : }
163 :
164 : static __always_inline int
165 : stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
166 : const struct cpumask *cpus)
167 : {
168 : return stop_machine(fn, data, cpus);
169 : }
170 :
171 : #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
172 : #endif /* _LINUX_STOP_MACHINE */
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