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 | local_irq_save(flags); |
153 | ret = fn(data); |
154 | 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 | 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 */ |
173 | |