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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_STOP_MACHINE |
3 | #define _LINUX_STOP_MACHINE | |
1142d810 | 4 | |
1da177e4 | 5 | #include <linux/cpu.h> |
eeec4fad | 6 | #include <linux/cpumask.h> |
bb2eac66 | 7 | #include <linux/smp.h> |
1142d810 | 8 | #include <linux/list.h> |
1da177e4 | 9 | |
1142d810 TH |
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 | */ | |
1142d810 TH |
20 | typedef int (*cpu_stop_fn_t)(void *arg); |
21 | ||
bbf1bb3e TH |
22 | #ifdef CONFIG_SMP |
23 | ||
1142d810 TH |
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); | |
1be0bd77 | 32 | int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); |
1b034bd9 | 33 | bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, |
1142d810 TH |
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); | |
233e7f26 | 37 | void stop_machine_park(int cpu); |
c00166d8 | 38 | void stop_machine_unpark(int cpu); |
4ecf0a43 | 39 | void stop_machine_yield(const struct cpumask *cpumask); |
1142d810 | 40 | |
bbf1bb3e TH |
41 | #else /* CONFIG_SMP */ |
42 | ||
43 | #include <linux/workqueue.h> | |
44 | ||
45 | struct cpu_stop_work { | |
46 | struct work_struct work; | |
47 | cpu_stop_fn_t fn; | |
48 | void *arg; | |
49 | }; | |
50 | ||
51 | static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) | |
52 | { | |
53 | int ret = -ENOENT; | |
54 | preempt_disable(); | |
55 | if (cpu == smp_processor_id()) | |
56 | ret = fn(arg); | |
57 | preempt_enable(); | |
58 | return ret; | |
59 | } | |
60 | ||
61 | static void stop_one_cpu_nowait_workfn(struct work_struct *work) | |
62 | { | |
63 | struct cpu_stop_work *stwork = | |
64 | container_of(work, struct cpu_stop_work, work); | |
65 | preempt_disable(); | |
66 | stwork->fn(stwork->arg); | |
67 | preempt_enable(); | |
68 | } | |
69 | ||
1b034bd9 | 70 | static inline bool stop_one_cpu_nowait(unsigned int cpu, |
bbf1bb3e TH |
71 | cpu_stop_fn_t fn, void *arg, |
72 | struct cpu_stop_work *work_buf) | |
73 | { | |
74 | if (cpu == smp_processor_id()) { | |
75 | INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); | |
76 | work_buf->fn = fn; | |
77 | work_buf->arg = arg; | |
78 | schedule_work(&work_buf->work); | |
1b034bd9 | 79 | return true; |
bbf1bb3e | 80 | } |
1b034bd9 ON |
81 | |
82 | return false; | |
bbf1bb3e TH |
83 | } |
84 | ||
85 | static inline int stop_cpus(const struct cpumask *cpumask, | |
86 | cpu_stop_fn_t fn, void *arg) | |
87 | { | |
88 | if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) | |
89 | return stop_one_cpu(raw_smp_processor_id(), fn, arg); | |
90 | return -ENOENT; | |
91 | } | |
92 | ||
93 | static inline int try_stop_cpus(const struct cpumask *cpumask, | |
94 | cpu_stop_fn_t fn, void *arg) | |
95 | { | |
96 | return stop_cpus(cpumask, fn, arg); | |
97 | } | |
98 | ||
99 | #endif /* CONFIG_SMP */ | |
100 | ||
1142d810 TH |
101 | /* |
102 | * stop_machine "Bogolock": stop the entire machine, disable | |
103 | * interrupts. This is a very heavy lock, which is equivalent to | |
104 | * grabbing every spinlock (and more). So the "read" side to such a | |
1816315b | 105 | * lock is anything which disables preemption. |
1142d810 | 106 | */ |
86fffe4a | 107 | #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) |
1142d810 | 108 | |
1da177e4 | 109 | /** |
eeec4fad | 110 | * stop_machine: freeze the machine on all CPUs and run this function |
1da177e4 LT |
111 | * @fn: the function to run |
112 | * @data: the data ptr for the @fn() | |
eeec4fad | 113 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
1da177e4 | 114 | * |
ffdb5976 | 115 | * Description: This causes a thread to be scheduled on every cpu, |
25985edc | 116 | * each of which disables interrupts. The result is that no one is |
ffdb5976 RR |
117 | * holding a spinlock or inside any other preempt-disabled region when |
118 | * @fn() runs. | |
1da177e4 LT |
119 | * |
120 | * This can be thought of as a very heavy write lock, equivalent to | |
fe5595c0 SAS |
121 | * grabbing every spinlock in the kernel. |
122 | * | |
123 | * Protects against CPU hotplug. | |
124 | */ | |
9a301f22 | 125 | int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); |
1da177e4 | 126 | |
fe5595c0 SAS |
127 | /** |
128 | * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function | |
129 | * @fn: the function to run | |
130 | * @data: the data ptr for the @fn() | |
131 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) | |
132 | * | |
133 | * Same as above. Must be called from with in a cpus_read_lock() protected | |
134 | * region. Avoids nested calls to cpus_read_lock(). | |
135 | */ | |
136 | int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); | |
137 | ||
9a301f22 | 138 | int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, |
f740e6cd | 139 | const struct cpumask *cpus); |
86fffe4a | 140 | #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ |
1da177e4 | 141 | |
fe5595c0 SAS |
142 | static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, |
143 | const struct cpumask *cpus) | |
1da177e4 | 144 | { |
f740e6cd | 145 | unsigned long flags; |
1da177e4 | 146 | int ret; |
f740e6cd | 147 | local_irq_save(flags); |
1da177e4 | 148 | ret = fn(data); |
f740e6cd | 149 | local_irq_restore(flags); |
1da177e4 LT |
150 | return ret; |
151 | } | |
9ea09af3 | 152 | |
fe5595c0 SAS |
153 | static inline int stop_machine(cpu_stop_fn_t fn, void *data, |
154 | const struct cpumask *cpus) | |
155 | { | |
156 | return stop_machine_cpuslocked(fn, data, cpus); | |
157 | } | |
158 | ||
9a301f22 | 159 | static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, |
f740e6cd TH |
160 | const struct cpumask *cpus) |
161 | { | |
7eeb088e | 162 | return stop_machine(fn, data, cpus); |
f740e6cd TH |
163 | } |
164 | ||
86fffe4a | 165 | #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ |
bbf1bb3e | 166 | #endif /* _LINUX_STOP_MACHINE */ |