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