| 1 | #ifndef _LINUX_STOP_MACHINE
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| 2 | #define _LINUX_STOP_MACHINE
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| 3 |
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| 4 | #include <linux/cpu.h>
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| 5 | #include <linux/cpumask.h>
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| 6 | #include <linux/smp.h>
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| 7 | #include <linux/list.h>
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| 8 |
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| 9 | |
| 10 | * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
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| 11 | * monopolization mechanism. The caller can specify a non-sleeping
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| 12 | * function to be executed on a single or multiple cpus preempting all
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| 13 | * other processes and monopolizing those cpus until it finishes.
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| 14 | *
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| 15 | * Resources for this mechanism are preallocated when a cpu is brought
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| 16 | * up and requests are guaranteed to be served as long as the target
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| 17 | * cpus are online.
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| 18 |
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| 19 | typedef int (*cpu_stop_fn_t)(void *arg);
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| 20 |
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| 21 | #ifdef CONFIG_SMP
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| 22 |
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| 23 | struct cpu_stop_work {
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| 24 | struct list_head list;
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| 25 | cpu_stop_fn_t fn;
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| 26 | void *arg;
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| 27 | struct cpu_stop_done *done;
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| 28 | };
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| 29 |
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| 30 | int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
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| 31 | void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
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| 32 | struct cpu_stop_work *work_buf);
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| 33 | int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
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| 34 | int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
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| 35 |
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| 36 | #else
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| 37 |
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| 38 | #include <linux/workqueue.h>
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| 39 |
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| 40 | struct cpu_stop_work {
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| 41 | struct work_struct work;
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| 42 | cpu_stop_fn_t fn;
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| 43 | void *arg;
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| 44 | };
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| 45 |
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| 46 | static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
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| 47 | {
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| 48 | int ret = -ENOENT;
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| 49 | preempt_disable();
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| 50 | if (cpu == smp_processor_id())
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| 51 | ret = fn(arg);
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| 52 | preempt_enable();
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| 53 | return ret;
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| 54 | }
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| 55 |
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| 56 | static void stop_one_cpu_nowait_workfn(struct work_struct *work)
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| 57 | {
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| 58 | struct cpu_stop_work *stwork =
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| 59 | container_of(work, struct cpu_stop_work, work);
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| 60 | preempt_disable();
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| 61 | stwork->fn(stwork->arg);
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| 62 | preempt_enable();
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| 63 | }
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| 64 |
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| 65 | static inline void stop_one_cpu_nowait(unsigned int cpu,
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| 66 | cpu_stop_fn_t fn, void *arg,
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| 67 | struct cpu_stop_work *work_buf)
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| 68 | {
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| 69 | if (cpu == smp_processor_id()) {
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| 70 | INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
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| 71 | work_buf->fn = fn;
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| 72 | work_buf->arg = arg;
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| 73 | schedule_work(&work_buf->work);
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| 74 | }
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| 75 | }
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| 76 |
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| 77 | static inline int stop_cpus(const struct cpumask *cpumask,
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| 78 | cpu_stop_fn_t fn, void *arg)
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| 79 | {
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| 80 | if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
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| 81 | return stop_one_cpu(raw_smp_processor_id(), fn, arg);
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| 82 | return -ENOENT;
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| 83 | }
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| 84 |
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| 85 | static inline int try_stop_cpus(const struct cpumask *cpumask,
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| 86 | cpu_stop_fn_t fn, void *arg)
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| 87 | {
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| 88 | return stop_cpus(cpumask, fn, arg);
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| 89 | }
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| 90 |
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| 91 | #endif
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| 92 |
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| 93 | |
| 94 | * stop_machine "Bogolock": stop the entire machine, disable
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| 95 | * interrupts. This is a very heavy lock, which is equivalent to
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| 96 | * grabbing every spinlock (and more). So the "read" side to such a
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| 97 | * lock is anything which disables preemption.
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| 98 |
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| 99 | #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
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| 100 |
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| 101 | |
| 102 | * stop_machine: freeze the machine on all CPUs and run this function
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| 103 | * @fn: the function to run
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| 104 | * @data: the data ptr for the @fn()
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| 105 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
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| 106 | *
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| 107 | * Description: This causes a thread to be scheduled on every cpu,
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| 108 | * each of which disables interrupts. The result is that no one is
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| 109 | * holding a spinlock or inside any other preempt-disabled region when
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| 110 | * @fn() runs.
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| 111 | *
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| 112 | * This can be thought of as a very heavy write lock, equivalent to
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| 113 | * grabbing every spinlock in the kernel.
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| 114 | int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
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| 115 |
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| 116 | |
| 117 | * __stop_machine: freeze the machine on all CPUs and run this function
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| 118 | * @fn: the function to run
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| 119 | * @data: the data ptr for the @fn
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| 120 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
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| 121 | *
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| 122 | * Description: This is a special version of the above, which assumes cpus
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| 123 | * won't come or go while it's being called. Used by hotplug cpu.
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| 124 |
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| 125 | int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
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| 126 |
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| 127 | int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
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| 128 | const struct cpumask *cpus);
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| 129 |
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| 130 | #else
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| 131 |
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| 132 | static inline int __stop_machine(int (*fn)(void *), void *data,
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| 133 | const struct cpumask *cpus)
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| 134 | {
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| 135 | unsigned long flags;
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| 136 | int ret;
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| 137 | local_irq_save(flags);
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| 138 | ret = fn(data);
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| 139 | local_irq_restore(flags);
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| 140 | return ret;
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| 141 | }
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| 142 |
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| 143 | static inline int stop_machine(int (*fn)(void *), void *data,
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| 144 | const struct cpumask *cpus)
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| 145 | {
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| 146 | return __stop_machine(fn, data, cpus);
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| 147 | }
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| 148 |
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| 149 | static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
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| 150 | const struct cpumask *cpus)
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| 151 | {
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| 152 | return __stop_machine(fn, data, cpus);
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| 153 | }
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| 154 |
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| 155 | #endif
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| 156 | #endif
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