1#ifndef _LINUX_STOP_MACHINE 2#define _LINUX_STOP_MACHINE 3 4#include <linux/cpu.h> 5#include <linux/cpumask.h> 6#include <linux/smp.h> 7#include <linux/list.h> 8 9/* 10 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu 11 * monopolization mechanism. The caller can specify a non-sleeping 12 * function to be executed on a single or multiple cpus preempting all 13 * other processes and monopolizing those cpus until it finishes. 14 * 15 * Resources for this mechanism are preallocated when a cpu is brought 16 * up and requests are guaranteed to be served as long as the target 17 * cpus are online. 18 */ 19typedef int (*cpu_stop_fn_t)(void *arg); 20 21#ifdef CONFIG_SMP 22 23struct cpu_stop_work { 24 struct list_head list; /* cpu_stopper->works */ 25 cpu_stop_fn_t fn; 26 void *arg; 27 struct cpu_stop_done *done; 28}; 29 30int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); 31int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); 32void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, 33 struct cpu_stop_work *work_buf); 34int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 35int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 36void stop_machine_park(int cpu); 37void stop_machine_unpark(int cpu); 38 39#else /* CONFIG_SMP */ 40 41#include <linux/workqueue.h> 42 43struct cpu_stop_work { 44 struct work_struct work; 45 cpu_stop_fn_t fn; 46 void *arg; 47}; 48 49static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) 50{ 51 int ret = -ENOENT; 52 preempt_disable(); 53 if (cpu == smp_processor_id()) 54 ret = fn(arg); 55 preempt_enable(); 56 return ret; 57} 58 59static void stop_one_cpu_nowait_workfn(struct work_struct *work) 60{ 61 struct cpu_stop_work *stwork = 62 container_of(work, struct cpu_stop_work, work); 63 preempt_disable(); 64 stwork->fn(stwork->arg); 65 preempt_enable(); 66} 67 68static inline void stop_one_cpu_nowait(unsigned int cpu, 69 cpu_stop_fn_t fn, void *arg, 70 struct cpu_stop_work *work_buf) 71{ 72 if (cpu == smp_processor_id()) { 73 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); 74 work_buf->fn = fn; 75 work_buf->arg = arg; 76 schedule_work(&work_buf->work); 77 } 78} 79 80static inline int stop_cpus(const struct cpumask *cpumask, 81 cpu_stop_fn_t fn, void *arg) 82{ 83 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) 84 return stop_one_cpu(raw_smp_processor_id(), fn, arg); 85 return -ENOENT; 86} 87 88static inline int try_stop_cpus(const struct cpumask *cpumask, 89 cpu_stop_fn_t fn, void *arg) 90{ 91 return stop_cpus(cpumask, fn, arg); 92} 93 94#endif /* CONFIG_SMP */ 95 96/* 97 * stop_machine "Bogolock": stop the entire machine, disable 98 * interrupts. This is a very heavy lock, which is equivalent to 99 * grabbing every spinlock (and more). So the "read" side to such a 100 * lock is anything which disables preemption. 101 */ 102#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) 103 104/** 105 * stop_machine: freeze the machine on all CPUs and run this function 106 * @fn: the function to run 107 * @data: the data ptr for the @fn() 108 * @cpus: the cpus to run the @fn() on (NULL = any online cpu) 109 * 110 * Description: This causes a thread to be scheduled on every cpu, 111 * each of which disables interrupts. The result is that no one is 112 * holding a spinlock or inside any other preempt-disabled region when 113 * @fn() runs. 114 * 115 * This can be thought of as a very heavy write lock, equivalent to 116 * grabbing every spinlock in the kernel. */ 117int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 118 119int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 120 const struct cpumask *cpus); 121#else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ 122 123static inline int stop_machine(cpu_stop_fn_t fn, void *data, 124 const struct cpumask *cpus) 125{ 126 unsigned long flags; 127 int ret; 128 local_irq_save(flags); 129 ret = fn(data); 130 local_irq_restore(flags); 131 return ret; 132} 133 134static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 135 const struct cpumask *cpus) 136{ 137 return stop_machine(fn, data, cpus); 138} 139 140#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ 141#endif /* _LINUX_STOP_MACHINE */ 142