1#ifndef _LINUX_STOP_MACHINE 2#define _LINUX_STOP_MACHINE 3 4#include <linux/cpu.h> 5#include <linux/cpumask.h> 6#include <linux/list.h> 7#include <asm/system.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); 31void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, 32 struct cpu_stop_work *work_buf); 33int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 34int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 35 36#else /* CONFIG_SMP */ 37 38#include <linux/workqueue.h> 39 40struct cpu_stop_work { 41 struct work_struct work; 42 cpu_stop_fn_t fn; 43 void *arg; 44}; 45 46static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) 47{ 48 int ret = -ENOENT; 49 preempt_disable(); 50 if (cpu == smp_processor_id()) 51 ret = fn(arg); 52 preempt_enable(); 53 return ret; 54} 55 56static void stop_one_cpu_nowait_workfn(struct work_struct *work) 57{ 58 struct cpu_stop_work *stwork = 59 container_of(work, struct cpu_stop_work, work); 60 preempt_disable(); 61 stwork->fn(stwork->arg); 62 preempt_enable(); 63} 64 65static inline void stop_one_cpu_nowait(unsigned int cpu, 66 cpu_stop_fn_t fn, void *arg, 67 struct cpu_stop_work *work_buf) 68{ 69 if (cpu == smp_processor_id()) { 70 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); 71 work_buf->fn = fn; 72 work_buf->arg = arg; 73 schedule_work(&work_buf->work); 74 } 75} 76 77static inline int stop_cpus(const struct cpumask *cpumask, 78 cpu_stop_fn_t fn, void *arg) 79{ 80 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) 81 return stop_one_cpu(raw_smp_processor_id(), fn, arg); 82 return -ENOENT; 83} 84 85static inline int try_stop_cpus(const struct cpumask *cpumask, 86 cpu_stop_fn_t fn, void *arg) 87{ 88 return stop_cpus(cpumask, fn, arg); 89} 90 91#endif /* CONFIG_SMP */ 92 93/* 94 * stop_machine "Bogolock": stop the entire machine, disable 95 * interrupts. This is a very heavy lock, which is equivalent to 96 * grabbing every spinlock (and more). So the "read" side to such a 97 * lock is anything which disables preeempt. 98 */ 99#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP) 100 101/** 102 * stop_machine: freeze the machine on all CPUs and run this function 103 * @fn: the function to run 104 * @data: the data ptr for the @fn() 105 * @cpus: the cpus to run the @fn() on (NULL = any online cpu) 106 * 107 * Description: This causes a thread to be scheduled on every cpu, 108 * each of which disables interrupts. The result is that noone is 109 * holding a spinlock or inside any other preempt-disabled region when 110 * @fn() runs. 111 * 112 * This can be thought of as a very heavy write lock, equivalent to 113 * grabbing every spinlock in the kernel. */ 114int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); 115 116/** 117 * __stop_machine: 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 * Description: This is a special version of the above, which assumes cpus 123 * won't come or go while it's being called. Used by hotplug cpu. 124 */ 125int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); 126 127#else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 128 129static inline int stop_machine(int (*fn)(void *), void *data, 130 const struct cpumask *cpus) 131{ 132 int ret; 133 local_irq_disable(); 134 ret = fn(data); 135 local_irq_enable(); 136 return ret; 137} 138 139#endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 140#endif /* _LINUX_STOP_MACHINE */ 141