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 */ 19 typedef int (*cpu_stop_fn_t)(void *arg); 20 21 #ifdef CONFIG_SMP 22 23 struct 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 30 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); 31 void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, 32 struct cpu_stop_work *work_buf); 33 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 34 int 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 40 struct cpu_stop_work { 41 struct work_struct work; 42 cpu_stop_fn_t fn; 43 void *arg; 44 }; 45 46 static 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 56 static 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 65 static 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 77 static 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 85 static 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 preemption. 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 no one 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. */ 114 int 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 */ 125 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); 126 127 int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, 128 const struct cpumask *cpus); 129 130 #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 131 132 static inline int __stop_machine(int (*fn)(void *), void *data, 133 const struct cpumask *cpus) 134 { 135 unsigned long flags; 136 int ret; 137 local_irq_save(flags); 138 ret = fn(data); 139 local_irq_restore(flags); 140 return ret; 141 } 142 143 static inline int stop_machine(int (*fn)(void *), void *data, 144 const struct cpumask *cpus) 145 { 146 return __stop_machine(fn, data, cpus); 147 } 148 149 static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, 150 const struct cpumask *cpus) 151 { 152 return __stop_machine(fn, data, cpus); 153 } 154 155 #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 156 #endif /* _LINUX_STOP_MACHINE */ 157