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 int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); 32 void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, 33 struct cpu_stop_work *work_buf); 34 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 35 int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); 36 void stop_machine_park(int cpu); 37 void stop_machine_unpark(int cpu); 38 39 #else /* CONFIG_SMP */ 40 41 #include <linux/workqueue.h> 42 43 struct cpu_stop_work { 44 struct work_struct work; 45 cpu_stop_fn_t fn; 46 void *arg; 47 }; 48 49 static 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 59 static 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 68 static 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 80 static 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 88 static 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_STOP_MACHINE) && defined(CONFIG_SMP) 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. */ 117 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 118 119 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 120 const struct cpumask *cpus); 121 #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 122 123 static 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 } 133 134 static 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_STOP_MACHINE && CONFIG_SMP */ 141 #endif /* _LINUX_STOP_MACHINE */ 142