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 38 #else /* CONFIG_SMP */ 39 40 #include <linux/workqueue.h> 41 42 struct cpu_stop_work { 43 struct work_struct work; 44 cpu_stop_fn_t fn; 45 void *arg; 46 }; 47 48 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) 49 { 50 int ret = -ENOENT; 51 preempt_disable(); 52 if (cpu == smp_processor_id()) 53 ret = fn(arg); 54 preempt_enable(); 55 return ret; 56 } 57 58 static void stop_one_cpu_nowait_workfn(struct work_struct *work) 59 { 60 struct cpu_stop_work *stwork = 61 container_of(work, struct cpu_stop_work, work); 62 preempt_disable(); 63 stwork->fn(stwork->arg); 64 preempt_enable(); 65 } 66 67 static inline void stop_one_cpu_nowait(unsigned int cpu, 68 cpu_stop_fn_t fn, void *arg, 69 struct cpu_stop_work *work_buf) 70 { 71 if (cpu == smp_processor_id()) { 72 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); 73 work_buf->fn = fn; 74 work_buf->arg = arg; 75 schedule_work(&work_buf->work); 76 } 77 } 78 79 static inline int stop_cpus(const struct cpumask *cpumask, 80 cpu_stop_fn_t fn, void *arg) 81 { 82 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) 83 return stop_one_cpu(raw_smp_processor_id(), fn, arg); 84 return -ENOENT; 85 } 86 87 static inline int try_stop_cpus(const struct cpumask *cpumask, 88 cpu_stop_fn_t fn, void *arg) 89 { 90 return stop_cpus(cpumask, fn, arg); 91 } 92 93 #endif /* CONFIG_SMP */ 94 95 /* 96 * stop_machine "Bogolock": stop the entire machine, disable 97 * interrupts. This is a very heavy lock, which is equivalent to 98 * grabbing every spinlock (and more). So the "read" side to such a 99 * lock is anything which disables preemption. 100 */ 101 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP) 102 103 /** 104 * stop_machine: freeze the machine on all CPUs and run this function 105 * @fn: the function to run 106 * @data: the data ptr for the @fn() 107 * @cpus: the cpus to run the @fn() on (NULL = any online cpu) 108 * 109 * Description: This causes a thread to be scheduled on every cpu, 110 * each of which disables interrupts. The result is that no one is 111 * holding a spinlock or inside any other preempt-disabled region when 112 * @fn() runs. 113 * 114 * This can be thought of as a very heavy write lock, equivalent to 115 * grabbing every spinlock in the kernel. */ 116 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 117 118 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 119 const struct cpumask *cpus); 120 #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 121 122 static inline int stop_machine(cpu_stop_fn_t fn, void *data, 123 const struct cpumask *cpus) 124 { 125 unsigned long flags; 126 int ret; 127 local_irq_save(flags); 128 ret = fn(data); 129 local_irq_restore(flags); 130 return ret; 131 } 132 133 static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 134 const struct cpumask *cpus) 135 { 136 return stop_machine(fn, data, cpus); 137 } 138 139 #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */ 140 #endif /* _LINUX_STOP_MACHINE */ 141