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 bool 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 bool 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 return true; 78 } 79 80 return false; 81 } 82 83 static inline int stop_cpus(const struct cpumask *cpumask, 84 cpu_stop_fn_t fn, void *arg) 85 { 86 if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) 87 return stop_one_cpu(raw_smp_processor_id(), fn, arg); 88 return -ENOENT; 89 } 90 91 static inline int try_stop_cpus(const struct cpumask *cpumask, 92 cpu_stop_fn_t fn, void *arg) 93 { 94 return stop_cpus(cpumask, fn, arg); 95 } 96 97 #endif /* CONFIG_SMP */ 98 99 /* 100 * stop_machine "Bogolock": stop the entire machine, disable 101 * interrupts. This is a very heavy lock, which is equivalent to 102 * grabbing every spinlock (and more). So the "read" side to such a 103 * lock is anything which disables preemption. 104 */ 105 #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) 106 107 /** 108 * stop_machine: freeze the machine on all CPUs and run this function 109 * @fn: the function to run 110 * @data: the data ptr for the @fn() 111 * @cpus: the cpus to run the @fn() on (NULL = any online cpu) 112 * 113 * Description: This causes a thread to be scheduled on every cpu, 114 * each of which disables interrupts. The result is that no one is 115 * holding a spinlock or inside any other preempt-disabled region when 116 * @fn() runs. 117 * 118 * This can be thought of as a very heavy write lock, equivalent to 119 * grabbing every spinlock in the kernel. 120 * 121 * Protects against CPU hotplug. 122 */ 123 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 124 125 /** 126 * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function 127 * @fn: the function to run 128 * @data: the data ptr for the @fn() 129 * @cpus: the cpus to run the @fn() on (NULL = any online cpu) 130 * 131 * Same as above. Must be called from with in a cpus_read_lock() protected 132 * region. Avoids nested calls to cpus_read_lock(). 133 */ 134 int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 135 136 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 137 const struct cpumask *cpus); 138 #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ 139 140 static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, 141 const struct cpumask *cpus) 142 { 143 unsigned long flags; 144 int ret; 145 local_irq_save(flags); 146 ret = fn(data); 147 local_irq_restore(flags); 148 return ret; 149 } 150 151 static inline int stop_machine(cpu_stop_fn_t fn, void *data, 152 const struct cpumask *cpus) 153 { 154 return stop_machine_cpuslocked(fn, data, cpus); 155 } 156 157 static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 158 const struct cpumask *cpus) 159 { 160 return stop_machine(fn, data, cpus); 161 } 162 163 #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ 164 #endif /* _LINUX_STOP_MACHINE */ 165