1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_STOP_MACHINE 3 #define _LINUX_STOP_MACHINE 4 5 #include <linux/cpu.h> 6 #include <linux/cpumask_types.h> 7 #include <linux/smp.h> 8 #include <linux/list.h> 9 10 /* 11 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu 12 * monopolization mechanism. The caller can specify a non-sleeping 13 * function to be executed on a single or multiple cpus preempting all 14 * other processes and monopolizing those cpus until it finishes. 15 * 16 * Resources for this mechanism are preallocated when a cpu is brought 17 * up and requests are guaranteed to be served as long as the target 18 * cpus are online. 19 */ 20 typedef int (*cpu_stop_fn_t)(void *arg); 21 22 #ifdef CONFIG_SMP 23 24 struct cpu_stop_work { 25 struct list_head list; /* cpu_stopper->works */ 26 cpu_stop_fn_t fn; 27 unsigned long caller; 28 void *arg; 29 struct cpu_stop_done *done; 30 }; 31 32 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); 33 int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); 34 bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, 35 struct cpu_stop_work *work_buf); 36 void stop_machine_park(int cpu); 37 void stop_machine_unpark(int cpu); 38 void stop_machine_yield(const struct cpumask *cpumask); 39 40 extern void print_stop_info(const char *log_lvl, struct task_struct *task); 41 42 #else /* CONFIG_SMP */ 43 44 #include <linux/workqueue.h> 45 46 struct cpu_stop_work { 47 struct work_struct work; 48 cpu_stop_fn_t fn; 49 void *arg; 50 }; 51 stop_one_cpu(unsigned int cpu,cpu_stop_fn_t fn,void * arg)52 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) 53 { 54 int ret = -ENOENT; 55 preempt_disable(); 56 if (cpu == smp_processor_id()) 57 ret = fn(arg); 58 preempt_enable(); 59 return ret; 60 } 61 stop_one_cpu_nowait_workfn(struct work_struct * work)62 static void stop_one_cpu_nowait_workfn(struct work_struct *work) 63 { 64 struct cpu_stop_work *stwork = 65 container_of(work, struct cpu_stop_work, work); 66 preempt_disable(); 67 stwork->fn(stwork->arg); 68 preempt_enable(); 69 } 70 stop_one_cpu_nowait(unsigned int cpu,cpu_stop_fn_t fn,void * arg,struct cpu_stop_work * work_buf)71 static inline bool stop_one_cpu_nowait(unsigned int cpu, 72 cpu_stop_fn_t fn, void *arg, 73 struct cpu_stop_work *work_buf) 74 { 75 if (cpu == smp_processor_id()) { 76 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); 77 work_buf->fn = fn; 78 work_buf->arg = arg; 79 schedule_work(&work_buf->work); 80 return true; 81 } 82 83 return false; 84 } 85 print_stop_info(const char * log_lvl,struct task_struct * task)86 static inline void print_stop_info(const char *log_lvl, struct task_struct *task) { } 87 88 #endif /* CONFIG_SMP */ 89 90 /* 91 * stop_machine "Bogolock": stop the entire machine, disable 92 * interrupts. This is a very heavy lock, which is equivalent to 93 * grabbing every spinlock (and more). So the "read" side to such a 94 * lock is anything which disables preemption. 95 */ 96 #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) 97 98 /** 99 * stop_machine: freeze the machine on all CPUs and run this function 100 * @fn: the function to run 101 * @data: the data ptr for the @fn() 102 * @cpus: the cpus to run the @fn() on (NULL = any online cpu) 103 * 104 * Description: This causes a thread to be scheduled on every cpu, 105 * each of which disables interrupts. The result is that no one is 106 * holding a spinlock or inside any other preempt-disabled region when 107 * @fn() runs. 108 * 109 * This can be thought of as a very heavy write lock, equivalent to 110 * grabbing every spinlock in the kernel. 111 * 112 * Protects against CPU hotplug. 113 */ 114 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 115 116 /** 117 * stop_machine_cpuslocked: 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 * Same as above. Must be called from with in a cpus_read_lock() protected 123 * region. Avoids nested calls to cpus_read_lock(). 124 */ 125 int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 126 127 /** 128 * stop_core_cpuslocked: - stop all threads on just one core 129 * @cpu: any cpu in the targeted core 130 * @fn: the function to run 131 * @data: the data ptr for @fn() 132 * 133 * Same as above, but instead of every CPU, only the logical CPUs of a 134 * single core are affected. 135 * 136 * Context: Must be called from within a cpus_read_lock() protected region. 137 * 138 * Return: 0 if all executions of @fn returned 0, any non zero return 139 * value if any returned non zero. 140 */ 141 int stop_core_cpuslocked(unsigned int cpu, cpu_stop_fn_t fn, void *data); 142 143 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 144 const struct cpumask *cpus); 145 #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ 146 stop_machine_cpuslocked(cpu_stop_fn_t fn,void * data,const struct cpumask * cpus)147 static __always_inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, 148 const struct cpumask *cpus) 149 { 150 unsigned long flags; 151 int ret; 152 local_irq_save(flags); 153 ret = fn(data); 154 local_irq_restore(flags); 155 return ret; 156 } 157 158 static __always_inline int stop_machine(cpu_stop_fn_t fn,void * data,const struct cpumask * cpus)159 stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) 160 { 161 return stop_machine_cpuslocked(fn, data, cpus); 162 } 163 164 static __always_inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn,void * data,const struct cpumask * cpus)165 stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, 166 const struct cpumask *cpus) 167 { 168 return stop_machine(fn, data, cpus); 169 } 170 171 #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ 172 #endif /* _LINUX_STOP_MACHINE */ 173