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TOMOYO Linux Cross Reference
Linux/include/linux/stop_machine.h

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  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.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         void                    *arg;
 28         struct cpu_stop_done    *done;
 29 };
 30 
 31 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
 32 int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg);
 33 bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
 34                          struct cpu_stop_work *work_buf);
 35 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
 36 int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
 37 void stop_machine_park(int cpu);
 38 void stop_machine_unpark(int cpu);
 39 
 40 #else   /* CONFIG_SMP */
 41 
 42 #include <linux/workqueue.h>
 43 
 44 struct cpu_stop_work {
 45         struct work_struct      work;
 46         cpu_stop_fn_t           fn;
 47         void                    *arg;
 48 };
 49 
 50 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
 51 {
 52         int ret = -ENOENT;
 53         preempt_disable();
 54         if (cpu == smp_processor_id())
 55                 ret = fn(arg);
 56         preempt_enable();
 57         return ret;
 58 }
 59 
 60 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
 61 {
 62         struct cpu_stop_work *stwork =
 63                 container_of(work, struct cpu_stop_work, work);
 64         preempt_disable();
 65         stwork->fn(stwork->arg);
 66         preempt_enable();
 67 }
 68 
 69 static inline bool stop_one_cpu_nowait(unsigned int cpu,
 70                                        cpu_stop_fn_t fn, void *arg,
 71                                        struct cpu_stop_work *work_buf)
 72 {
 73         if (cpu == smp_processor_id()) {
 74                 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
 75                 work_buf->fn = fn;
 76                 work_buf->arg = arg;
 77                 schedule_work(&work_buf->work);
 78                 return true;
 79         }
 80 
 81         return false;
 82 }
 83 
 84 static inline int stop_cpus(const struct cpumask *cpumask,
 85                             cpu_stop_fn_t fn, void *arg)
 86 {
 87         if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
 88                 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
 89         return -ENOENT;
 90 }
 91 
 92 static inline int try_stop_cpus(const struct cpumask *cpumask,
 93                                 cpu_stop_fn_t fn, void *arg)
 94 {
 95         return stop_cpus(cpumask, fn, arg);
 96 }
 97 
 98 #endif  /* CONFIG_SMP */
 99 
100 /*
101  * stop_machine "Bogolock": stop the entire machine, disable
102  * interrupts.  This is a very heavy lock, which is equivalent to
103  * grabbing every spinlock (and more).  So the "read" side to such a
104  * lock is anything which disables preemption.
105  */
106 #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
107 
108 /**
109  * stop_machine: freeze the machine on all CPUs and run this function
110  * @fn: the function to run
111  * @data: the data ptr for the @fn()
112  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
113  *
114  * Description: This causes a thread to be scheduled on every cpu,
115  * each of which disables interrupts.  The result is that no one is
116  * holding a spinlock or inside any other preempt-disabled region when
117  * @fn() runs.
118  *
119  * This can be thought of as a very heavy write lock, equivalent to
120  * grabbing every spinlock in the kernel.
121  *
122  * Protects against CPU hotplug.
123  */
124 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
125 
126 /**
127  * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function
128  * @fn: the function to run
129  * @data: the data ptr for the @fn()
130  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
131  *
132  * Same as above. Must be called from with in a cpus_read_lock() protected
133  * region. Avoids nested calls to cpus_read_lock().
134  */
135 int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
136 
137 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
138                                    const struct cpumask *cpus);
139 #else   /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
140 
141 static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,
142                                           const struct cpumask *cpus)
143 {
144         unsigned long flags;
145         int ret;
146         local_irq_save(flags);
147         ret = fn(data);
148         local_irq_restore(flags);
149         return ret;
150 }
151 
152 static inline int stop_machine(cpu_stop_fn_t fn, void *data,
153                                const struct cpumask *cpus)
154 {
155         return stop_machine_cpuslocked(fn, data, cpus);
156 }
157 
158 static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
159                                                  const struct cpumask *cpus)
160 {
161         return stop_machine(fn, data, cpus);
162 }
163 
164 #endif  /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
165 #endif  /* _LINUX_STOP_MACHINE */
166 

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