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

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  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 void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
 32                          struct cpu_stop_work *work_buf);
 33 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
 34 int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
 35 
 36 #else   /* CONFIG_SMP */
 37 
 38 #include <linux/workqueue.h>
 39 
 40 struct cpu_stop_work {
 41         struct work_struct      work;
 42         cpu_stop_fn_t           fn;
 43         void                    *arg;
 44 };
 45 
 46 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
 47 {
 48         int ret = -ENOENT;
 49         preempt_disable();
 50         if (cpu == smp_processor_id())
 51                 ret = fn(arg);
 52         preempt_enable();
 53         return ret;
 54 }
 55 
 56 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
 57 {
 58         struct cpu_stop_work *stwork =
 59                 container_of(work, struct cpu_stop_work, work);
 60         preempt_disable();
 61         stwork->fn(stwork->arg);
 62         preempt_enable();
 63 }
 64 
 65 static inline void stop_one_cpu_nowait(unsigned int cpu,
 66                                        cpu_stop_fn_t fn, void *arg,
 67                                        struct cpu_stop_work *work_buf)
 68 {
 69         if (cpu == smp_processor_id()) {
 70                 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
 71                 work_buf->fn = fn;
 72                 work_buf->arg = arg;
 73                 schedule_work(&work_buf->work);
 74         }
 75 }
 76 
 77 static inline int stop_cpus(const struct cpumask *cpumask,
 78                             cpu_stop_fn_t fn, void *arg)
 79 {
 80         if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
 81                 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
 82         return -ENOENT;
 83 }
 84 
 85 static inline int try_stop_cpus(const struct cpumask *cpumask,
 86                                 cpu_stop_fn_t fn, void *arg)
 87 {
 88         return stop_cpus(cpumask, fn, arg);
 89 }
 90 
 91 #endif  /* CONFIG_SMP */
 92 
 93 /*
 94  * stop_machine "Bogolock": stop the entire machine, disable
 95  * interrupts.  This is a very heavy lock, which is equivalent to
 96  * grabbing every spinlock (and more).  So the "read" side to such a
 97  * lock is anything which disables preemption.
 98  */
 99 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
100 
101 /**
102  * stop_machine: freeze the machine on all CPUs and run this function
103  * @fn: the function to run
104  * @data: the data ptr for the @fn()
105  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
106  *
107  * Description: This causes a thread to be scheduled on every cpu,
108  * each of which disables interrupts.  The result is that no one is
109  * holding a spinlock or inside any other preempt-disabled region when
110  * @fn() runs.
111  *
112  * This can be thought of as a very heavy write lock, equivalent to
113  * grabbing every spinlock in the kernel. */
114 int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
115 
116 /**
117  * __stop_machine: 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  * Description: This is a special version of the above, which assumes cpus
123  * won't come or go while it's being called.  Used by hotplug cpu.
124  */
125 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
126 
127 int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
128                                    const struct cpumask *cpus);
129 
130 #else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
131 
132 static inline int __stop_machine(int (*fn)(void *), void *data,
133                                  const struct cpumask *cpus)
134 {
135         unsigned long flags;
136         int ret;
137         local_irq_save(flags);
138         ret = fn(data);
139         local_irq_restore(flags);
140         return ret;
141 }
142 
143 static inline int stop_machine(int (*fn)(void *), void *data,
144                                const struct cpumask *cpus)
145 {
146         return __stop_machine(fn, data, cpus);
147 }
148 
149 static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
150                                                  const struct cpumask *cpus)
151 {
152         return __stop_machine(fn, data, cpus);
153 }
154 
155 #endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
156 #endif  /* _LINUX_STOP_MACHINE */
157 

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