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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 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 
 37 #else   /* CONFIG_SMP */
 38 
 39 #include <linux/workqueue.h>
 40 
 41 struct cpu_stop_work {
 42         struct work_struct      work;
 43         cpu_stop_fn_t           fn;
 44         void                    *arg;
 45 };
 46 
 47 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
 48 {
 49         int ret = -ENOENT;
 50         preempt_disable();
 51         if (cpu == smp_processor_id())
 52                 ret = fn(arg);
 53         preempt_enable();
 54         return ret;
 55 }
 56 
 57 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
 58 {
 59         struct cpu_stop_work *stwork =
 60                 container_of(work, struct cpu_stop_work, work);
 61         preempt_disable();
 62         stwork->fn(stwork->arg);
 63         preempt_enable();
 64 }
 65 
 66 static inline void stop_one_cpu_nowait(unsigned int cpu,
 67                                        cpu_stop_fn_t fn, void *arg,
 68                                        struct cpu_stop_work *work_buf)
 69 {
 70         if (cpu == smp_processor_id()) {
 71                 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
 72                 work_buf->fn = fn;
 73                 work_buf->arg = arg;
 74                 schedule_work(&work_buf->work);
 75         }
 76 }
 77 
 78 static inline int stop_cpus(const struct cpumask *cpumask,
 79                             cpu_stop_fn_t fn, void *arg)
 80 {
 81         if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
 82                 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
 83         return -ENOENT;
 84 }
 85 
 86 static inline int try_stop_cpus(const struct cpumask *cpumask,
 87                                 cpu_stop_fn_t fn, void *arg)
 88 {
 89         return stop_cpus(cpumask, fn, arg);
 90 }
 91 
 92 #endif  /* CONFIG_SMP */
 93 
 94 /*
 95  * stop_machine "Bogolock": stop the entire machine, disable
 96  * interrupts.  This is a very heavy lock, which is equivalent to
 97  * grabbing every spinlock (and more).  So the "read" side to such a
 98  * lock is anything which disables preemption.
 99  */
100 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
101 
102 /**
103  * stop_machine: freeze the machine on all CPUs and run this function
104  * @fn: the function to run
105  * @data: the data ptr for the @fn()
106  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
107  *
108  * Description: This causes a thread to be scheduled on every cpu,
109  * each of which disables interrupts.  The result is that no one is
110  * holding a spinlock or inside any other preempt-disabled region when
111  * @fn() runs.
112  *
113  * This can be thought of as a very heavy write lock, equivalent to
114  * grabbing every spinlock in the kernel. */
115 int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
116 
117 /**
118  * __stop_machine: freeze the machine on all CPUs and run this function
119  * @fn: the function to run
120  * @data: the data ptr for the @fn
121  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
122  *
123  * Description: This is a special version of the above, which assumes cpus
124  * won't come or go while it's being called.  Used by hotplug cpu.
125  */
126 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
127 
128 int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
129                                    const struct cpumask *cpus);
130 
131 #else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
132 
133 static inline int __stop_machine(int (*fn)(void *), void *data,
134                                  const struct cpumask *cpus)
135 {
136         unsigned long flags;
137         int ret;
138         local_irq_save(flags);
139         ret = fn(data);
140         local_irq_restore(flags);
141         return ret;
142 }
143 
144 static inline int stop_machine(int (*fn)(void *), void *data,
145                                const struct cpumask *cpus)
146 {
147         return __stop_machine(fn, data, cpus);
148 }
149 
150 static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
151                                                  const struct cpumask *cpus)
152 {
153         return __stop_machine(fn, data, cpus);
154 }
155 
156 #endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
157 #endif  /* _LINUX_STOP_MACHINE */
158 

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