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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 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 int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
121 
122 int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
123                                    const struct cpumask *cpus);
124 #else   /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
125 
126 static inline int stop_machine(cpu_stop_fn_t fn, void *data,
127                                  const struct cpumask *cpus)
128 {
129         unsigned long flags;
130         int ret;
131         local_irq_save(flags);
132         ret = fn(data);
133         local_irq_restore(flags);
134         return ret;
135 }
136 
137 static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
138                                                  const struct cpumask *cpus)
139 {
140         return stop_machine(fn, data, cpus);
141 }
142 
143 #endif  /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
144 #endif  /* _LINUX_STOP_MACHINE */
145 

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