cregit-Linux how code gets into the kernel

Release 4.7 include/linux/stop_machine.h

Directory: include/linux
#ifndef _LINUX_STOP_MACHINE

#define _LINUX_STOP_MACHINE

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
#include <linux/list.h>

/*
 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
 * monopolization mechanism.  The caller can specify a non-sleeping
 * function to be executed on a single or multiple cpus preempting all
 * other processes and monopolizing those cpus until it finishes.
 *
 * Resources for this mechanism are preallocated when a cpu is brought
 * up and requests are guaranteed to be served as long as the target
 * cpus are online.
 */

typedef int (*cpu_stop_fn_t)(void *arg);

#ifdef CONFIG_SMP


struct cpu_stop_work {
	
struct list_head	list;		/* cpu_stopper->works */
	
cpu_stop_fn_t		fn;
	
void			*arg;
	
struct cpu_stop_done	*done;
};

int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg);
bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
			 struct cpu_stop_work *work_buf);
int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
void stop_machine_park(int cpu);
void stop_machine_unpark(int cpu);

#else	/* CONFIG_SMP */

#include <linux/workqueue.h>


struct cpu_stop_work {
	
struct work_struct	work;
	
cpu_stop_fn_t		fn;
	
void			*arg;
};


static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) { int ret = -ENOENT; preempt_disable(); if (cpu == smp_processor_id()) ret = fn(arg); preempt_enable(); return ret; }

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static void stop_one_cpu_nowait_workfn(struct work_struct *work) { struct cpu_stop_work *stwork = container_of(work, struct cpu_stop_work, work); preempt_disable(); stwork->fn(stwork->arg); preempt_enable(); }

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static inline bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf) { if (cpu == smp_processor_id()) { INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); work_buf->fn = fn; work_buf->arg = arg; schedule_work(&work_buf->work); return true; } return false; }

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static inline int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) { if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) return stop_one_cpu(raw_smp_processor_id(), fn, arg); return -ENOENT; }

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static inline int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) { return stop_cpus(cpumask, fn, arg); }

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#endif /* CONFIG_SMP */ /* * stop_machine "Bogolock": stop the entire machine, disable * interrupts. This is a very heavy lock, which is equivalent to * grabbing every spinlock (and more). So the "read" side to such a * lock is anything which disables preemption. */ #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) /** * stop_machine: freeze the machine on all CPUs and run this function * @fn: the function to run * @data: the data ptr for the @fn() * @cpus: the cpus to run the @fn() on (NULL = any online cpu) * * Description: This causes a thread to be scheduled on every cpu, * each of which disables interrupts. The result is that no one is * holding a spinlock or inside any other preempt-disabled region when * @fn() runs. * * This can be thought of as a very heavy write lock, equivalent to * grabbing every spinlock in the kernel. */ int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
static inline int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) { unsigned long flags; int ret; local_irq_save(flags); ret = fn(data); local_irq_restore(flags); return ret; }

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static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) { return stop_machine(fn, data, cpus); }

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#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ #endif /* _LINUX_STOP_MACHINE */

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Directory: include/linux
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