include/linux/stop_machine.h

Source file repositories/reference/linux-study-clean/include/linux/stop_machine.h

File Facts

System
Linux kernel
Corpus path
include/linux/stop_machine.h
Extension
.h
Size
6198 bytes
Lines
191
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct cpu_stop_work {
	struct list_head	list;		/* cpu_stopper->works */
	cpu_stop_fn_t		fn;
	unsigned long		caller;
	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);
void stop_machine_park(int cpu);
void stop_machine_unpark(int cpu);
void stop_machine_yield(const struct cpumask *cpumask);

extern void print_stop_info(const char *log_lvl, struct task_struct *task);

#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;
}

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();
}

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;
}

static inline void print_stop_info(const char *log_lvl, struct task_struct *task) { }

#endif	/* CONFIG_SMP */

/*
 * stop_machine "Bogolock": stop the entire machine, disable interrupts.
 * This is a very heavy lock, which is equivalent to grabbing every raw
 * 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 to pass to @fn()
 * @cpus: the cpus to run @fn() on (NULL = one unspecified online CPU)
 *
 * Description: This causes a thread to be scheduled on every CPU, which
 * will run with interrupts disabled.  Each CPU specified by @cpus will
 * run @fn.  While @fn is executing, there will no other CPUs holding
 * a raw spinlock or running within any other type of preempt-disabled
 * region of code.
 *
 * When @cpus specifies only a single CPU, this can be thought of as
 * a reader-writer lock where readers disable preemption (for example,
 * by holding a raw spinlock) and where the insanely heavy writers run
 * @fn while also preventing any other CPU from doing any useful work.

Annotation

Implementation Notes