kernel_optimize_test/include/linux/stop_machine.h
Rusty Russell eeec4fad96 stop_machine(): stop_machine_run() changed to use cpu mask
Instead of a "cpu" arg with magic values NR_CPUS (any cpu) and ~0 (all
cpus), pass a cpumask_t.  Allow NULL for the common case (where we
don't care which CPU the function is run on): temporary cpumask_t's
are usually considered bad for stack space.

This deprecates stop_machine_run, to be removed soon when all the
callers are dead.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-28 12:16:30 +10:00

68 lines
2.1 KiB
C

#ifndef _LINUX_STOP_MACHINE
#define _LINUX_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
diables preeempt. */
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <asm/system.h>
#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
/* Deprecated, but useful for transition. */
#define ALL_CPUS ~0U
/**
* 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 noone 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(int (*fn)(void *), void *data, const cpumask_t *cpus);
/**
* __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 is a special version of the above, which assumes cpus
* won't come or go while it's being called. Used by hotplug cpu.
*/
int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
#else
static inline int stop_machine(int (*fn)(void *), void *data,
const cpumask_t *cpus)
{
int ret;
local_irq_disable();
ret = fn(data);
local_irq_enable();
return ret;
}
#endif /* CONFIG_SMP */
static inline int __deprecated stop_machine_run(int (*fn)(void *), void *data,
unsigned int cpu)
{
/* If they don't care which cpu fn runs on, just pick one. */
if (cpu == NR_CPUS)
return stop_machine(fn, data, NULL);
else if (cpu == ~0U)
return stop_machine(fn, data, &cpu_possible_map);
else {
cpumask_t cpus = cpumask_of_cpu(cpu);
return stop_machine(fn, data, &cpus);
}
}
#endif /* _LINUX_STOP_MACHINE */