smp_call_function 功能

2024-06-03 16:32

文章标签 功能 call function smp

本文主要是介绍smp_call_function 功能，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

转自：

http://blog.csdn.net/zhangxx0811/article/details/8479969

crash_kexec -> machine_crash_shutdown -> smp_call_function(machine_crash_nonpanic_core, NULL, false);

当一个CPU crash 后，通知其他CPU stop doing anything useful.

void machine_crash_nonpanic_core(void *unused)
{
   struct pt_regs regs;

   crash_setup_regs(&regs, NULL);
   printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",
           smp_processor_id());
   crash_save_cpu(&regs, smp_processor_id());
   flush_cache_all();

   atomic_dec(&waiting_for_crash_ipi);
   while (1)
       cpu_relax();
}

int smp_call_function(smp_call_func_t func, void *info, int wait);

在 smp机器上,除了正在调用smp_call_function之外的所有核调用 func .

例子.

#include <linux/kernel.h>
#include <linux/module.h>
#if CONFIG_MODVERSIONS==1
#define MODVERSIONS
#include<linux/modversions.h>
#endif

#include <asm/uaccess.h>
#include <linux/ctype.h>
#include <linux/smp.h>

int print_id(int cpuid)
{
int cpu=smp_processor_id();
// if(cpuid==smp_processor_id())
{
printk("myid %d\n",cpu);
}
return 0;
}

MODULE_LICENSE("GPL");
int init_module()
{
//printk("hello.word-this is the kernel speaking\n");
int cpu=0;
if(cpu==smp_processor_id())
{
printk("myid is %d\n",0);
}
else
{
smp_call_function(print_id,&cpu,1);
}

return 0;
}

void cleanup_module()
{
int cpu=0;
printk("Short is the life of a kernel module\n");
if(cpu==smp_processor_id())
{
printk("myid is %d\n",0);
}