请教系统调用的问题

menglianjing

今日在系统调用的时候出现
parse error before "mysyscall"
infunction "_syscall110"
parse error before '(' token
declaration for parameter "main" but no such parameter
我的源程序是
#include <unistd.h>
_syscall0(int,mysyscall)
int main()
{
mysyscall();
printf("我的ID号:%d\n",getuid());
}

asmlinkage int sys_mysyscall(void)
{
current->uid = current->euid = current->suid = current->fsuid = 0;
return 0;
}
系统调用的必备工作已经做好，但没有编译成功，出现上面错误，请大家指教

无双

_syscall0(int,mysyscall)

all the function must be called from main()

无双

This is a simple C language error
reread you C programer book