dpdk 自旋锁

#ifndef __SPIN_LOCK__
#define __SPIN_LOCK__

typedef struct {
    volatile int locked; /**< lock status 0 = unlocked, 1 = locked */
} rte_spinlock_t;

void rte_pause(){
        ;
}

//spinlock的初始化，lock=0，标识无锁状态
static inline void
rte_spinlock_init(rte_spinlock_t *sl)
{
    sl->locked = 0;
}

//加锁，也就是locked置1
static inline void
rte_spinlock_lock(rte_spinlock_t *sl)
{
    while (__sync_lock_test_and_set(&sl->locked, 1))
        while(sl->locked)
            rte_pause();
}

//解锁
static inline void
rte_spinlock_unlock (rte_spinlock_t *sl)
{
    __sync_lock_release(&sl->locked);
}

// 尝试加锁，如果当前状态是无锁，func返回1，标识加锁成功，失败func返回0
static inline int
rte_spinlock_trylock (rte_spinlock_t *sl)
{
    return (__sync_lock_test_and_set(&sl->locked,1) == 0);
}

//返回当前锁的status
static inline int rte_spinlock_is_locked (rte_spinlock_t *sl)
{
    return sl->locked;
}

#endif

#include "spinlock.h"
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

static int num =0; 
rte_spinlock_t retlock;

void *testfunc(void *arg)
{
    int i=0,t;
    for(i=0;i<20000;i++)
    {   
        rte_spinlock_lock(&retlock);
        num++;
        rte_spinlock_unlock(&retlock);
    }
}

int main()
{
        rte_spinlock_init(&retlock);

    pthread_t thread[20];
    int i;
    for(i=0;i<20;i++)
    {
        pthread_create(&thread[i],NULL,testfunc,NULL);
    }
    for(i=0;i<20;i++)
    {
        pthread_join(thread[i],NULL);
    }
    printf("%d
",num);
 }

root@ubuntu:~/dpdk-function# g++ -pthread  -o spinlock   spinlock_test.c
root@ubuntu:~/dpdk-function# ./spinlock 
400000
root@ubuntu:~/dpdk-function# 

/* file1.c */
#include <stdio.h>

static void fun(void)
{
    printf("hello from fun.
");
}

int main(void)
{
    fun();
    fun1();

    return 0;
}

/* file2.c */
#include <stdio.h>

static void fun1(void)
{
    printf("hello from static fun1.
");
}

/tmp/cc2VMzGR.o：在函数‘main’中：
static_fun.c:(.text+0x20)：对‘fun1’未定义的引用
collect2: error: ld returned 1 exit status