Linux内核--从上向下分析驱动程序层

作者：网络转载发布时间：[ 2013/1/7 10:35:40 ] 推荐标签：

　其中的dev_tint()函数是将设备的所有缓存队列中的数据全部调用dev_queue_xmit()发送全部数据包。

/*
* This routine is called when an device driver (i.e. an
* interface) is ready to transmit a packet.
*/
//该函数功能:遍历设备的缓冲队列，对所有的数据包调用dev_queue_xmit()函数发送数据
void dev_tint(struct device *dev)
{
int i;
struct sk_buff *skb;
unsigned long flags;

save_flags(flags);
/*
* Work the queues in priority order
*/

for(i = 0;i < DEV_NUMBUFFS; i++)
{
/*
   * Pull packets from the queue
   */

cli();
while((skb=skb_dequeue(&dev->buffs[i]))!=NULL)
{
   /*
    * Stop anyone freeing the buffer while we retransmit it
    */
   skb_device_lock(skb);
   restore_flags(flags);
   /*
    * Feed them to the output stage and if it fails
    * indicate they re-queue at the front.
    */
   dev_queue_xmit(skb，dev，-i - 1);//注意优先级的计算方式，在函数dev_queue_xmit()中优先级若<0则计算pri=-pri-1=-(-i-1)-1=i，
             //这样做的目的是为了得到正确的where值，函数(dev_queue_xmit())中
   /*
    * If we can take no more then stop here.
    */
   if (dev->tbusy)
    return;
   cli();
}
}
restore_flags(flags);
}