Passthru例子MPReturnPacket() 没有NdisFreeBuffer()，为什么？

帮助文档NdisFreePacket()函数中明确写着
Before calling NdisFreePacket, the driver either must call NdisFreeBuffer as many times as necessary to...
（在调用NdisFreePacket之前，驱动程序要么调用与XXX相等次数的NdisFreeBuffer，要么...）
但在MPReturnPacket例程中，却直接调用NdisFreePacket，没有 先调用NdisFreeBuffer，其源码如下：

PADAPT                  pAdapt = (PADAPT)MiniportAdapterContext;
PNDIS_PACKET   MyPacket;
PRSVD                Resvd;

Resvd = (PRSVD)(Packet->MiniportReserved);
MyPacket = Resvd->OriginalPkt;

NdisFreePacket(Packet);   // 就是这里不用先调用NdisFreeBuffer吗？
NdisReturnPackets(&MyPacket, 1);

谢谢了！