dp_packet_reset_packet(struct dp_packet *b, int off)
{
    dp_packet_set_size(b, dp_packet_size(b) - off);
    dp_packet_set_data(b, ((unsigned char *) dp_packet_data(b) + off));
    dp_packet_reset_offsets(b);
}
dp_packet_reset_packet(struct dp_packet *b, int off)
{
    dp_packet_set_size(b, dp_packet_size(b) - off);
    dp_packet_set_data(b, ((unsigned char *) dp_packet_data(b) + off));
    dp_packet_reset_offsets(b);
}