ipq_mangle_ipv4 inside ipq_set_verdict

["Ju, Yu" <Yu.Ju@xxxxxxxxxxx>]

Hi,

Could some one tells me what does the following condition checking mean and
why it is there in the ipq_set_verdict? The code is form ip_queue.c of
kernel 2.6.11.

if (vmsg->data_len && vmsg->data_len == len)    /* what does this checking
mean and why it is needed? */
     if (ipq_mangle_ipv4(vmsg, entry) <  0)
            verdict = NF_DROP;

Thanks,
Yu