Re: [Question]Why a skb with frag_list causes BUG_ON in function skb_segment

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On 07/28/2015 04:53 PM, Zhangjie (HZ) wrote:

Hi,

I generate a skb as follows:

It has a linear data region, 17 frags and the last fragment is in
skb_shinfo(skb)->frag_list.

Before this skb is sent to driver, dev_hard_start_xmit() will segment
it first(skb has frag_list,

so we get true from netif_needs_gso()), then the skb is passed to
function skb_segment().

Then, BUG_ON() happened.

while (pos < offset + len) {

        if (i >= nfrags) {

                BUG_ON(skb_headlen(list_skb));    (skbuff.c:3120)

                …

        }

        …

}

A skb that has no frags but frag_list also causes BUG_ON().

I wonder if skb like follows is legal? Could skb in frag_list have
linear data region?

 

 

Thanks

Zhangjie