Re: Is this a bug from function kernel_int?

[fche at redhat dot com (Frank Ch. Eigler)]

Hi -

> [...]
>     __u32 end_seq; /* SEQ + FIN + SYN + datalen */
>
> So, end_seq is an unsigned 32-bit value, not a signed 32-bit value.
> Strangely enough, we don't have a kernel_uint() function. But, you
> could do something like:
>
>   __uint32(*kernel_int(&*@cast($skb->cb, "tcp_skb_cb",
> "kernel<net/tcp.h>")->end_seq))

Chances are you don't need that much machinery.  
A 

    probe SOMEWHERE {
       end_seq = @cast($skb->cb, "tcp_skb_cb", "kernel<net/tcp.h>")->end_seq
    }

works for me here, though I think the unsignedness of end_seq is not
specifically handled.  We should probably treat that as a systemtap bug,
but you can work around it with a

      end_seq = end_seq & 0xffffffff

- FChE