Hi Alex,
On 16/09/14 21:07, Alexander Aring wrote:
On Tue, Sep 16, 2014 at 08:53:06PM +0100, Martin Townsend wrote:
...
I make another c example, hopeful more correct than the last one:
char *foo(char *skb)
{
char *new;
if (some_error_before_consume)
return ERR_PTR(-EINVAL); /* here we need to do a free(skb) */
/* UDP expand */
new = expand(skb, 16);
s/16/8 , argl, doesn't matter was only an example. :-)
if (!new)
return ERR_PTR(-ENOMEM);
consume(skb); /* parameter skb becomes dangling pointer */
skb = new; /* doesn't rescue it, it is different than skb from caller function
at this point, the skb_inout had rescue it, because it was a pointer
of pointer */
/* IPv6 expand */
new = expand(skb, 40);
if (!new) /* some error after a consume(skb), will crash at drop_skb label */
return ERR_PTR(-ENOMEM);
consume(skb);
skb = new;
return skb;
}
I see the problem now, once the skb has been copied and then an error occurs
you have to return the error and the skb has been lost. Would using the
skb->cb to store decompress status get around this problem?
mhhh, complicated... on 802.15.4 6LoWPAN we use the control block
information for fragmentation information. I don't know right now if we
get trouble when we add the "uncompression on the fly when FRAG1 was
received".
What exactly do you mean with "decompress status"?
An integer that either contains an error code or 0 that process_data
would set as process_data is now IPHC decompression.
- Alex
- Martin.
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