Hello, I am working on a patch to the TCP-code that, among others, share fragments between skbs, and have encountered a problem that I'm not sure if I have solved correctly.
To share a fragment, I copy the skb_frag-struct to the correct place in the other skbs frags-array, increase the page-counter, skb->data_len, skb->len, skb->end_seq and gso_segs/gso_size, and calculate a new checksum. The problem is the skb->truesize-variable. Currently I do not increase it, leading to a SKB BUG because truesize is less than (skb->len + sizeof(struct skb)). When I increase/decrease truesize, both the wmem_queue and sk_forward_alloc is something else than zero and the socket leaks memory. The kernel does not halt and all the data is received correctly in both cases. The reason that I currently don't increase/decrease truesize is that, at least if I have understod the code correctly, truesize says something about how much memory an skb actually consumes. And since I only copy existing fragments into it, I don't use any more memory. Is this correct, or should I increase/decrease truesize as well? Also, is there a better way to share fragments between skbs? Thanks in advance for any replies, Kristian -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
