On Thu, 2014-02-27 at 13:51 -0800, Ben Greear wrote:

That said, the code below appears to work, even if it is
not as efficient as it might be?

			if (msdu_chaining) {
				struct sk_buff *next = msdu_head->next;
				struct sk_buff *to_free = next;
				int space;
				static int do_once = 1;
				msdu_head->next = NULL;

				if (unlikely(do_once)) {
					ath10k_warn("htt rx msdu_chaining detected %d\n",
						    msdu_chaining);
					do_once = 0;
				}

				while (next) {
					space = next->len - skb_tailroom(msdu_head);

					if ((space > 0) &&
					    (pskb_expand_head(msdu_head, 0, space, GFP_ATOMIC) < 0)) {
						/* TODO:  bump some rx-oom error stat */
						goto outside_continue;
					}
					skb_copy_from_linear_data(next, skb_put(msdu_head, next->len),
								  next->len);
					next = next->next;
				}

Yep, this is very inefficient , you might copy data very often in
pskb_expand_head(), then in skb_copy_from_linear_data()

Also, if total length is big, you end up doing high order allocations,
since you generate a linear skb. This might fail under memory pressure.

What is the maximal skb->len of resulting skb ?