From 2df9001edc382c331f338f45d259feeaa740c418 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Fri, 29 May 2009 15:02:29 -0700 Subject: [PATCH] tcp: fix loop in ofo handling code and reduce its complexity MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Somewhat luckily, I was looking into these parts with very fine comb because I've made somewhat similar changes on the same area (conflicts that arose weren't that lucky though). The loop was very much overengineered recently in commit 915219441d566 (tcp: Use SKB queue and list helpers instead of doing it by-hand), while it basically just wants to know if there are skbs after 'skb'. Also it got broken because skb1 = skb->next got translated into skb1 = skb1->next (though abstracted) improperly. Note that 'skb1' is pointing to previous sk_buff than skb or NULL if at head. Two things went wrong: - We'll kfree 'skb' on the first iteration instead of the skbuff following 'skb' (it would require required SACK reneging to recover I think). - The list head case where 'skb1' is NULL is checked too early and the loop won't execute whereas it previously did. Conclusion, mostly revert the recent changes which makes the cset very messy looking but using proper accessor in the previous-like version. The effective changes against the original can be viewed with: git-diff 915219441d566f1da0caa0e262be49b666159e17^ \ net/ipv4/tcp_input.c | sed -n -e '57,70 p' Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ba34a23c1bfb..2bdb0da237e6 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4481,26 +4481,20 @@ drop: __skb_queue_after(&tp->out_of_order_queue, skb1, skb); /* And clean segments covered by new one as whole. */ - if (skb1 && !skb_queue_is_last(&tp->out_of_order_queue, skb1)) { - struct sk_buff *n; + while (!skb_queue_is_last(&tp->out_of_order_queue, skb)) { + skb1 = skb_queue_next(&tp->out_of_order_queue, skb); - skb1 = skb_queue_next(&tp->out_of_order_queue, skb1); - skb_queue_walk_from_safe(&tp->out_of_order_queue, - skb1, n) { - if (!after(end_seq, TCP_SKB_CB(skb1)->seq)) - break; - if (before(end_seq, - TCP_SKB_CB(skb1)->end_seq)) { - tcp_dsack_extend(sk, - TCP_SKB_CB(skb1)->seq, - end_seq); - break; - } - __skb_unlink(skb1, &tp->out_of_order_queue); + if (!after(end_seq, TCP_SKB_CB(skb1)->seq)) + break; + if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) { tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq, - TCP_SKB_CB(skb1)->end_seq); - __kfree_skb(skb1); + end_seq); + break; } + __skb_unlink(skb1, &tp->out_of_order_queue); + tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq, + TCP_SKB_CB(skb1)->end_seq); + __kfree_skb(skb1); } add_sack: -- 2.20.1