From 915219441d566f1da0caa0e262be49b666159e17 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 28 May 2009 21:35:47 -0700 Subject: tcp: Use SKB queue and list helpers instead of doing it by-hand. Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 118 ++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 83 insertions(+), 35 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eeb8a92aa41..ba34a23c1bf 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4426,7 +4426,7 @@ drop: } __skb_queue_head(&tp->out_of_order_queue, skb); } else { - struct sk_buff *skb1 = tp->out_of_order_queue.prev; + struct sk_buff *skb1 = skb_peek_tail(&tp->out_of_order_queue); u32 seq = TCP_SKB_CB(skb)->seq; u32 end_seq = TCP_SKB_CB(skb)->end_seq; @@ -4443,15 +4443,18 @@ drop: } /* Find place to insert this segment. */ - do { + while (1) { if (!after(TCP_SKB_CB(skb1)->seq, seq)) break; - } while ((skb1 = skb1->prev) != - (struct sk_buff *)&tp->out_of_order_queue); + if (skb_queue_is_first(&tp->out_of_order_queue, skb1)) { + skb1 = NULL; + break; + } + skb1 = skb_queue_prev(&tp->out_of_order_queue, skb1); + } /* Do skb overlap to previous one? */ - if (skb1 != (struct sk_buff *)&tp->out_of_order_queue && - before(seq, TCP_SKB_CB(skb1)->end_seq)) { + if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) { if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) { /* All the bits are present. Drop. */ __kfree_skb(skb); @@ -4463,24 +4466,41 @@ drop: tcp_dsack_set(sk, seq, TCP_SKB_CB(skb1)->end_seq); } else { - skb1 = skb1->prev; + if (skb_queue_is_first(&tp->out_of_order_queue, + skb1)) + skb1 = NULL; + else + skb1 = skb_queue_prev( + &tp->out_of_order_queue, + skb1); } } - __skb_queue_after(&tp->out_of_order_queue, skb1, skb); + if (!skb1) + __skb_queue_head(&tp->out_of_order_queue, skb); + else + __skb_queue_after(&tp->out_of_order_queue, skb1, skb); /* And clean segments covered by new one as whole. */ - while ((skb1 = skb->next) != - (struct sk_buff *)&tp->out_of_order_queue && - after(end_seq, TCP_SKB_CB(skb1)->seq)) { - if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) { + if (skb1 && !skb_queue_is_last(&tp->out_of_order_queue, skb1)) { + struct sk_buff *n; + + 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); tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq, - end_seq); - break; + TCP_SKB_CB(skb1)->end_seq); + __kfree_skb(skb1); } - __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: @@ -4492,7 +4512,10 @@ add_sack: static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb, struct sk_buff_head *list) { - struct sk_buff *next = skb->next; + struct sk_buff *next = NULL; + + if (!skb_queue_is_last(list, skb)) + next = skb_queue_next(list, skb); __skb_unlink(skb, list); __kfree_skb(skb); @@ -4503,6 +4526,9 @@ static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb, /* Collapse contiguous sequence of skbs head..tail with * sequence numbers start..end. + * + * If tail is NULL, this means until the end of the list. + * * Segments with FIN/SYN are not collapsed (only because this * simplifies code) */ @@ -4511,15 +4537,23 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct sk_buff *head, struct sk_buff *tail, u32 start, u32 end) { - struct sk_buff *skb; + struct sk_buff *skb, *n; + bool end_of_skbs; /* First, check that queue is collapsible and find * the point where collapsing can be useful. */ - for (skb = head; skb != tail;) { + skb = head; +restart: + end_of_skbs = true; + skb_queue_walk_from_safe(list, skb, n) { + if (skb == tail) + break; /* No new bits? It is possible on ofo queue. */ if (!before(start, TCP_SKB_CB(skb)->end_seq)) { skb = tcp_collapse_one(sk, skb, list); - continue; + if (!skb) + break; + goto restart; } /* The first skb to collapse is: @@ -4529,16 +4563,24 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, */ if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin && (tcp_win_from_space(skb->truesize) > skb->len || - before(TCP_SKB_CB(skb)->seq, start) || - (skb->next != tail && - TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb->next)->seq))) + before(TCP_SKB_CB(skb)->seq, start))) { + end_of_skbs = false; break; + } + + if (!skb_queue_is_last(list, skb)) { + struct sk_buff *next = skb_queue_next(list, skb); + if (next != tail && + TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(next)->seq) { + end_of_skbs = false; + break; + } + } /* Decided to skip this, advance start seq. */ start = TCP_SKB_CB(skb)->end_seq; - skb = skb->next; } - if (skb == tail || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin) + if (end_of_skbs || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin) return; while (before(start, end)) { @@ -4583,7 +4625,8 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, } if (!before(start, TCP_SKB_CB(skb)->end_seq)) { skb = tcp_collapse_one(sk, skb, list); - if (skb == tail || + if (!skb || + skb == tail || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin) return; @@ -4610,17 +4653,21 @@ static void tcp_collapse_ofo_queue(struct sock *sk) head = skb; for (;;) { - skb = skb->next; + struct sk_buff *next = NULL; + + if (!skb_queue_is_last(&tp->out_of_order_queue, skb)) + next = skb_queue_next(&tp->out_of_order_queue, skb); + skb = next; /* Segment is terminated when we see gap or when * we are at the end of all the queue. */ - if (skb == (struct sk_buff *)&tp->out_of_order_queue || + if (!skb || after(TCP_SKB_CB(skb)->seq, end) || before(TCP_SKB_CB(skb)->end_seq, start)) { tcp_collapse(sk, &tp->out_of_order_queue, head, skb, start, end); head = skb; - if (skb == (struct sk_buff *)&tp->out_of_order_queue) + if (!skb) break; /* Start new segment */ start = TCP_SKB_CB(skb)->seq; @@ -4681,10 +4728,11 @@ static int tcp_prune_queue(struct sock *sk) tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss); tcp_collapse_ofo_queue(sk); - tcp_collapse(sk, &sk->sk_receive_queue, - sk->sk_receive_queue.next, - (struct sk_buff *)&sk->sk_receive_queue, - tp->copied_seq, tp->rcv_nxt); + if (!skb_queue_empty(&sk->sk_receive_queue)) + tcp_collapse(sk, &sk->sk_receive_queue, + skb_peek(&sk->sk_receive_queue), + NULL, + tp->copied_seq, tp->rcv_nxt); sk_mem_reclaim(sk); if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) -- cgit v1.2.3-70-g09d2 From 2df9001edc382c331f338f45d259feeaa740c418 Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Fri, 29 May 2009 15:02:29 -0700 Subject: tcp: fix loop in ofo handling code and reduce its complexity MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ba34a23c1bf..2bdb0da237e 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: -- cgit v1.2.3-70-g09d2