From 38d40b3f4e223336422b7e87cb483e758ef87e3a Mon Sep 17 00:00:00 2001 From: James Chapman Date: Wed, 9 May 2012 23:43:08 +0000 Subject: [PATCH] l2tp: fix reorder timeout recovery When L2TP data packet reordering is enabled, packets are held in a queue while waiting for out-of-sequence packets. If a packet gets lost, packets will be held until the reorder timeout expires, when we are supposed to then advance to the sequence number of the next packet but we don't currently do so. As a result, the data channel is stuck because we are waiting for a packet that will never arrive - all packets age out and none are passed. The fix is to add a flag to the session context, which is set when the reorder timeout expires and tells the receive code to reset the next expected sequence number to that of the next packet in the queue. Tested in a production L2TP network with Starent and Nortel L2TP gear. Signed-off-by: James Chapman Signed-off-by: David S. Miller --- net/l2tp/l2tp_core.c | 9 +++++++++ net/l2tp/l2tp_core.h | 1 + 2 files changed, 10 insertions(+) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 456b52d8f6d8..d1ab3a236cca 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -428,6 +428,7 @@ start: session->name, L2TP_SKB_CB(skb)->ns, L2TP_SKB_CB(skb)->length, session->nr, skb_queue_len(&session->reorder_q)); + session->reorder_skip = 1; __skb_unlink(skb, &session->reorder_q); kfree_skb(skb); if (session->deref) @@ -436,6 +437,14 @@ start: } if (L2TP_SKB_CB(skb)->has_seq) { + if (session->reorder_skip) { + PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, + "%s: advancing nr to next pkt: %u -> %u", + session->name, session->nr, + L2TP_SKB_CB(skb)->ns); + session->reorder_skip = 0; + session->nr = L2TP_SKB_CB(skb)->ns; + } if (L2TP_SKB_CB(skb)->ns != session->nr) { PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, "%s: holding oos pkt %u len %d, " diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h index 0bf60fc88bb7..90026341a1e5 100644 --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -123,6 +123,7 @@ struct l2tp_session { * categories */ int reorder_timeout; /* configured reorder timeout * (in jiffies) */ + int reorder_skip; /* set if skip to next nr */ int mtu; int mru; enum l2tp_pwtype pwtype;