l2tp: fix reorder timeout recovery (38d40b3f) · Commits · 戴 / test

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 <jchapman@katalix.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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, "

net/l2tp/l2tp_core.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;

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