netdev - [PATCH] neigh: error out pending skbs if netlink invalidates incomplete neigh

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Message-Id: <1244104855-2129-1-git-send-email-timo.teras@iki.fi>
Date:	Thu,  4 Jun 2009 11:40:55 +0300
From:	Timo Teras <timo.teras@....fi>
To:	netdev@...r.kernel.org
Cc:	Timo Teras <timo.teras@....fi>
Subject: [PATCH] neigh: error out pending skbs if netlink invalidates incomplete neigh

The state transition code from incomplete to invalid via neigh_update()
is missing the proper clean up of skb queue. Separate the clean up
code from neigh_timer_handler() to a new function and make neigh_update()
is it also.

Signed-off-by: Timo Teras <timo.teras@....fi>
---
 net/core/neighbour.c |   46 ++++++++++++++++++++++++++++------------------
 1 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index a1cbce7..a17cb9d 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -771,6 +771,28 @@ static __inline__ int neigh_max_probes(struct neighbour *n)
 		p->ucast_probes + p->app_probes + p->mcast_probes);
 }
 
+static void neigh_invalidate(struct neighbour *neigh)
+{
+	struct sk_buff *skb;
+
+	NEIGH_CACHE_STAT_INC(neigh->tbl, res_failed);
+	NEIGH_PRINTK2("neigh %p is failed.\n", neigh);
+	neigh->updated = jiffies;
+
+	/* It is very thin place. report_unreachable is very complicated
+	   routine. Particularly, it can hit the same neighbour entry!
+
+	   So that, we try to be accurate and avoid dead loop. --ANK
+	 */
+	while (neigh->nud_state == NUD_FAILED &&
+	       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {
+		write_unlock(&neigh->lock);
+		neigh->ops->error_report(neigh, skb);
+		write_lock(&neigh->lock);
+	}
+	skb_queue_purge(&neigh->arp_queue);
+}
+
 /* Called when a timer expires for a neighbour entry. */
 
 static void neigh_timer_handler(unsigned long arg)
@@ -835,26 +857,9 @@ static void neigh_timer_handler(unsigned long arg)
 
 	if ((neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) &&
 	    atomic_read(&neigh->probes) >= neigh_max_probes(neigh)) {
-		struct sk_buff *skb;
-
 		neigh->nud_state = NUD_FAILED;
-		neigh->updated = jiffies;
 		notify = 1;
-		NEIGH_CACHE_STAT_INC(neigh->tbl, res_failed);
-		NEIGH_PRINTK2("neigh %p is failed.\n", neigh);
-
-		/* It is very thin place. report_unreachable is very complicated
-		   routine. Particularly, it can hit the same neighbour entry!
-
-		   So that, we try to be accurate and avoid dead loop. --ANK
-		 */
-		while (neigh->nud_state == NUD_FAILED &&
-		       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {
-			write_unlock(&neigh->lock);
-			neigh->ops->error_report(neigh, skb);
-			write_lock(&neigh->lock);
-		}
-		skb_queue_purge(&neigh->arp_queue);
+		neigh_invalidate(neigh);
 	}
 
 	if (neigh->nud_state & NUD_IN_TIMER) {
@@ -1001,6 +1006,11 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
 		neigh->nud_state = new;
 		err = 0;
 		notify = old & NUD_VALID;
+		if ((old & (NUD_INCOMPLETE | NUD_PROBE)) &&
+		    (new & NUD_FAILED)) {
+			neigh_invalidate(neigh);
+			notify = 1;
+		}
 		goto out;
 	}
 
-- 
1.6.0.4

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