netdev - [net-next] neigh: remove duplicate check for same neigh

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Date:   Tue, 29 Nov 2016 16:22:51 +0800
From:   Zhang Shengju <zhangshengju@...s.chinamobile.com>
To:     netdev@...r.kernel.org, dsa@...ulusnetworks.com
Subject: [net-next] neigh: remove duplicate check for same neigh

Currently loop index 'idx' is used as the index in the neigh list of interest. 
It's increased only when the neigh is dumped. It's not the absolute index in 
the list. Because there is no info to record which neigh has already be scanned 
by previous loop. This will cause the filtered out neighs to be scanned mulitple 
times. 

This patch make idx as the absolute index in the list, it will increase no matter
whether the neigh is filtered. This will prevent the above problem.

And this is in line with other dump functions.

Signed-off-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>
---
 net/core/neighbour.c | 39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 2ae929f..ce32e9c 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2256,6 +2256,16 @@ static bool neigh_ifindex_filtered(struct net_device *dev, int filter_idx)
 	return false;
 }
 
+static bool neigh_dump_filtered(struct net_device *dev, int filter_idx,
+		int filter_master_idx)
+{
+	if (neigh_ifindex_filtered(dev, filter_idx) ||
+	    neigh_master_filtered(dev, filter_master_idx))
+		return true;
+
+	return false;
+}
+
 static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 			    struct netlink_callback *cb)
 {
@@ -2285,20 +2295,15 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 	rcu_read_lock_bh();
 	nht = rcu_dereference_bh(tbl->nht);
 
-	for (h = s_h; h < (1 << nht->hash_shift); h++) {
-		if (h > s_h)
-			s_idx = 0;
+	for (h = s_h; h < (1 << nht->hash_shift); h++, s_idx = 0) {
 		for (n = rcu_dereference_bh(nht->hash_buckets[h]), idx = 0;
 		     n != NULL;
-		     n = rcu_dereference_bh(n->next)) {
-			if (!net_eq(dev_net(n->dev), net))
-				continue;
-			if (neigh_ifindex_filtered(n->dev, filter_idx))
+		     n = rcu_dereference_bh(n->next), idx++) {
+			if (idx < s_idx || !net_eq(dev_net(n->dev), net))
 				continue;
-			if (neigh_master_filtered(n->dev, filter_master_idx))
+			if (neigh_dump_filtered(n->dev, filter_idx,
+						filter_master_idx))
 				continue;
-			if (idx < s_idx)
-				goto next;
 			if (neigh_fill_info(skb, n, NETLINK_CB(cb->skb).portid,
 					    cb->nlh->nlmsg_seq,
 					    RTM_NEWNEIGH,
@@ -2306,8 +2311,6 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 				rc = -1;
 				goto out;
 			}
-next:
-			idx++;
 		}
 	}
 	rc = skb->len;
@@ -2328,14 +2331,10 @@ static int pneigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 
 	read_lock_bh(&tbl->lock);
 
-	for (h = s_h; h <= PNEIGH_HASHMASK; h++) {
-		if (h > s_h)
-			s_idx = 0;
-		for (n = tbl->phash_buckets[h], idx = 0; n; n = n->next) {
-			if (pneigh_net(n) != net)
+	for (h = s_h; h <= PNEIGH_HASHMASK; h++, s_idx = 0) {
+		for (n = tbl->phash_buckets[h], idx = 0; n; n = n->next, idx++) {
+			if (idx < s_idx || pneigh_net(n) != net)
 				continue;
-			if (idx < s_idx)
-				goto next;
 			if (pneigh_fill_info(skb, n, NETLINK_CB(cb->skb).portid,
 					    cb->nlh->nlmsg_seq,
 					    RTM_NEWNEIGH,
@@ -2344,8 +2343,6 @@ static int pneigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 				rc = -1;
 				goto out;
 			}
-		next:
-			idx++;
 		}
 	}
 
-- 
1.8.3.1