From 05e8689c9a3a208bf75b60662778d81e23eac460 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sun, 1 Nov 2009 19:45:16 +0000
Subject: ifb: RCU locking avoids touching dev refcount

Avoids touching dev refcount in hotpath

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
index 030913f..69c2566 100644
--- a/drivers/net/ifb.c
+++ b/drivers/net/ifb.c
@@ -98,13 +98,15 @@ static void ri_tasklet(unsigned long dev)
 		stats->tx_packets++;
 		stats->tx_bytes +=skb->len;
 
-		skb->dev = dev_get_by_index(&init_net, skb->iif);
+		rcu_read_lock();
+		skb->dev = dev_get_by_index_rcu(&init_net, skb->iif);
 		if (!skb->dev) {
+			rcu_read_unlock();
 			dev_kfree_skb(skb);
 			stats->tx_dropped++;
 			break;
 		}
-		dev_put(skb->dev);
+		rcu_read_unlock();
 		skb->iif = _dev->ifindex;
 
 		if (from & AT_EGRESS) {
-- 
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