netdev - [PATCH] ifb: should not use __dev_get_by

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Message-ID: <4ADDAEA6.2040903@gmail.com>
Date:	Tue, 20 Oct 2009 14:35:50 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org
Subject: [PATCH] ifb: should not use __dev_get_by_index() without locks

David Miller a écrit :
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Tue, 20 Oct 2009 06:23:54 +0200
> 
>> I wonder if the whole thing could use RCU somehow, since some
>> workloads hit this dev_base_lock rwlock pretty hard...
> 
> True, but for now we'll put your fix in :-)

Here is another vulnerable point, needing following patch.

Thanks

[PATCH] ifb: should not use __dev_get_by_index() without locks

At this point (ri_tasklet()), RTNL or dev_base_lock are not held,
we must use dev_get_by_index() instead of __dev_get_by_index()

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---

diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
index 801f088..030913f 100644
--- a/drivers/net/ifb.c
+++ b/drivers/net/ifb.c
@@ -98,12 +98,13 @@ 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);
+		skb->dev = dev_get_by_index(&init_net, skb->iif);
 		if (!skb->dev) {
 			dev_kfree_skb(skb);
 			stats->tx_dropped++;
 			break;
 		}
+		dev_put(skb->dev);
 		skb->iif = _dev->ifindex;
 
 		if (from & AT_EGRESS) {

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