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batman-adv: Fix double call of dev_queue_xmit 

The net_xmit_eval has side effects because it is not making sure that e
isn't evaluated twice.

    #define net_xmit_eval(e)        ((e) == NET_XMIT_CN ? 0 : (e))

The code requested by David Miller [1]

    return net_xmit_eval(dev_queue_xmit(skb));

will get transformed into

    return ((dev_queue_xmit(skb)) == NET_XMIT_CN ? 0 : (dev_queue_xmit(skb)))

dev_queue_xmit will therefore be tried again (with an already consumed skb)
whenever the return code is not NET_XMIT_CN.

[1] https://lkml.kernel.org/r/20170125.225624.965229145391320056.davem@davemloft.net

Fixes: c33705188c ("batman-adv: Treat NET_XMIT_CN as transmit successfully")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
This commit is contained in:
Sven Eckelmann 2017-01-28 10:12:39 +01:00 committed by Simon Wunderlich
parent c33705188c
commit 7c946062b3
1 changed files with 3 additions and 1 deletions
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4
net/batman-adv/send.c
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@ -77,6 +77,7 @@ int batadv_send_skb_packet(struct sk_buff *skb,
{
struct batadv_priv *bat_priv;
struct ethhdr *ethhdr;
int ret;
bat_priv = netdev_priv(hard_iface->soft_iface);
@ -115,7 +116,8 @@ int batadv_send_skb_packet(struct sk_buff *skb,
* congestion and traffic shaping, it drops and returns NET_XMIT_DROP
* (which is > 0). This will not be treated as an error.
*/
return net_xmit_eval(dev_queue_xmit(skb));
ret = dev_queue_xmit(skb);
return net_xmit_eval(ret);
send_skb_err:
kfree_skb(skb);
return NET_XMIT_DROP;