Commit 7c946062 authored Jan 28, 2017 by Sven Eckelmann Committed by Simon Wunderlich Jan 28, 2017

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: c3370518 ("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>

parent c3370518

net/batman-adv/send.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -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;