From f333a15a3eaf831067f9bfed35f1bb5fe0670b9f Mon Sep 17 00:00:00 2001
From: Tony Cheneau <tony.cheneau@amnesiak.org>
Date: Mon, 25 Mar 2013 17:59:23 +0000
Subject: [PATCH] 6lowpan: always enable link-layer acknowledgments

This feature is especially important when using fragmentation, because
the reassembly mechanism cannot recover from the loss of a fragment.

Note that some hardware ignore this flag and not will not transmit
acknowledgments even if this is set.

Signed-off-by: Tony Cheneau <tony.cheneau@amnesiak.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ieee802154/6lowpan.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 9f53904b5261..e7f61de2459a 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -584,6 +584,10 @@ static int lowpan_header_create(struct sk_buff *skb,
 
 		mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
 
+		/* request acknowledgment when possible */
+		if (!lowpan_is_addr_broadcast(daddr))
+			mac_cb(skb)->flags |= MAC_CB_FLAG_ACKREQ;
+
 		return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,
 				type, (void *)&da, (void *)&sa, skb->len);
 	}