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>

1 files changed, 4 insertions, 0 deletions

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);
         }