mac80211: support hardware TX fragmentation offload

The lower driver is notified when the fragmentation threshold changes
and upon a reconfig of the interface.

If the driver supports hardware TX fragmentation, don't fragment
packets in the stack.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 96c594309506..b392876af7d8 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1033,6 +1033,7 @@ static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
         struct ieee80211_radiotap_header *rthdr =
                 (struct ieee80211_radiotap_header *) skb->data;
         struct ieee80211_supported_band *sband;
+        bool hw_frag;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
         int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,
                                                    NULL);
@@ -1042,6 +1043,9 @@ static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
         info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
         tx->flags &= ~IEEE80211_TX_FRAGMENTED;
 
+        /* packet is fragmented in HW if we have a non-NULL driver callback */
+        hw_frag = (tx->local->ops->set_frag_threshold != NULL);
+
         /*
          * for every radiotap entry that is present
          * (ieee80211_radiotap_iterator_next returns -ENOENT when no more
@@ -1078,7 +1082,8 @@ static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
                         }
                         if (*iterator.this_arg & IEEE80211_RADIOTAP_F_WEP)
                                 info->flags &= ~IEEE80211_TX_INTFL_DONT_ENCRYPT;
-                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG)
+                        if ((*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG) &&
+                                                                !hw_frag)
                                 tx->flags |= IEEE80211_TX_FRAGMENTED;
                         break;
 
@@ -1181,8 +1186,10 @@ ieee80211_tx_prepare(struct ieee80211_sub_if_data *sdata,
         /*
          * Set this flag (used below to indicate "automatic fragmentation"),
          * it will be cleared/left by radiotap as desired.
+         * Only valid when fragmentation is done by the stack.
          */
-        tx->flags |= IEEE80211_TX_FRAGMENTED;
+        if (!local->ops->set_frag_threshold)
+                tx->flags |= IEEE80211_TX_FRAGMENTED;
 
         /* process and remove the injection radiotap header */
         if (unlikely(info->flags & IEEE80211_TX_INTFL_HAS_RADIOTAP)) {