mac80211: allow drivers to support S/G

If drivers want to support S/G (really just gather DMA on TX) then
we can now easily support this on the fast-xmit path since it just
needs to write to the ethernet header (and already has a check for
that being possible.)

However, disallow this on the regular TX path (which has to handle
fragmentation, software crypto, etc.) by calling skb_linearize().

Also allow the related HIGHDMA since that's not interesting to the
code in mac80211 at all anyway.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 9001bd6..0af7464 100644 (file)
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1942,8 +1942,8 @@ enum ieee80211_hw_flags {
  *     Use the %IEEE80211_RADIOTAP_VHT_KNOWN_* values.
  *
  * @netdev_features: netdev features to be set in each netdev created
- *     from this HW. Note only HW checksum features are currently
- *     compatible with mac80211. Other feature bits will be rejected.
+ *     from this HW. Note that not all features are usable with mac80211,
+ *     other features will be rejected during HW registration.
  *
  * @uapsd_queues: This bitmap is included in (re)association frame to indicate
  *     for each access category if it is uAPSD trigger-enabled and delivery-

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index df3051d..6dd6dd4 100644 (file)
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -840,7 +840,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 
        /* Only HW csum features are currently compatible with mac80211 */
        feature_whitelist = NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
-                           NETIF_F_HW_CSUM;
+                           NETIF_F_HW_CSUM | NETIF_F_SG | NETIF_F_HIGHDMA;
        if (WARN_ON(hw->netdev_features & ~feature_whitelist))
                return -EINVAL;
 

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 20a90b1..3a421a0 100644 (file)
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2864,6 +2864,12 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                        goto out;
        }
 
+       /* we cannot process non-linear frames on this path */
+       if (skb_linearize(skb)) {
+               kfree_skb(skb);
+               goto out;
+       }
+
        /* the frame could be fragmented, software-encrypted, and other things
         * so we cannot really handle checksum offload with it - fix it up in
         * software before we handle anything else.