[PATCH v2] mac80211: allow low-level drivers to set netdev feature bits

[Arik Nemtsov <arik@wizery.com>]

Low level drivers can now set certain netdev feature bits in
netdev_features member of the ieee80211_hw struct. These will be
propagated to every netdev created from this HW.

The white-listed features currently include only ones related to HW
checksumming.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
---
 include/net/mac80211.h |    9 +++++++--
 net/mac80211/iface.c   |    2 ++
 net/mac80211/main.c    |    9 +++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 4d6e6c6..b0a2cc8 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1286,8 +1286,12 @@ enum ieee80211_hw_flags {
  *	aggregate an HT driver will transmit, used by the peer as a
  *	hint to size its reorder buffer.
  *
- * @offchannel_tx_hw_queue: HW queue ID to use for offchannel TX
- *	(if %IEEE80211_HW_QUEUE_CONTROL is set)
+ * @offchannel_tx_hw_queue: hw queue id to use for offchannel tx
+ *	(if %ieee80211_hw_queue_control is set)
+ *
+ * @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.
  */
 struct ieee80211_hw {
 	struct ieee80211_conf conf;
@@ -1309,6 +1313,7 @@ struct ieee80211_hw {
 	u8 max_rx_aggregation_subframes;
 	u8 max_tx_aggregation_subframes;
 	u8 offchannel_tx_hw_queue;
+	netdev_features_t netdev_features;
 };
 
 /**
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 3e05a8b..c2ad78a 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1350,6 +1350,8 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 			sdata->u.mgd.use_4addr = params->use_4addr;
 	}
 
+	ndev->features |= local->hw.netdev_features;
+
 	ret = register_netdevice(ndev);
 	if (ret)
 		goto fail;
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index b70f7f0..648a741 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -679,6 +679,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	enum ieee80211_band band;
 	int channels, max_bitrates;
 	bool supp_ht;
+	netdev_features_t feature_whitelist;
 	static const u32 cipher_suites[] = {
 		/* keep WEP first, it may be removed below */
 		WLAN_CIPHER_SUITE_WEP40,
@@ -705,6 +706,14 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	if ((hw->flags & IEEE80211_HW_SCAN_WHILE_IDLE) && !local->ops->hw_scan)
 		return -EINVAL;
 
+	/* Only HW csum features are currently compatible with mac80211 */
+	feature_whitelist = NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
+			    NETIF_F_HW_CSUM;
+	if (hw->netdev_features & ~feature_whitelist) {
+		WARN(1, "HW netdev features not supported by mac80211");
+		return -EINVAL;
+	}
+
 	if (hw->max_report_rates == 0)
 		hw->max_report_rates = hw->max_rates;
 
-- 
1.7.9.5