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Commit 680a0dab authored Apr 13, 2015 by Johannes Berg

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>

parent 2d981fdd

include/net/mac80211.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -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-

net/mac80211/main.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

net/mac80211/tx.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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.