Commit c70f59a2 authored by Ido Yariv's avatar Ido Yariv Committed by Johannes Berg
Browse files

mac80211: don't resize skbs needlessly 



Header-less cloned skbs with sufficient headroom need not be cloned
unless the tailroom is going to be modified.

Fix ieee80211_skb_resize so it would only resize cloned skbs if either
the header isn't released or the tailroom is going to be modified.

Some drivers might have assumed that skbs are never cloned, so add a HW
flag that explicitly permits cloned TX skbs. Drivers which do not modify
TX skbs should set this flag to avoid copying skbs.

Signed-off-by: default avatarIdo Yariv <idox.yariv@intel.com>
Signed-off-by: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent ca34e3b5

include/net/mac80211.h

+4 −1
Original line number Diff line number Diff line
@@ -1609,6 +1609,9 @@ struct ieee80211_tx_control { 
 *	is not enabled the default action is to disconnect when getting the

 *	CSA frame.

 *

 * @IEEE80211_HW_SUPPORTS_CLONED_SKBS: The driver will never modify the payload

 *	or tailroom of TX skbs without copying them first.

 *

 * @IEEE80211_SINGLE_HW_SCAN_ON_ALL_BANDS: The HW supports scanning on all bands

 *	in one command, mac80211 doesn't have to run separate scans per band.

 */
@@ -1642,7 +1645,7 @@ enum ieee80211_hw_flags { 
	IEEE80211_HW_TIMING_BEACON_ONLY			= 1<<26,

	IEEE80211_HW_SUPPORTS_HT_CCK_RATES		= 1<<27,

	IEEE80211_HW_CHANCTX_STA_CSA			= 1<<28,

	/* bit 29 unused */

	IEEE80211_HW_SUPPORTS_CLONED_SKBS		= 1<<29,

	IEEE80211_SINGLE_HW_SCAN_ON_ALL_BANDS		= 1<<30,

};

net/mac80211/tx.c

+4 −1
Original line number Diff line number Diff line
@@ -1478,7 +1478,10 @@ static int ieee80211_skb_resize(struct ieee80211_sub_if_data *sdata, 
		tail_need = max_t(int, tail_need, 0);

	}



	if (skb_cloned(skb))

	if (skb_cloned(skb) &&

	    (!(local->hw.flags & IEEE80211_HW_SUPPORTS_CLONED_SKBS) ||

	     !skb_clone_writable(skb, ETH_HLEN) ||

	     sdata->crypto_tx_tailroom_needed_cnt))

		I802_DEBUG_INC(local->tx_expand_skb_head_cloned);

	else if (head_need || tail_need)

		I802_DEBUG_INC(local->tx_expand_skb_head);

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