mac80211: fix potentially redundant skb data copying

When an skb is shared, it needs to be duplicated, along with its data buffer.
If the skb does not have enough headroom, using skb_copy might cause the data
buffer to be copied twice (once by skb_copy and once by pskb_expand_head).
Fix this by using skb_clone initially and letting ieee80211_skb_resize sort
out the rest.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 90ee235500332e9df881388669d128a36c283e53..d2b4b67a7b53d425e2767185f22a78dbd34c78a2 100644 (file)
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1934,7 +1934,7 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
         */
        if (skb_shared(skb)) {
                tmp_skb = skb;
-               skb = skb_copy(skb, GFP_ATOMIC);
+               skb = skb_clone(skb, GFP_ATOMIC);
                kfree_skb(tmp_skb);
 
                if (!skb) {