netdev - [PATCH net-next 8/8] net: mac80211: use skb_list_walk

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Date:   Mon, 13 Jan 2020 18:42:33 -0500
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     davem@...emloft.net, johannes@...solutions.net,
        netdev@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH net-next 8/8] net: mac80211: use skb_list_walk_safe helper for gso segments

This is a conversion case for the new function, keeping the flow of the
existing code as intact as possible. We also switch over to using
skb_mark_not_on_list instead of a null write to skb->next.

Finally, this code appeared to have a memory leak in the case where
header building fails before the last gso segment. In that case, the
remaining segments are not freed. So this commit also adds the proper
kfree_skb_list call for the remainder of the skbs.

Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 net/mac80211/tx.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index a8a7306a1f56..4bd1faf4f779 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3949,18 +3949,15 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 		}
 	}
 
-	next = skb;
-	while (next) {
-		skb = next;
-		next = skb->next;
-
-		skb->prev = NULL;
-		skb->next = NULL;
+	skb_list_walk_safe(skb, skb, next) {
+		skb_mark_not_on_list(skb);
 
 		skb = ieee80211_build_hdr(sdata, skb, info_flags,
 					  sta, ctrl_flags);
-		if (IS_ERR(skb))
+		if (IS_ERR(skb)) {
+			kfree_skb_list(next);
 			goto out;
+		}
 
 		ieee80211_tx_stats(dev, skb->len);
 
-- 
2.24.1