diff mbox series

mac80211: always account for A-MSDU header changes

Message ID 20180830085549.21955-1-johannes@sipsolutions.net (mailing list archive)
State Accepted
Delegated to: Johannes Berg
Headers show
Series mac80211: always account for A-MSDU header changes | expand

Commit Message

Johannes Berg Aug. 30, 2018, 8:55 a.m. UTC 
From: Johannes Berg <johannes.berg@intel.com>

In the error path of changing the SKB headroom of the second
A-MSDU subframe, we would not account for the already-changed
length of the first frame that just got converted to be in
A-MSDU format and thus is a bit longer now.

Fix this by doing the necessary accounting.

It would be possible to reorder the operations, but that would
make the code more complex (to calculate the necessary pad),
and the headroom expansion should not fail frequently enough
to make that worthwhile.

Fixes: 6e0456b54545 ("mac80211: add A-MSDU tx support")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/mac80211/tx.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

Lorenzo Bianconi Aug. 30, 2018, 9:04 a.m. UTC | #1 
> From: Johannes Berg <johannes.berg@intel.com>
> 
> In the error path of changing the SKB headroom of the second
> A-MSDU subframe, we would not account for the already-changed
> length of the first frame that just got converted to be in
> A-MSDU format and thus is a bit longer now.
> 
> Fix this by doing the necessary accounting.
> 
> It would be possible to reorder the operations, but that would
> make the code more complex (to calculate the necessary pad),
> and the headroom expansion should not fail frequently enough
> to make that worthwhile.
> 
> Fixes: 6e0456b54545 ("mac80211: add A-MSDU tx support")
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> ---

Acked-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
diff mbox series

Patch

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 1aac5e3c7eee..6ca0865de945 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3239,7 +3239,7 @@  static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 
 	if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) +
 						     2 + pad))
-		goto out;
+		goto out_recalc;
 
 	ret = true;
 	data = skb_push(skb, ETH_ALEN + 2);
@@ -3256,11 +3256,13 @@  static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 	head->data_len += skb->len;
 	*frag_tail = skb;
 
-	flow->backlog += head->len - orig_len;
-	tin->backlog_bytes += head->len - orig_len;
-
-	fq_recalc_backlog(fq, tin, flow);
+out_recalc:
+	if (head->len != orig_len) {
+		flow->backlog += head->len - orig_len;
+		tin->backlog_bytes += head->len - orig_len;
 
+		fq_recalc_backlog(fq, tin, flow);
+	}
 out:
 	spin_unlock_bh(&fq->lock);