git.openwrt.org Git - openwrt/staging/lynxis.git/blob

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Thu, 8 Mar 2018 21:00:56 +0100
   3 Subject: [PATCH] mac80211: fix memory accounting with A-MSDU aggregation
   4
   5 fq uses skb->truesize for memory usage tracking. Increments/decrements
   6 are done on enqueue/dequeue.
   7 When A-MSDU aggregation is performed on tx side, the packet is
   8 aggregated with the last packet in the queue belonging to the same flow.
   9 There are multiple bugs here:
  10 - The truesize field of the aggregated packet isn't updated, so memory
  11 usage is underestimated
  12 - fq->memory_usage isn't adjusted.
  13
  14 Because of the combination of both bugs, this only causes tx issues in
  15 rare cases, mainly when the A-MSDU head needs to be reallocated.
  16
  17 Fix this by adjusting both truesize of the A-MSDU head and adding the
  18 truesize delta to fq->memory_usage.
  19
  20 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  21 ---
  22
  23 --- a/net/mac80211/tx.c
  24 +++ b/net/mac80211/tx.c
  25 @@ -3194,6 +3194,7 @@ static bool ieee80211_amsdu_aggregate(st
  26         u8 max_subframes = sta->sta.max_amsdu_subframes;
  27         int max_frags = local->hw.max_tx_fragments;
  28         int max_amsdu_len = sta->sta.max_amsdu_len;
  29 +       int orig_truesize;
  30         __be16 len;
  31         void *data;
  32         bool ret = false;
  33 @@ -3225,12 +3226,13 @@ static bool ieee80211_amsdu_aggregate(st
  34         flow = fq_flow_classify(fq, tin, skb, fq_flow_get_default_func);
  35         head = skb_peek_tail(&flow->queue);
  36         if (!head)
  37 -               goto out;
  38 +               goto unlock;
  39
  40 +       orig_truesize = head->truesize;
  41         orig_len = head->len;
  42
  43         if (skb->len + head->len > max_amsdu_len)
  44 -               goto out;
  45 +               goto unlock;
  46
  47         nfrags = 1 + skb_shinfo(skb)->nr_frags;
  48         nfrags += 1 + skb_shinfo(head)->nr_frags;
  49 @@ -3288,6 +3290,9 @@ out_recalc:
  50                 fq_recalc_backlog(fq, tin, flow);
  51         }
  52  out:
  53 +       fq->memory_usage += head->truesize - orig_truesize;
  54 +
  55 +unlock:
  56         spin_unlock_bh(&fq->lock);
  57
  58         return ret;