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authorFelix Fietkau <nbd@nbd.name>2018-03-08 21:13:25 +0100
committerFelix Fietkau <nbd@nbd.name>2018-03-10 10:20:45 +0100
commit6011f7bcf0bfab0d65fb0522de0c210565fe4e74 (patch)
tree77510e72d15ffc063357a9eec7d4711a4467447d
parentb7b14fd64e09b523b2da6a9db6d7ff300964b955 (diff)
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mac80211: fix a tx queue memory accounting error
Fixes rare hard to trigger tx hangs after some time Signed-off-by: Felix Fietkau <nbd@nbd.name>
-rw-r--r--package/kernel/mac80211/patches/378-mac80211-fix-memory-accounting-with-A-MSDU-aggregati.patch66
1 files changed, 66 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/378-mac80211-fix-memory-accounting-with-A-MSDU-aggregati.patch b/package/kernel/mac80211/patches/378-mac80211-fix-memory-accounting-with-A-MSDU-aggregati.patch
new file mode 100644
index 0000000000..af98f6162a
--- /dev/null
+++ b/package/kernel/mac80211/patches/378-mac80211-fix-memory-accounting-with-A-MSDU-aggregati.patch
@@ -0,0 +1,66 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Thu, 8 Mar 2018 21:00:56 +0100
+Subject: [PATCH] mac80211: fix memory accounting with A-MSDU aggregation
+
+fq uses skb->truesize for memory usage tracking. Increments/decrements
+are done on enqueue/dequeue.
+When A-MSDU aggregation is performed on tx side, the packet is
+aggregated with the last packet in the queue belonging to the same flow.
+There are multiple bugs here:
+- The truesize field of the aggregated packet isn't updated, so memory
+usage is underestimated
+- fq->memory_usage isn't adjusted.
+
+Because of the combination of both bugs, this only causes tx issues in
+rare cases, mainly when the A-MSDU head needs to be reallocated.
+
+Fix this by adjusting both truesize of the A-MSDU head and adding the
+truesize delta to fq->memory_usage.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3171,6 +3171,7 @@ static bool ieee80211_amsdu_aggregate(st
+ u8 max_subframes = sta->sta.max_amsdu_subframes;
+ int max_frags = local->hw.max_tx_fragments;
+ int max_amsdu_len = sta->sta.max_amsdu_len;
++ int orig_truesize;
+ __be16 len;
+ void *data;
+ bool ret = false;
+@@ -3201,12 +3202,13 @@ static bool ieee80211_amsdu_aggregate(st
+ flow = fq_flow_classify(fq, tin, skb, fq_flow_get_default_func);
+ head = skb_peek_tail(&flow->queue);
+ if (!head)
+- goto out;
++ goto unlock;
+
++ orig_truesize = head->truesize;
+ orig_len = head->len;
+
+ if (skb->len + head->len > max_amsdu_len)
+- goto out;
++ goto unlock;
+
+ if (!ieee80211_amsdu_prepare_head(sdata, fast_tx, head))
+ goto out;
+@@ -3241,6 +3243,7 @@ static bool ieee80211_amsdu_aggregate(st
+
+ head->len += skb->len;
+ head->data_len += skb->len;
++ head->truesize += skb->truesize;
+ *frag_tail = skb;
+
+ flow->backlog += head->len - orig_len;
+@@ -3249,6 +3252,9 @@ static bool ieee80211_amsdu_aggregate(st
+ fq_recalc_backlog(fq, tin, flow);
+
+ out:
++ fq->memory_usage += head->truesize - orig_truesize;
++
++unlock:
+ spin_unlock_bh(&fq->lock);
+
+ return ret;