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mac80211: merge pending fixes for tx queueing issues

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Fixes a potential deadlock and a tx queue hang on STA assoc

Signed-off-by: Felix Fietkau <nbd@nbd.name>
(cherry picked from commit 8b06e06832ebe757246582b65306ad2a2537741f)
This commit is contained in:
Felix Fietkau 2022-09-15 16:38:18 +02:00 committed by Tianling Shen
parent 1dcf970839
commit cc43824357
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2 changed files with 87 additions and 0 deletions
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40
package/kernel/mac80211/patches/subsys/341-mac80211-Fix-deadlock-Don-t-start-TX-while-holding-f.patch Normal file
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@ -0,0 +1,40 @@
From: Alexander Wetzel <alexander@wetzel-home.de>
Date: Thu, 15 Sep 2022 14:41:20 +0200
Subject: [PATCH] mac80211: Fix deadlock: Don't start TX while holding
fq->lock
ieee80211_txq_purge() calls fq_tin_reset() and
ieee80211_purge_tx_queue(); Both are then calling
ieee80211_free_txskb(). Which can decide to TX the skb again.
There are at least two ways to get a deadlock:
1) When we have a TDLS teardown packet queued in either tin or frags
ieee80211_tdls_td_tx_handle() will call ieee80211_subif_start_xmit()
while we still hold fq->lock. ieee80211_txq_enqueue() will thus
deadlock.
2) A variant of the above happens if aggregation is up and running:
In that case ieee80211_iface_work() will deadlock with the original
task: The original tasks already holds fq->lock and tries to get
sta->lock after kicking off ieee80211_iface_work(). But the worker
can get sta->lock prior to the original task and will then spin for
fq->lock.
Avoid these deadlocks by not sending out any skbs when called via
ieee80211_free_txskb().
Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
---
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -698,7 +698,7 @@ static void ieee80211_report_used_skb(st
if (!sdata) {
skb->dev = NULL;
- } else {
+ } else if (!dropped) {
unsigned int hdr_size =
ieee80211_hdrlen(hdr->frame_control);

47
package/kernel/mac80211/patches/subsys/342-mac80211-Ensure-vif-queues-are-operational-after-sta.patch Normal file
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From: Alexander Wetzel <alexander@wetzel-home.de>
Date: Thu, 15 Sep 2022 15:09:46 +0200
Subject: [PATCH] mac80211: Ensure vif queues are operational after start
Make sure local->queue_stop_reasons and vif.txqs_stopped stay in sync.
When a new vif is created the queues may end up in an inconsistent state
and be inoperable:
Communication not using iTXQ will work, allowing to e.g. complete the
association. But the 4-way handshake will time out. The sta will not
send out any skbs queued in iTXQs.
All normal attempts to start the queues will fail when reaching this
state.
local->queue_stop_reasons will have marked all queues as operational but
vif.txqs_stopped will still be set, creating an inconsistent internal
state.
In reality this seems to be race between the mac80211 function
ieee80211_do_open() setting SDATA_STATE_RUNNING and the wake_txqs_tasklet:
Depending on the driver and the timing the queues may end up to be
operational or not.
Cc: stable@vger.kernel.org
Fixes: f856373e2f31 ("wifi: mac80211: do not wake queues on a vif that is being stopped")
Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
---
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -301,14 +301,14 @@ static void __ieee80211_wake_txqs(struct
local_bh_disable();
spin_lock(&fq->lock);
+ sdata->vif.txqs_stopped[ac] = false;
+
if (!test_bit(SDATA_STATE_RUNNING, &sdata->state))
goto out;
if (sdata->vif.type == NL80211_IFTYPE_AP)
ps = &sdata->bss->ps;
- sdata->vif.txqs_stopped[ac] = false;
-
list_for_each_entry_rcu(sta, &local->sta_list, list) {
if (sdata != sta->sdata)
continue;