diff options
author | Johannes Berg <johannes.berg@intel.com> | 2021-03-23 21:05:01 +0100 |
---|---|---|
committer | Johannes Berg <johannes.berg@intel.com> | 2021-04-08 10:14:48 +0200 |
commit | 1153a74768a9212daadbb50767aa400bc6a0c9b0 (patch) | |
tree | 79a20af8abb46961fdc50d4ddc09c8bfc8c8b3f1 /net | |
parent | 71826654ce40112f0651b6f4e94c422354f4adb6 (diff) |
mac80211: fix TXQ AC confusion
Normally, TXQs have
txq->tid = tid;
txq->ac = ieee80211_ac_from_tid(tid);
However, the special management TXQ actually has
txq->tid = IEEE80211_NUM_TIDS; // 16
txq->ac = IEEE80211_AC_VO;
This makes sense, but ieee80211_ac_from_tid(16) is the same
as ieee80211_ac_from_tid(0) which is just IEEE80211_AC_BE.
Now, normally this is fine. However, if the netdev queues
were stopped, then the code in ieee80211_tx_dequeue() will
propagate the stop from the interface (vif->txqs_stopped[])
if the AC 2 (ieee80211_ac_from_tid(txq->tid)) is marked as
stopped. On wake, however, __ieee80211_wake_txqs() will wake
the TXQ if AC 0 (txq->ac) is woken up.
If a driver stops all queues with ieee80211_stop_tx_queues()
and then wakes them again with ieee80211_wake_tx_queues(),
the ieee80211_wake_txqs() tasklet will run to resync queue
and TXQ state. If all queues were woken, then what'll happen
is that _ieee80211_wake_txqs() will run in order of HW queues
0-3, typically (and certainly for iwlwifi) corresponding to
ACs 0-3, so it'll call __ieee80211_wake_txqs() for each AC in
order 0-3.
When __ieee80211_wake_txqs() is called for AC 0 (VO) that'll
wake up the management TXQ (remember its tid is 16), and the
driver's wake_tx_queue() will be called. That tries to get a
frame, which will immediately *stop* the TXQ again, because
now we check against AC 2, and AC 2 hasn't yet been marked as
woken up again in sdata->vif.txqs_stopped[] since we're only
in the __ieee80211_wake_txqs() call for AC 0.
Thus, the management TXQ will never be started again.
Fix this by checking txq->ac directly instead of calculating
the AC as ieee80211_ac_from_tid(txq->tid).
Fixes: adf8ed01e4fd ("mac80211: add an optional TXQ for other PS-buffered frames")
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20210323210500.bf4d50afea4a.I136ffde910486301f8818f5442e3c9bf8670a9c4@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net')
-rw-r--r-- | net/mac80211/tx.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 5d06de61047a..3b3bcefbf657 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -3573,7 +3573,7 @@ begin: test_bit(IEEE80211_TXQ_STOP_NETIF_TX, &txqi->flags)) goto out; - if (vif->txqs_stopped[ieee80211_ac_from_tid(txq->tid)]) { + if (vif->txqs_stopped[txq->ac]) { set_bit(IEEE80211_TXQ_STOP_NETIF_TX, &txqi->flags); goto out; } |