diff options
Diffstat (limited to 'package/kernel/mac80211/patches/subsys/370-mac80211-fix-TXQ-AC-confusion.patch')
| -rw-r--r-- | package/kernel/mac80211/patches/subsys/370-mac80211-fix-TXQ-AC-confusion.patch | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/subsys/370-mac80211-fix-TXQ-AC-confusion.patch b/package/kernel/mac80211/patches/subsys/370-mac80211-fix-TXQ-AC-confusion.patch new file mode 100644 index 0000000000..0b7c8dd49b --- /dev/null +++ b/package/kernel/mac80211/patches/subsys/370-mac80211-fix-TXQ-AC-confusion.patch @@ -0,0 +1,61 @@ +From: Johannes Berg <johannes.berg@intel.com> +Date: Tue, 23 Mar 2021 21:05:01 +0100 +Subject: [PATCH] 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") +Signed-off-by: Johannes Berg <johannes.berg@intel.com> +--- + +--- a/net/mac80211/tx.c ++++ b/net/mac80211/tx.c +@@ -3589,7 +3589,7 @@ 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; + } |