mac80211: Fix tx queue handling during scans

Scans currently work by stopping the netdev tx queues but leaving the
mac80211 queues active. This stops the flow of incoming packets while
still allowing mac80211 to transmit nullfunc and probe request frames to
facilitate scanning. However, the driver may try to wake the mac80211
queues while in this state, which will also wake the netdev queues.

To prevent this, add a new queue stop reason,
IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL, to be used when stopping the tx
queues for off-channel operation. This prevents the netdev queues from
waking when a driver wakes the mac80211 queues.

This also stops all frames from being transmitted, even those meant to
be sent off-channel. Add a new tx control flag,
IEEE80211_TX_CTL_OFFCHAN_TX_OK, which allows frames to be transmitted
when the queues are stopped only for the off-channel stop reason. Update
all locations transmitting off-channel frames to use this flag.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 86ad2c341525..0eaa9092364b 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -399,6 +399,9 @@ struct ieee80211_bss_conf {
  * @IEEE80211_TX_CTL_RATE_CTRL_PROBE: internal to mac80211, can be
  *      set by rate control algorithms to indicate probe rate, will
  *      be cleared for fragmented frames (except on the last fragment)
+ * @IEEE80211_TX_INTFL_OFFCHAN_TX_OK: Internal to mac80211. Used to indicate
+ *      that a frame can be transmitted while the queues are stopped for
+ *      off-channel operation.
  * @IEEE80211_TX_INTFL_NEED_TXPROCESSING: completely internal to mac80211,
  *      used to indicate that a pending frame requires TX processing before
  *      it can be sent out.
@@ -464,6 +467,7 @@ enum mac80211_tx_control_flags {
         IEEE80211_TX_STAT_AMPDU                 = BIT(10),
         IEEE80211_TX_STAT_AMPDU_NO_BACK         = BIT(11),
         IEEE80211_TX_CTL_RATE_CTRL_PROBE        = BIT(12),
+        IEEE80211_TX_INTFL_OFFCHAN_TX_OK        = BIT(13),
         IEEE80211_TX_INTFL_NEED_TXPROCESSING    = BIT(14),
         IEEE80211_TX_INTFL_RETRIED              = BIT(15),
         IEEE80211_TX_INTFL_DONT_ENCRYPT         = BIT(16),