mac80211: fix CSA tx queue stopping

It was possible for tx queues to be stuck stopped
if AP CSA finalization failed. In that case
neither stop_ap nor do_stop woke the queues up.
This means it was impossible to perform tx at all
until driver was reloaded or a successful CSA was
performed later.

It was possible to solve this in a simpler manner
however this is more robust and future proof
(having multi-vif CSA in mind).

New sdata->csa_block_tx is introduced to keep
track of which interfaces requested tx to be
blocked for CSA. This is required because mac80211
stops all tx queues for that purpose. This means
queues must be awoken only when last tx-blocking
CSA interface is finished.

It is still possible to have tx queues stopped
after CSA failure but as soon as offending
interfaces are stopped from userspace (stop_ap or
ifdown) tx queues are woken up properly.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index bdb4a7cbab31..3541c48a97cd 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1113,7 +1113,9 @@ enum ieee80211_vif_flags {
  * @addr: address of this interface
  * @p2p: indicates whether this AP or STA interface is a p2p
  *      interface, i.e. a GO or p2p-sta respectively
- * @csa_active: marks whether a channel switch is going on
+ * @csa_active: marks whether a channel switch is going on. Internally it is
+ *      write-protected by sdata_lock and local->mtx so holding either is fine
+ *      for read access.
  * @driver_flags: flags/capabilities the driver has for this interface,
  *      these need to be set (or cleared) when the interface is added
  *      or, if supported by the driver, the interface type is changed