mac80211: fix offloaded BA session traffic after hw restart

When starting an offloaded BA session it is
unknown what starting sequence number should be
used. Using last_seq worked in most cases except
after hw restart.

When hw restart is requested last_seq is
(rightfully so) kept unmodified. This ended up
with BA sessions being restarted with an aribtrary
BA window values resulting in dropped frames until
sequence numbers caught up.

Instead of last_seq pick seqno of a first Rxed
frame of a given BA session.

This fixes stalled traffic after hw restart with
offloaded BA sessions (currently only ath10k).

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 89c40d5..16dc1d4 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -167,6 +167,8 @@
  * @dialog_token: dialog token for aggregation session
  * @rcu_head: RCU head used for freeing this struct
  * @reorder_lock: serializes access to reorder buffer, see below.
+ * @auto_seq: used for offloaded BA sessions to automatically pick head_seq_and
+ *	and ssn.
  *
  * This structure's lifetime is managed by RCU, assignments to
  * the array holding it must hold the aggregation mutex.
@@ -190,6 +192,7 @@
 	u16 buf_size;
 	u16 timeout;
 	u8 dialog_token;
+	bool auto_seq;
 };
 
 /**