mac80211: introduce flush operation

We've long lacked a good confirmation that frames
have really gone out, e.g. before going off-channel
for a scan. Add a flush() operation that drivers
can implement to provide that confirmation, and use
it in a few places:
 * before scanning sends the nullfunc frames
 * after scanning sends the nullfunc frames, if any
 * when going idle, to send any pending frames

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index ae1830056521..d98c45e5528b 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -418,9 +418,10 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local)
         local->next_scan_state = SCAN_DECISION;
         local->scan_channel_idx = 0;
 
+        drv_flush(local, false);
+
         ieee80211_configure_filter(local);
 
-        /* TODO: start scan as soon as all nullfunc frames are ACKed */
         ieee80211_queue_delayed_work(&local->hw,
                                      &local->scan_work,
                                      IEEE80211_CHANNEL_TIME);
@@ -584,8 +585,16 @@ static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *loca
 
         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 
+        /*
+         * What if the nullfunc frames didn't arrive?
+         */
+        drv_flush(local, false);
+        if (local->ops->flush)
+                *next_delay = 0;
+        else
+                *next_delay = HZ / 10;
+
         /* advance to the next channel to be scanned */
-        *next_delay = HZ / 10;
         local->next_scan_state = SCAN_SET_CHANNEL;
 }