mac80211: also expire filtered frames

mac80211 will expire normal PS-buffered frames, but
if the device rejected some frames for a sleeping
station, these won't be on the ps_tx_buf queue but
on the tx_filtered queue instead; this is done to
avoid reordering.

However, mac80211 will not expire frames from the
filtered queue, let's fix that.

Also add a more comments to what all this expiry is
doing and how it works.

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

1 files changed, 52 insertions, 5 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 863d59fe6886..8dabe66fc37f 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -709,6 +709,39 @@ static bool sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
         if (!sta->sdata->bss)
                 return false;
 
+        /*
+         * First check for frames that should expire on the filtered
+         * queue. Frames here were rejected by the driver and are on
+         * a separate queue to avoid reordering with normal PS-buffered
+         * frames. They also aren't accounted for right now in the
+         * total_ps_buffered counter.
+         */
+        for (;;) {
+                spin_lock_irqsave(&sta->tx_filtered.lock, flags);
+                skb = skb_peek(&sta->tx_filtered);
+                if (sta_info_buffer_expired(sta, skb))
+                        skb = __skb_dequeue(&sta->tx_filtered);
+                else
+                        skb = NULL;
+                spin_unlock_irqrestore(&sta->tx_filtered.lock, flags);
+
+                /*
+                 * Frames are queued in order, so if this one
+                 * hasn't expired yet we can stop testing. If
+                 * we actually reached the end of the queue we
+                 * also need to stop, of course.
+                 */
+                if (!skb)
+                        break;
+                dev_kfree_skb(skb);
+        }
+
+        /*
+         * Now also check the normal PS-buffered queue, this will
+         * only find something if the filtered queue was emptied
+         * since the filtered frames are all before the normal PS
+         * buffered frames.
+         */
         for (;;) {
                 spin_lock_irqsave(&sta->ps_tx_buf.lock, flags);
                 skb = skb_peek(&sta->ps_tx_buf);
@@ -718,6 +751,11 @@ static bool sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
                         skb = NULL;
                 spin_unlock_irqrestore(&sta->ps_tx_buf.lock, flags);
 
+                /*
+                 * frames are queued in order, so if this one
+                 * hasn't expired yet (or we reached the end of
+                 * the queue) we can stop testing
+                 */
                 if (!skb)
                         break;
 
@@ -727,13 +765,22 @@ static bool sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
                        sta->sta.addr);
 #endif
                 dev_kfree_skb(skb);
-
-                /* if the queue is now empty recalc TIM bit */
-                if (skb_queue_empty(&sta->ps_tx_buf))
-                        sta_info_recalc_tim(sta);
         }
 
-        return !skb_queue_empty(&sta->ps_tx_buf);
+        /*
+         * Finally, recalculate the TIM bit for this station -- it might
+         * now be clear because the station was too slow to retrieve its
+         * frames.
+         */
+        sta_info_recalc_tim(sta);
+
+        /*
+         * Return whether there are any frames still buffered, this is
+         * used to check whether the cleanup timer still needs to run,
+         * if there are no frames we don't need to rearm the timer.
+         */
+        return !(skb_queue_empty(&sta->ps_tx_buf) &&
+                 skb_queue_empty(&sta->tx_filtered));
 }
 
 static int __must_check __sta_info_destroy(struct sta_info *sta)