mac80211: reply only once to each PS-poll

If a PS-poll frame is retried (but was received)
there is no way to detect that since it has no
sequence number. As a consequence, the standard
asks us to not react to PS-poll frames until the
response to one made it out (was ACKed or lost).

Implement this by using the WLAN_STA_SP flags to
also indicate a PS-Poll "service period" and the
IEEE80211_TX_STATUS_EOSP flag for the response
packet to indicate the end of the "SP" as usual.

We could use separate flags, but that will most
likely completely confuse drivers, and while the
standard doesn't exclude simultaneously polling
using uAPSD and PS-Poll, doing that seems quite
problematic.

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

1 files changed, 6 insertions, 4 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 9a703f00b5fb..32c8ee43f720 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1194,10 +1194,12 @@ ieee80211_rx_h_uapsd_and_pspoll(struct ieee80211_rx_data *rx)
                 return RX_CONTINUE;
 
         if (unlikely(ieee80211_is_pspoll(hdr->frame_control))) {
-                if (!test_sta_flags(rx->sta, WLAN_STA_PS_DRIVER))
-                        ieee80211_sta_ps_deliver_poll_response(rx->sta);
-                else
-                        set_sta_flags(rx->sta, WLAN_STA_PSPOLL);
+                if (!test_sta_flags(rx->sta, WLAN_STA_SP)) {
+                        if (!test_sta_flags(rx->sta, WLAN_STA_PS_DRIVER))
+                                ieee80211_sta_ps_deliver_poll_response(rx->sta);
+                        else
+                                set_sta_flags(rx->sta, WLAN_STA_PSPOLL);
+                }
 
                 /* Free PS Poll skb here instead of returning RX_DROP that would
                  * count as an dropped frame. */