mac80211: Retry null data frame for power save.

Even if the null data frame is not acked by the AP, mac80211
goes into power save. This might lead to loss of frames
from the AP.
Prevent this by restarting dynamic_ps_timer when ack is not
received for null data frames.

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

4 files changed, 37 insertions, 7 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 414d774028ba..314e98173166 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -945,6 +945,11 @@ enum ieee80211_tkip_key_type {
  *      Hardware supports Unscheduled Automatic Power Save Delivery
  *      (U-APSD) in managed mode. The mode is configured with
  *      conf_tx() operation.
+ *
+ * @IEEE80211_HW_REPORTS_TX_ACK_STATUS:
+ *      Hardware can provide ack status reports of Tx frames to
+ *      the stack.
+ *
  */
 enum ieee80211_hw_flags {
         IEEE80211_HW_HAS_RATE_CONTROL                   = 1<<0,
@@ -965,6 +970,7 @@ enum ieee80211_hw_flags {
         IEEE80211_HW_SUPPORTS_STATIC_SMPS               = 1<<15,
         IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS              = 1<<16,
         IEEE80211_HW_SUPPORTS_UAPSD                     = 1<<17,
+        IEEE80211_HW_REPORTS_TX_ACK_STATUS              = 1<<18,
 };
 
 /**
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a5911191f224..9dd98b674cbc 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -316,6 +316,7 @@ enum ieee80211_sta_flags {
         IEEE80211_STA_CSA_RECEIVED      = BIT(5),
         IEEE80211_STA_MFP_ENABLED       = BIT(6),
         IEEE80211_STA_UAPSD_ENABLED     = BIT(7),
+        IEEE80211_STA_NULLFUNC_ACKED    = BIT(8),
 };
 
 struct ieee80211_if_managed {
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 7a7921476582..ee9443dc20ff 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -434,8 +434,11 @@ static void ieee80211_enable_ps(struct ieee80211_local *local,
         } else {
                 if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
                         ieee80211_send_nullfunc(local, sdata, 1);
-                conf->flags |= IEEE80211_CONF_PS;
-                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+
+                if (!(local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS)) {
+                        conf->flags |= IEEE80211_CONF_PS;
+                        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+                }
         }
 }
 
@@ -541,6 +544,7 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
                 container_of(work, struct ieee80211_local,
                              dynamic_ps_enable_work);
         struct ieee80211_sub_if_data *sdata = local->ps_sdata;
+        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 
         /* can only happen when PS was just disabled anyway */
         if (!sdata)
@@ -549,11 +553,16 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
         if (local->hw.conf.flags & IEEE80211_CONF_PS)
                 return;
 
-        if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
+        if ((local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK) &&
+            (!(ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)))
                 ieee80211_send_nullfunc(local, sdata, 1);
 
-        local->hw.conf.flags |= IEEE80211_CONF_PS;
-        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+        if (!(local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) ||
+            (ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
+                ifmgd->flags &= ~IEEE80211_STA_NULLFUNC_ACKED;
+                local->hw.conf.flags |= IEEE80211_CONF_PS;
+                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+        }
 }
 
 void ieee80211_dynamic_ps_timer(unsigned long data)
@@ -1892,6 +1901,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
                 return -ENOMEM;
 
         ifmgd->flags &= ~IEEE80211_STA_DISABLE_11N;
+        ifmgd->flags &= ~IEEE80211_STA_NULLFUNC_ACKED;
 
         for (i = 0; i < req->crypto.n_ciphers_pairwise; i++)
                 if (req->crypto.ciphers_pairwise[i] == WLAN_CIPHER_SUITE_WEP40 ||
diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index e57ad6b1d7ea..ded98730c111 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -188,6 +188,7 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
         rcu_read_lock();
 
         sband = local->hw.wiphy->bands[info->band];
+        fc = hdr->frame_control;
 
         for_each_sta_info(local, hdr->addr1, sta, tmp) {
                 /* skip wrong virtual interface */
@@ -205,8 +206,6 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
                         return;
                 }
 
-                fc = hdr->frame_control;
-
                 if ((info->flags & IEEE80211_TX_STAT_AMPDU_NO_BACK) &&
                     (ieee80211_is_data_qos(fc))) {
                         u16 tid, ssn;
@@ -275,6 +274,20 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
                         local->dot11FailedCount++;
         }
 
+        if (ieee80211_is_nullfunc(fc) && ieee80211_has_pm(fc) &&
+            (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) &&
+            !(info->flags & IEEE80211_TX_CTL_INJECTED) &&
+            local->ps_sdata && !(local->scanning)) {
+                if (info->flags & IEEE80211_TX_STAT_ACK) {
+                        local->ps_sdata->u.mgd.flags |=
+                                        IEEE80211_STA_NULLFUNC_ACKED;
+                        ieee80211_queue_work(&local->hw,
+                                        &local->dynamic_ps_enable_work);
+                } else
+                        mod_timer(&local->dynamic_ps_timer, jiffies +
+                                        msecs_to_jiffies(10));
+        }
+
         /* this was a transmitted frame, but now we want to reuse it */
         skb_orphan(skb);