mac80211: Retry null data frame for power save

commit 375177bf35efc08e1bd37bbda4cc0c8cc4db8500 upstream.

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>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 35 insertions, 5 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 998c30fc898..c39ed079294 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -908,6 +908,9 @@ enum ieee80211_tkip_key_type {
  * @IEEE80211_HW_BEACON_FILTER:
  *	Hardware supports dropping of irrelevant beacon frames to
  *	avoid waking up cpu.
+ * @IEEE80211_HW_REPORTS_TX_ACK_STATUS:
+ *	Hardware can provide ack status reports of Tx frames to
+ *	the stack.
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_RX_INCLUDES_FCS			= 1<<1,
@@ -924,6 +927,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_SUPPORTS_DYNAMIC_PS		= 1<<12,
 	IEEE80211_HW_MFP_CAPABLE			= 1<<13,
 	IEEE80211_HW_BEACON_FILTER			= 1<<14,
+	IEEE80211_HW_REPORTS_TX_ACK_STATUS		= 1<<15,
 };
 
 /**
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 5a461641e94..ca62bfe229d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -264,6 +264,7 @@ enum ieee80211_sta_flags {
 	IEEE80211_STA_DISABLE_11N	= BIT(4),
 	IEEE80211_STA_CSA_RECEIVED	= BIT(5),
 	IEEE80211_STA_MFP_ENABLED	= BIT(6),
+	IEEE80211_STA_NULLFUNC_ACKED	= BIT(7),
 };
 
 /* flags for MLME request */
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 797f53942e5..19fbd25a705 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -441,6 +441,7 @@ 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;
 
 	sta = sta_info_get(local, hdr->addr1);
 
@@ -522,6 +523,20 @@ 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);
 
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 6cae2954963..4a15df1f964 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -650,8 +650,11 @@ 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);
+		}
 	}
 }
 
@@ -742,6 +745,7 @@ 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)
@@ -750,11 +754,16 @@ 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)
@@ -2458,6 +2467,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 	list_add(&wk->list, &ifmgd->work_list);
 
 	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 ||