[PATCH 0/2] station packet loss notification

[PATCH 0/2] station packet loss notification

[Johannes Berg]

This is a repost of my earlier RFC series,
with the additional fix of not sending an
event for every frame after the threshold
is reached.

johannes

[PATCH 1/2] cfg80211: allow using CQM event to notify packet loss

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

This adds the ability for drivers to use CQM events
to notify about packet loss for specific stations
(which could be the AP for the managed mode case).
Since the threshold might be determined by the
driver (it isn't passed in right now) it will be
passed out of the driver to userspace in the event.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 include/linux/nl80211.h |    3 +++
 include/net/cfg80211.h  |   12 ++++++++++++
 net/wireless/mlme.c     |   12 ++++++++++++
 net/wireless/nl80211.c  |   45 +++++++++++++++++++++++++++++++++++++++++++++
 net/wireless/nl80211.h  |    4 ++++
 5 files changed, 76 insertions(+)

--- wireless-testing.orig/include/linux/nl80211.h	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/include/linux/nl80211.h	2010-11-24 08:09:22.000000000 +0100
@@ -1821,6 +1821,8 @@ enum nl80211_ps_state {
  *	the minimum amount the RSSI level must change after an event before a
  *	new event may be issued (to reduce effects of RSSI oscillation).
  * @NL80211_ATTR_CQM_RSSI_THRESHOLD_EVENT: RSSI threshold event
+ * @NL80211_ATTR_CQM_PKT_LOSS_EVENT: a u32 value indicating that this many
+ *	consecutive packets were not acknowledged by the peer
  * @__NL80211_ATTR_CQM_AFTER_LAST: internal
  * @NL80211_ATTR_CQM_MAX: highest key attribute
  */
@@ -1829,6 +1831,7 @@ enum nl80211_attr_cqm {
 	NL80211_ATTR_CQM_RSSI_THOLD,
 	NL80211_ATTR_CQM_RSSI_HYST,
 	NL80211_ATTR_CQM_RSSI_THRESHOLD_EVENT,
+	NL80211_ATTR_CQM_PKT_LOSS_EVENT,
 
 	/* keep last */
 	__NL80211_ATTR_CQM_AFTER_LAST,
--- wireless-testing.orig/net/wireless/mlme.c	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/net/wireless/mlme.c	2010-11-24 08:09:22.000000000 +0100
@@ -1028,3 +1028,15 @@ void cfg80211_cqm_rssi_notify(struct net
 	nl80211_send_cqm_rssi_notify(rdev, dev, rssi_event, gfp);
 }
 EXPORT_SYMBOL(cfg80211_cqm_rssi_notify);
+
+void cfg80211_cqm_pktloss_notify(struct net_device *dev,
+				 const u8 *peer, u32 num_packets, gfp_t gfp)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct wiphy *wiphy = wdev->wiphy;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+
+	/* Indicate roaming trigger event to user space */
+	nl80211_send_cqm_pktloss_notify(rdev, dev, peer, num_packets, gfp);
+}
+EXPORT_SYMBOL(cfg80211_cqm_pktloss_notify);
--- wireless-testing.orig/net/wireless/nl80211.c	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/net/wireless/nl80211.c	2010-11-24 08:09:22.000000000 +0100
@@ -5688,6 +5688,51 @@ nl80211_send_cqm_rssi_notify(struct cfg8
 	nlmsg_free(msg);
 }
 
+void
+nl80211_send_cqm_pktloss_notify(struct cfg80211_registered_device *rdev,
+				struct net_device *netdev, const u8 *peer,
+				u32 num_packets, gfp_t gfp)
+{
+	struct sk_buff *msg;
+	struct nlattr *pinfoattr;
+	void *hdr;
+
+	msg = nlmsg_new(NLMSG_GOODSIZE, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_NOTIFY_CQM);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx);
+	NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, netdev->ifindex);
+	NLA_PUT(msg, NL80211_ATTR_MAC, ETH_ALEN, peer);
+
+	pinfoattr = nla_nest_start(msg, NL80211_ATTR_CQM);
+	if (!pinfoattr)
+		goto nla_put_failure;
+
+	NLA_PUT_U32(msg, NL80211_ATTR_CQM_PKT_LOSS_EVENT, num_packets);
+
+	nla_nest_end(msg, pinfoattr);
+
+	if (genlmsg_end(msg, hdr) < 0) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	genlmsg_multicast_netns(wiphy_net(&rdev->wiphy), msg, 0,
+				nl80211_mlme_mcgrp.id, gfp);
+	return;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	nlmsg_free(msg);
+}
+
 static int nl80211_netlink_notify(struct notifier_block * nb,
 				  unsigned long state,
 				  void *_notify)
--- wireless-testing.orig/net/wireless/nl80211.h	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/net/wireless/nl80211.h	2010-11-24 08:09:22.000000000 +0100
@@ -87,5 +87,9 @@ nl80211_send_cqm_rssi_notify(struct cfg8
 			     struct net_device *netdev,
 			     enum nl80211_cqm_rssi_threshold_event rssi_event,
 			     gfp_t gfp);
+void
+nl80211_send_cqm_pktloss_notify(struct cfg80211_registered_device *rdev,
+				struct net_device *netdev, const u8 *peer,
+				u32 num_packets, gfp_t gfp);
 
 #endif /* __NET_WIRELESS_NL80211_H */
--- wireless-testing.orig/include/net/cfg80211.h	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/include/net/cfg80211.h	2010-11-24 08:09:22.000000000 +0100
@@ -2605,6 +2605,18 @@ void cfg80211_cqm_rssi_notify(struct net
 			      enum nl80211_cqm_rssi_threshold_event rssi_event,
 			      gfp_t gfp);
 
+/**
+ * cfg80211_cqm_pktloss_notify - notify userspace about packetloss to peer
+ * @dev: network device
+ * @peer: peer's MAC address
+ * @num_packets: how many packets were lost -- should be a fixed threshold
+ *	but probably no less than maybe 50, or maybe a throughput dependent
+ *	threshold (to account for temporary interference)
+ * @gfp: context flags
+ */
+void cfg80211_cqm_pktloss_notify(struct net_device *dev,
+				 const u8 *peer, u32 num_packets, gfp_t gfp);
+
 /* Logging, debugging and troubleshooting/diagnostic helpers. */
 
 /* wiphy_printk helpers, similar to dev_printk */

[PATCH 2/2] mac80211: implement packet loss notification

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

For drivers that have accurate TX status reporting
we can report the number of consecutive lost packets
to userspace using the new cfg80211 CQM event. The
threshold is fixed right now, this may need to be
improved in the future.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
v2: don't send event on every packet

 net/mac80211/sta_info.h |    3 +++
 net/mac80211/status.c   |   22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+)

--- wireless-testing.orig/net/mac80211/sta_info.h	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/net/mac80211/sta_info.h	2010-11-24 08:09:23.000000000 +0100
@@ -250,6 +250,7 @@ enum plink_state {
  * @sta: station information we share with the driver
  * @dead: set to true when sta is unlinked
  * @uploaded: set to true when sta is uploaded to the driver
+ * @lost_packets: number of consecutive lost packets
  */
 struct sta_info {
 	/* General information, mostly static */
@@ -338,6 +339,8 @@ struct sta_info {
 	} debugfs;
 #endif
 
+	unsigned int lost_packets;
+
 	/* keep last! */
 	struct ieee80211_sta sta;
 };
--- wireless-testing.orig/net/mac80211/status.c	2010-11-23 10:36:12.000000000 +0100
+++ wireless-testing/net/mac80211/status.c	2010-11-24 08:09:23.000000000 +0100
@@ -157,6 +157,15 @@ static void ieee80211_frame_acked(struct
 	}
 }
 
+/*
+ * Use a static threshold for now, best value to be determined
+ * by testing ...
+ * Should it depend on:
+ *  - on # of retransmissions
+ *  - current throughput (higher value for higher tpt)?
+ */
+#define STA_LOST_PKT_THRESHOLD	50
+
 void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 {
 	struct sk_buff *skb2;
@@ -243,6 +252,19 @@ void ieee80211_tx_status(struct ieee8021
 		if (!(info->flags & IEEE80211_TX_CTL_INJECTED) &&
 		    (info->flags & IEEE80211_TX_STAT_ACK))
 			ieee80211_frame_acked(sta, skb);
+
+		if (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) {
+			if (info->flags & IEEE80211_TX_STAT_ACK) {
+				if (sta->lost_packets)
+					sta->lost_packets = 0;
+			} else if (++sta->lost_packets >= STA_LOST_PKT_THRESHOLD) {
+				cfg80211_cqm_pktloss_notify(sta->sdata->dev,
+							    sta->sta.addr,
+							    sta->lost_packets,
+							    GFP_ATOMIC);
+				sta->lost_packets = 0;
+			}
+		}
 	}
 
 	rcu_read_unlock();