mac80211: remove TX latency measurement code

Revert commit ad38bfc916da ("mac80211: Tx frame latency statistics")
(along with some follow-up fixes).

This code turned out not to be as useful in the current form as we
thought, and we've internally hacked it up more, but that's not
very suitable for upstream (for now), and we might just do that
with tracing instead.

Therefore, for now at least, remove this code. We might also need
to use the skb->tstamp field for the TCP performance issue, which
is more important than the debugging.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 0 insertions, 74 deletions

diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index e679b7c9b160..2c51742428d5 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -12,7 +12,6 @@
 
 #include <linux/export.h>
 #include <linux/etherdevice.h>
-#include <linux/time.h>
 #include <net/mac80211.h>
 #include <asm/unaligned.h>
 #include "ieee80211_i.h"
@@ -515,73 +514,6 @@ static void ieee80211_report_used_skb(struct ieee80211_local *local,
 }
 
 /*
- * Measure Tx frame completion and removal time for Tx latency statistics
- * calculation. A single Tx frame latency should be measured from when it
- * is entering the Kernel until we receive Tx complete confirmation indication
- * and remove the skb.
- */
-static void ieee80211_tx_latency_end_msrmnt(struct ieee80211_local *local,
-					    struct sk_buff *skb,
-					    struct sta_info *sta,
-					    struct ieee80211_hdr *hdr)
-{
-	u32 msrmnt;
-	u16 tid;
-	u8 *qc;
-	int i, bin_range_count;
-	u32 *bin_ranges;
-	__le16 fc;
-	struct ieee80211_tx_latency_stat *tx_lat;
-	struct ieee80211_tx_latency_bin_ranges *tx_latency;
-	ktime_t skb_arv = skb->tstamp;
-
-	tx_latency = rcu_dereference(local->tx_latency);
-
-	/* assert Tx latency stats are enabled & frame arrived when enabled */
-	if (!tx_latency || !ktime_to_ns(skb_arv))
-		return;
-
-	fc = hdr->frame_control;
-
-	if (!ieee80211_is_data(fc)) /* make sure it is a data frame */
-		return;
-
-	/* get frame tid */
-	if (ieee80211_is_data_qos(hdr->frame_control)) {
-		qc = ieee80211_get_qos_ctl(hdr);
-		tid = qc[0] & IEEE80211_QOS_CTL_TID_MASK;
-	} else {
-		tid = 0;
-	}
-
-	tx_lat = &sta->tx_lat[tid];
-
-	/* Calculate the latency */
-	msrmnt = ktime_to_ms(ktime_sub(ktime_get(), skb_arv));
-
-	if (tx_lat->max < msrmnt) /* update stats */
-		tx_lat->max = msrmnt;
-	tx_lat->counter++;
-	tx_lat->sum += msrmnt;
-
-	if (!tx_lat->bins) /* bins not activated */
-		return;
-
-	/* count how many Tx frames transmitted with the appropriate latency */
-	bin_range_count = tx_latency->n_ranges;
-	bin_ranges = tx_latency->ranges;
-
-	for (i = 0; i < bin_range_count; i++) {
-		if (msrmnt <= bin_ranges[i]) {
-			tx_lat->bins[i]++;
-			break;
-		}
-	}
-	if (i == bin_range_count) /* msrmnt is bigger than the biggest range */
-		tx_lat->bins[i]++;
-}
-
-/*
  * Use a static threshold for now, best value to be determined
  * by testing ...
  * Should it depend on:
@@ -853,12 +785,6 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 
 		if (acked)
 			sta->last_ack_signal = info->status.ack_signal;
-
-		/*
-		 * Measure frame removal for tx latency
-		 * statistics calculation
-		 */
-		ieee80211_tx_latency_end_msrmnt(local, skb, sta, hdr);
 	}
 
 	rcu_read_unlock();