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, 22 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 0e56ac5729ef..a23a84e93e80 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -20,7 +20,6 @@
 #include <linux/bitmap.h>
 #include <linux/rcupdate.h>
 #include <linux/export.h>
-#include <linux/time.h>
 #include <net/net_namespace.h>
 #include <net/ieee80211_radiotap.h>
 #include <net/cfg80211.h>
@@ -1787,23 +1786,6 @@ fail:
 	return NETDEV_TX_OK; /* meaning, we dealt with the skb */
 }
 
-/*
- * Measure Tx frame arrival 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 the skb is
- * freed.
- */
-static void ieee80211_tx_latency_start_msrmnt(struct ieee80211_local *local,
-					      struct sk_buff *skb)
-{
-	struct ieee80211_tx_latency_bin_ranges *tx_latency;
-
-	tx_latency = rcu_dereference(local->tx_latency);
-	if (!tx_latency)
-		return;
-	skb->tstamp = ktime_get();
-}
-
 /**
  * ieee80211_build_hdr - build 802.11 header in the given frame
  * @sdata: virtual interface to build the header for
@@ -2259,7 +2241,6 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 				  u32 info_flags)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
-	struct ieee80211_local *local = sdata->local;
 
 	if (unlikely(skb->len < ETH_HLEN)) {
 		kfree_skb(skb);
@@ -2268,9 +2249,6 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 
 	rcu_read_lock();
 
-	/* Measure frame arrival for Tx latency statistics calculation */
-	ieee80211_tx_latency_start_msrmnt(local, skb);
-
 	skb = ieee80211_build_hdr(sdata, skb, info_flags);
 	if (IS_ERR(skb))
 		goto out;