mac80211_hwsim: fix beacon timestamp and mactime

Set the beacon timestamp once during "transmission" so the
monitor interface also gets a timestamped beacon.

Also use a common base between TX timestamp and RX
mactime. This eliminates "TX" path delay, which shows up
as a constant error in Toffset.

Get the global TSF once before iterating over all RX HWs,
so they all set a mactime with the same time base.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 39 insertions, 18 deletions

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index b6e2caa024a7..b73e497fe770 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -363,6 +363,8 @@ struct mac80211_hwsim_data {
         /* difference between this hw's clock and the real clock, in usecs */
         s64 tsf_offset;
         s64 bcn_delta;
+        /* absolute beacon transmission time. Used to cover up "tx" delay. */
+        u64 abs_bcn_ts;
 };
 
 
@@ -410,15 +412,19 @@ static netdev_tx_t hwsim_mon_xmit(struct sk_buff *skb,
         return NETDEV_TX_OK;
 }
 
+static inline u64 mac80211_hwsim_get_tsf_raw(void)
+{
+        return ktime_to_us(ktime_get_real());
+}
+
 static __le64 __mac80211_hwsim_get_tsf(struct mac80211_hwsim_data *data)
 {
-        struct timeval tv = ktime_to_timeval(ktime_get_real());
-        u64 now = tv.tv_sec * USEC_PER_SEC + tv.tv_usec;
+        u64 now = mac80211_hwsim_get_tsf_raw();
         return cpu_to_le64(now + data->tsf_offset);
 }
 
 static u64 mac80211_hwsim_get_tsf(struct ieee80211_hw *hw,
-                struct ieee80211_vif *vif)
+                                  struct ieee80211_vif *vif)
 {
         struct mac80211_hwsim_data *data = hw->priv;
         return le64_to_cpu(__mac80211_hwsim_get_tsf(data));
@@ -705,7 +711,7 @@ static bool mac80211_hwsim_tx_frame_no_nl(struct ieee80211_hw *hw,
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
         struct ieee80211_rx_status rx_status;
-        struct ieee80211_rate *txrate = ieee80211_get_tx_rate(hw, info);
+        u64 now;
 
         memset(&rx_status, 0, sizeof(rx_status));
         rx_status.flag |= RX_FLAG_MACTIME_START;
@@ -731,11 +737,23 @@ static bool mac80211_hwsim_tx_frame_no_nl(struct ieee80211_hw *hw,
         secpath_reset(skb);
         nf_reset(skb);
 
+        /*
+         * Get absolute mactime here so all HWs RX at the "same time", and
+         * absolute TX time for beacon mactime so the timestamp matches.
+         * Giving beacons a different mactime than non-beacons looks messy, but
+         * it helps the Toffset be exact and a ~10us mactime discrepancy
+         * probably doesn't really matter.
+         */
+        if (ieee80211_is_beacon(hdr->frame_control) ||
+            ieee80211_is_probe_resp(hdr->frame_control))
+                now = data->abs_bcn_ts;
+        else
+                now = mac80211_hwsim_get_tsf_raw();
+
         /* Copy skb to all enabled radios that are on the current frequency */
         spin_lock(&hwsim_radio_lock);
         list_for_each_entry(data2, &hwsim_radios, list) {
                 struct sk_buff *nskb;
-                struct ieee80211_mgmt *mgmt;
                 struct tx_iter_data tx_iter_data = {
                         .receive = false,
                         .channel = chan,
@@ -787,17 +805,7 @@ static bool mac80211_hwsim_tx_frame_no_nl(struct ieee80211_hw *hw,
                 if (mac80211_hwsim_addr_match(data2, hdr->addr1))
                         ack = true;
 
-                /* set bcn timestamp relative to receiver mactime */
-                rx_status.mactime =
-                                le64_to_cpu(__mac80211_hwsim_get_tsf(data2));
-                mgmt = (struct ieee80211_mgmt *) nskb->data;
-                if (ieee80211_is_beacon(mgmt->frame_control) ||
-                    ieee80211_is_probe_resp(mgmt->frame_control))
-                        mgmt->u.beacon.timestamp = cpu_to_le64(
-                                rx_status.mactime +
-                                (data->tsf_offset - data2->tsf_offset) +
-                                24 * 8 * 10 / txrate->bitrate);
-
+                rx_status.mactime = now + data2->tsf_offset;
 #if 0
                 /*
                  * Don't enable this code by default as the OUI 00:00:00
@@ -987,7 +995,11 @@ static void mac80211_hwsim_tx_frame(struct ieee80211_hw *hw,
 static void mac80211_hwsim_beacon_tx(void *arg, u8 *mac,
                                      struct ieee80211_vif *vif)
 {
-        struct ieee80211_hw *hw = arg;
+        struct mac80211_hwsim_data *data = arg;
+        struct ieee80211_hw *hw = data->hw;
+        struct ieee80211_tx_info *info;
+        struct ieee80211_rate *txrate;
+        struct ieee80211_mgmt *mgmt;
         struct sk_buff *skb;
 
         hwsim_check_magic(vif);
@@ -1000,6 +1012,15 @@ static void mac80211_hwsim_beacon_tx(void *arg, u8 *mac,
         skb = ieee80211_beacon_get(hw, vif);
         if (skb == NULL)
                 return;
+        info = IEEE80211_SKB_CB(skb);
+        txrate = ieee80211_get_tx_rate(hw, info);
+
+        mgmt = (struct ieee80211_mgmt *) skb->data;
+        /* fake header transmission time */
+        data->abs_bcn_ts = mac80211_hwsim_get_tsf_raw();
+        mgmt->u.beacon.timestamp = cpu_to_le64(data->abs_bcn_ts +
+                                               data->tsf_offset +
+                                               24 * 8 * 10 / txrate->bitrate);
 
         mac80211_hwsim_tx_frame(hw, skb,
                                 rcu_dereference(vif->chanctx_conf)->def.chan);
@@ -1020,7 +1041,7 @@ mac80211_hwsim_beacon(struct hrtimer *timer)
 
         ieee80211_iterate_active_interfaces_atomic(
                 hw, IEEE80211_IFACE_ITER_NORMAL,
-                mac80211_hwsim_beacon_tx, hw);
+                mac80211_hwsim_beacon_tx, data);
 
         /* beacon at new TBTT + beacon interval */
         if (data->bcn_delta) {