net: trans_start cleanups

Now that core network takes care of trans_start updates, dont do it
in drivers themselves, if possible. Drivers can avoid one cache miss
(on dev->trans_start) in their start_xmit() handler.

Exceptions are NETIF_F_LLTX drivers

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tokenring/ibmtr.c b/drivers/net/tokenring/ibmtr.c
index eebdaae..91e6c78 100644
--- a/drivers/net/tokenring/ibmtr.c
+++ b/drivers/net/tokenring/ibmtr.c
@@ -1041,7 +1041,6 @@
 	writew(ti->exsap_station_id, ti->srb + STATION_ID_OFST);
 	writeb(CMD_IN_SRB, ti->mmio + ACA_OFFSET + ACA_SET + ISRA_ODD);
 	spin_unlock_irqrestore(&(ti->lock), flags);
-	dev->trans_start = jiffies;
 	return NETDEV_TX_OK;
 }
 
diff --git a/drivers/net/tokenring/smctr.c b/drivers/net/tokenring/smctr.c
index e405601..213b9af 100644
--- a/drivers/net/tokenring/smctr.c
+++ b/drivers/net/tokenring/smctr.c
@@ -4562,7 +4562,7 @@
          * fake transmission time and go on trying. Our own timeout
          * routine is in sktr_timer_chk()
          */
-        dev->trans_start = jiffies;
+        dev->trans_start = jiffies; /* prevent tx timeout */
         netif_wake_queue(dev);
 }
 
diff --git a/drivers/net/tokenring/tms380tr.c b/drivers/net/tokenring/tms380tr.c
index c169fd0..8cb126a 100644
--- a/drivers/net/tokenring/tms380tr.c
+++ b/drivers/net/tokenring/tms380tr.c
@@ -592,7 +592,7 @@
 	 * fake transmission time and go on trying. Our own timeout
 	 * routine is in tms380tr_timer_chk()
 	 */
-	dev->trans_start = jiffies;
+	dev->trans_start = jiffies; /* prevent tx timeout */
 	netif_wake_queue(dev);
 }