net: txq_trans_update() helper

We would like to get rid of netdev->trans_start = jiffies; that about all net
drivers have to use in their start_xmit() function, and use txq->trans_start
instead.

This can be done generically in core network, as suggested by David.

Some devices, (particularly loopback) dont need trans_start update, because
they dont have transmit watchdog. We could add a new device flag, or rely
on fact that txq->tran_start can be updated is txq->xmit_lock_owner is
different than -1. Use a helper function to hide our choice.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 15 insertions, 1 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ae3c2099a04b..586b71f0358c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1674,6 +1674,12 @@ static inline void __netif_tx_unlock_bh(struct netdev_queue *txq)
         spin_unlock_bh(&txq->_xmit_lock);
 }
 
+static inline void txq_trans_update(struct netdev_queue *txq)
+{
+        if (txq->xmit_lock_owner != -1)
+                txq->trans_start = jiffies;
+}
+
 /**
  *      netif_tx_lock - grab network device transmit lock
  *      @dev: network device
diff --git a/net/core/dev.c b/net/core/dev.c
index 241613f6dd2f..5eb3e48ab31d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1698,6 +1698,8 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
                         skb->dst = NULL;
                 }
                 rc = ops->ndo_start_xmit(skb, dev);
+                if (rc == 0)
+                        txq_trans_update(txq);
                 /*
                  * TODO: if skb_orphan() was called by
                  * dev->hard_start_xmit() (for example, the unmodified
@@ -1727,6 +1729,7 @@ gso:
                         skb->next = nskb;
                         return rc;
                 }
+                txq_trans_update(txq);
                 if (unlikely(netif_tx_queue_stopped(txq) && skb->next))
                         return NETDEV_TX_BUSY;
         } while (skb->next);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 67b4f3e3d4a5..7ab31a7576a1 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -302,8 +302,11 @@ static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
                      tries > 0; --tries) {
                         if (__netif_tx_trylock(txq)) {
-                                if (!netif_tx_queue_stopped(txq))
+                                if (!netif_tx_queue_stopped(txq)) {
                                         status = ops->ndo_start_xmit(skb, dev);
+                                        if (status == NETDEV_TX_OK)
+                                                txq_trans_update(txq);
+                                }
                                 __netif_tx_unlock(txq);
 
                                 if (status == NETDEV_TX_OK)
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 0666a827bc62..b8ccd3c88d63 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3438,6 +3438,7 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
               retry_now:
                 ret = (*xmit)(pkt_dev->skb, odev);
                 if (likely(ret == NETDEV_TX_OK)) {
+                        txq_trans_update(txq);
                         pkt_dev->last_ok = 1;
                         pkt_dev->sofar++;
                         pkt_dev->seq_num++;
diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index 428a5ef5b944..a886496bdc3a 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -308,6 +308,7 @@ restart:
                                 if (!netif_tx_queue_stopped(slave_txq) &&
                                     !netif_tx_queue_frozen(slave_txq) &&
                                     slave_ops->ndo_start_xmit(skb, slave) == 0) {
+                                        txq_trans_update(slave_txq);
                                         __netif_tx_unlock(slave_txq);
                                         master->slaves = NEXT_SLAVE(q);
                                         netif_wake_queue(dev);