[PATCH 3/3] ifb: move tq from ifb_private

[Changli Gao <xiaosuo@gmail.com>]

tq is only used in ri_tasklet, so we move it from ifb_private to a
stack variable of ri_tasklet.

skb_queue_splice_tail_init() is used instead of the open coded and slow
one.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
---
 drivers/net/ifb.c |   49 ++++++++++++-------------------------------------
 1 file changed, 12 insertions(+), 37 deletions(-)
diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
index d1e362a..cd6e90d 100644
--- a/drivers/net/ifb.c
+++ b/drivers/net/ifb.c
@@ -39,9 +39,7 @@
 #define TX_Q_LIMIT    32
 struct ifb_private {
 	struct tasklet_struct   ifb_tasklet;
-	int     tasklet_pending;
 	struct sk_buff_head     rq;
-	struct sk_buff_head     tq;
 };
 
 static int numifbs = 2;
@@ -53,27 +51,25 @@ static int ifb_close(struct net_device *dev);
 
 static void ri_tasklet(unsigned long dev)
 {
-
 	struct net_device *_dev = (struct net_device *)dev;
 	struct ifb_private *dp = netdev_priv(_dev);
 	struct net_device_stats *stats = &_dev->stats;
 	struct netdev_queue *txq;
 	struct sk_buff *skb;
+	struct sk_buff_head tq;
 
+	__skb_queue_head_init(&tq);
 	txq = netdev_get_tx_queue(_dev, 0);
-	if ((skb = skb_peek(&dp->tq)) == NULL) {
-		if (__netif_tx_trylock(txq)) {
-			while ((skb = skb_dequeue(&dp->rq)) != NULL) {
-				skb_queue_tail(&dp->tq, skb);
-			}
-			__netif_tx_unlock(txq);
-		} else {
-			/* reschedule */
-			goto resched;
-		}
+	if (!__netif_tx_trylock(txq)) {
+		tasklet_schedule(&dp->ifb_tasklet);
+		return;
 	}
+	skb_queue_splice_tail_init(&dp->rq, &tq);
+	if (netif_tx_queue_stopped(txq))
+		netif_tx_wake_queue(txq);
+	__netif_tx_unlock(txq);
 
-	while ((skb = skb_dequeue(&dp->tq)) != NULL) {
+	while ((skb = __skb_dequeue(&tq)) != NULL) {
 		u32 from = G_TC_FROM(skb->tc_verd);
 
 		skb->tc_verd = 0;
@@ -87,7 +83,7 @@ static void ri_tasklet(unsigned long dev)
 			rcu_read_unlock();
 			dev_kfree_skb(skb);
 			stats->tx_dropped++;
-			break;
+			continue;
 		}
 		rcu_read_unlock();
 		skb->skb_iif = _dev->ifindex;
@@ -100,23 +96,6 @@ static void ri_tasklet(unsigned long dev)
 		} else
 			BUG();
 	}
-
-	if (__netif_tx_trylock(txq)) {
-		if ((skb = skb_peek(&dp->rq)) == NULL) {
-			dp->tasklet_pending = 0;
-			if (netif_queue_stopped(_dev))
-				netif_wake_queue(_dev);
-		} else {
-			__netif_tx_unlock(txq);
-			goto resched;
-		}
-		__netif_tx_unlock(txq);
-	} else {
-resched:
-		dp->tasklet_pending = 1;
-		tasklet_schedule(&dp->ifb_tasklet);
-	}
-
 }
 
 static const struct net_device_ops ifb_netdev_ops = {
@@ -162,10 +141,8 @@ static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	skb_queue_tail(&dp->rq, skb);
-	if (!dp->tasklet_pending) {
-		dp->tasklet_pending = 1;
+	if (skb_queue_len(&dp->rq) == 1)
 		tasklet_schedule(&dp->ifb_tasklet);
-	}
 
 	return NETDEV_TX_OK;
 }
@@ -177,7 +154,6 @@ static int ifb_close(struct net_device *dev)
 	tasklet_kill(&dp->ifb_tasklet);
 	netif_stop_queue(dev);
 	skb_queue_purge(&dp->rq);
-	skb_queue_purge(&dp->tq);
 	return 0;
 }
 
@@ -187,7 +163,6 @@ static int ifb_open(struct net_device *dev)
 
 	tasklet_init(&dp->ifb_tasklet, ri_tasklet, (unsigned long)dev);
 	skb_queue_head_init(&dp->rq);
-	skb_queue_head_init(&dp->tq);
 	netif_start_queue(dev);
 
 	return 0;