net-xmit-lock-owner-cleanup.patch

From 356d32bec945c68aa111fa01ef40b098de658a05 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:30:11 -0500
Subject: [PATCH] net: xmit lock owner cleanup

commit 543a589a00e831de55e5f67802b73033dc2dd964 in tip.

- __netif_tx_lock() always passes in 'current' as the lock owner,
  so eliminate this parameter.

- likewise for HARD_TX_LOCK()

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
index ef2b781..d0bf40d 100644
--- a/drivers/net/bnx2.c
+++ b/drivers/net/bnx2.c
@@ -2863,7 +2863,7 @@ bnx2_tx_int(struct bnx2 *bp, struct bnx2_napi *bnapi, int budget)
 
 	if (unlikely(netif_tx_queue_stopped(txq)) &&
 		     (bnx2_tx_avail(bp, txr) > bp->tx_wake_thresh)) {
-		__netif_tx_lock(txq, (void *)current);
+		__netif_tx_lock(txq);
 		if ((netif_tx_queue_stopped(txq)) &&
 		    (bnx2_tx_avail(bp, txr) > bp->tx_wake_thresh))
 			netif_tx_wake_queue(txq);
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 28937f8..3e01ec6 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -508,7 +508,7 @@ static void txq_maybe_wake(struct tx_queue *txq)
 	struct netdev_queue *nq = netdev_get_tx_queue(mp->dev, txq->index);
 
 	if (netif_tx_queue_stopped(nq)) {
-		__netif_tx_lock(nq, (void *)current);
+		__netif_tx_lock(nq);
 		if (txq->tx_ring_size - txq->tx_desc_count >= MAX_SKB_FRAGS + 1)
 			netif_tx_wake_queue(nq);
 		__netif_tx_unlock(nq);
@@ -901,7 +901,7 @@ static void txq_kick(struct tx_queue *txq)
 	u32 hw_desc_ptr;
 	u32 expected_ptr;
 
-	__netif_tx_lock(nq, (void *)current);
+	__netif_tx_lock(nq);
 
 	if (rdlp(mp, TXQ_COMMAND) & (1 << txq->index))
 		goto out;
@@ -925,7 +925,7 @@ static int txq_reclaim(struct tx_queue *txq, int budget, int force)
 	struct netdev_queue *nq = netdev_get_tx_queue(mp->dev, txq->index);
 	int reclaimed;
 
-	__netif_tx_lock(nq, (void *)current);
+	__netif_tx_lock(nq);
 
 	reclaimed = 0;
 	while (reclaimed < budget && txq->tx_desc_count > 0) {
diff --git a/drivers/net/netxen/netxen_nic_init.c b/drivers/net/netxen/netxen_nic_init.c
index 64cff68..c4e38ca 100644
--- a/drivers/net/netxen/netxen_nic_init.c
+++ b/drivers/net/netxen/netxen_nic_init.c
@@ -1625,7 +1625,7 @@ int netxen_process_cmd_ring(struct netxen_adapter *adapter)
 		smp_mb();
 
 		if (netif_queue_stopped(netdev) && netif_carrier_ok(netdev)) {
-			__netif_tx_lock(tx_ring->txq, smp_processor_id());
+			__netif_tx_lock(tx_ring->txq);
 			if (netxen_tx_avail(tx_ring) > TX_STOP_THRESH) {
 				netif_wake_queue(netdev);
 				adapter->tx_timeo_cnt = 0;
diff --git a/drivers/net/niu.c b/drivers/net/niu.c
index 324d3ec..1cd2408 100644
--- a/drivers/net/niu.c
+++ b/drivers/net/niu.c
@@ -3677,7 +3677,7 @@ static void niu_tx_work(struct niu *np, struct tx_ring_info *rp)
 out:
 	if (unlikely(netif_tx_queue_stopped(txq) &&
 		     (niu_tx_avail(rp) > NIU_TX_WAKEUP_THRESH(rp)))) {
-		__netif_tx_lock(txq, (void *)current);
+		__netif_tx_lock(txq);
 		if (netif_tx_queue_stopped(txq) &&
 		    (niu_tx_avail(rp) > NIU_TX_WAKEUP_THRESH(rp)))
 			netif_tx_wake_queue(txq);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 787be1e..a3cbe54 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1745,10 +1745,18 @@ static inline u32 netif_msg_init(int debug_value, int default_msg_enable_bits)
 	return (1 << debug_value) - 1;
 }
 
-static inline void __netif_tx_lock(struct netdev_queue *txq, void *curr)
+static inline void __netif_tx_lock(struct netdev_queue *txq)
 {
 	spin_lock(&txq->_xmit_lock);
-	txq->xmit_lock_owner = curr;
+	txq->xmit_lock_owner = (void *)current;
+}
+
+/*
+ * Do we hold the xmit_lock already?
+ */
+static inline int netif_tx_lock_recursion(struct netdev_queue *txq)
+{
+	return txq->xmit_lock_owner == (void *)current;
 }
 
 static inline void __netif_tx_lock_bh(struct netdev_queue *txq)
@@ -1792,10 +1800,8 @@ static inline void txq_trans_update(struct netdev_queue *txq)
 static inline void netif_tx_lock(struct net_device *dev)
 {
 	unsigned int i;
-	void *curr;
 
 	spin_lock(&dev->tx_global_lock);
-	curr = (void *)current;
 	for (i = 0; i < dev->num_tx_queues; i++) {
 		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 
@@ -1805,7 +1811,7 @@ static inline void netif_tx_lock(struct net_device *dev)
 		 * the ->hard_start_xmit() handler and already
 		 * checked the frozen bit.
 		 */
-		__netif_tx_lock(txq, curr);
+		__netif_tx_lock(txq);
 		set_bit(__QUEUE_STATE_FROZEN, &txq->state);
 		__netif_tx_unlock(txq);
 	}
@@ -1840,9 +1846,9 @@ static inline void netif_tx_unlock_bh(struct net_device *dev)
 	local_bh_enable();
 }
 
-#define HARD_TX_LOCK(dev, txq, curr) {			\
+#define HARD_TX_LOCK(dev, txq) {			\
 	if ((dev->features & NETIF_F_LLTX) == 0) {	\
-		__netif_tx_lock(txq, curr);		\
+		__netif_tx_lock(txq);			\
 	}						\
 }
 
@@ -1855,14 +1861,12 @@ static inline void netif_tx_unlock_bh(struct net_device *dev)
 static inline void netif_tx_disable(struct net_device *dev)
 {
 	unsigned int i;
-	void *curr;
 
 	local_bh_disable();
-	curr = (void *)current;
 	for (i = 0; i < dev->num_tx_queues; i++) {
 		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 
-		__netif_tx_lock(txq, curr);
+		__netif_tx_lock(txq);
 		netif_tx_stop_queue(txq);
 		__netif_tx_unlock(txq);
 	}
diff --git a/net/core/dev.c b/net/core/dev.c
index ae8ca82..6a867ce 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2067,9 +2067,9 @@ gso:
 		/*
 		 * No need to check for recursion with threaded interrupts:
 		 */
-		if (txq->xmit_lock_owner != (void *)current) {
+		if (!netif_tx_lock_recursion(txq)) {
 
-			HARD_TX_LOCK(dev, txq, (void *)current);
+			HARD_TX_LOCK(dev, txq);
 
 			if (!netif_tx_queue_stopped(txq)) {
 				rc = dev_hard_start_xmit(skb, dev, txq);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 4f9c6d5..ffd4ecb 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -74,7 +74,7 @@ static void queue_process(struct work_struct *work)
 		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 
 		local_irq_save_nort(flags);
-		__netif_tx_lock(txq, (void *)current);
+		__netif_tx_lock(txq);
 		if (netif_tx_queue_stopped(txq) ||
 		    netif_tx_queue_frozen(txq) ||
 		    ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 420335b..0a18bbe 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -78,7 +78,7 @@ static inline int handle_dev_cpu_collision(struct sk_buff *skb,
 {
 	int ret;
 
-	if (unlikely(dev_queue->xmit_lock_owner == (void *)current)) {
+	if (unlikely(netif_tx_lock_recursion(dev_queue))) {
 		/*
 		 * Same CPU holding the lock. It may be a transient
 		 * configuration error, when hard_start_xmit() recurses. We
@@ -120,7 +120,7 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 	/* And release qdisc */
 	spin_unlock(root_lock);
 
-	HARD_TX_LOCK(dev, txq, (void *)current);
+	HARD_TX_LOCK(dev, txq);
 	if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq))
 		ret = dev_hard_start_xmit(skb, dev, txq);
 
-- 
1.7.1.1