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Commit 00b70504 authored by Michael Chan's avatar Michael Chan Committed by David S. Miller
Browse files

[TG3]: Convert to non-LLTX 



Herbert Xu pointed out that it is unsafe to call netif_tx_disable()
from LLTX drivers because it uses dev->xmit_lock to synchronize
whereas LLTX drivers use private locks.

Convert tg3 to non-LLTX to fix this issue. tg3 is a lockless driver
where hard_start_xmit and tx completion handling can run concurrently
under normal conditions. A tx_lock is only needed to prevent
netif_stop_queue and netif_wake_queue race condtions when the queue
is full.

So whether we use LLTX or non-LLTX, it makes practically no
difference.

Signed-off-by: default avatarMichael Chan <mchan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c71302d6

drivers/net/tg3.c

+10 −17
Original line number Diff line number Diff line
@@ -3759,14 +3759,11 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 


	len = skb_headlen(skb);



	/* No BH disabling for tx_lock here.  We are running in BH disabled

	 * context and TX reclaim runs via tp->poll inside of a software

	/* We are running in BH disabled context with netif_tx_lock

	 * and TX reclaim runs via tp->poll inside of a software

	 * interrupt.  Furthermore, IRQ processing runs lockless so we have

	 * no IRQ context deadlocks to worry about either.  Rejoice!

	 */

	if (!spin_trylock(&tp->tx_lock))

		return NETDEV_TX_LOCKED;



	if (unlikely(TX_BUFFS_AVAIL(tp) <= (skb_shinfo(skb)->nr_frags + 1))) {

		if (!netif_queue_stopped(dev)) {

			netif_stop_queue(dev);
@@ -3775,7 +3772,6 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 
			printk(KERN_ERR PFX "%s: BUG! Tx Ring full when "

			       "queue awake!\n", dev->name);

		}

		spin_unlock(&tp->tx_lock);

		return NETDEV_TX_BUSY;

	}
@@ -3858,15 +3854,16 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	tw32_tx_mbox((MAILBOX_SNDHOST_PROD_IDX_0 + TG3_64BIT_REG_LOW), entry);



	tp->tx_prod = entry;

	if (TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1)) {

	if (unlikely(TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1))) {

		spin_lock(&tp->tx_lock);

		netif_stop_queue(dev);

		if (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH)

			netif_wake_queue(tp->dev);

		spin_unlock(&tp->tx_lock);

	}



out_unlock:

    	mmiowb();

	spin_unlock(&tp->tx_lock);



	dev->trans_start = jiffies;
@@ -3885,14 +3882,11 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev) 


	len = skb_headlen(skb);



	/* No BH disabling for tx_lock here.  We are running in BH disabled

	 * context and TX reclaim runs via tp->poll inside of a software

	/* We are running in BH disabled context with netif_tx_lock

	 * and TX reclaim runs via tp->poll inside of a software

	 * interrupt.  Furthermore, IRQ processing runs lockless so we have

	 * no IRQ context deadlocks to worry about either.  Rejoice!

	 */

	if (!spin_trylock(&tp->tx_lock))

		return NETDEV_TX_LOCKED; 



	if (unlikely(TX_BUFFS_AVAIL(tp) <= (skb_shinfo(skb)->nr_frags + 1))) {

		if (!netif_queue_stopped(dev)) {

			netif_stop_queue(dev);
@@ -3901,7 +3895,6 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev) 
			printk(KERN_ERR PFX "%s: BUG! Tx Ring full when "

			       "queue awake!\n", dev->name);

		}

		spin_unlock(&tp->tx_lock);

		return NETDEV_TX_BUSY;

	}
@@ -4039,15 +4032,16 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev) 
	tw32_tx_mbox((MAILBOX_SNDHOST_PROD_IDX_0 + TG3_64BIT_REG_LOW), entry);



	tp->tx_prod = entry;

	if (TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1)) {

	if (unlikely(TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1))) {

		spin_lock(&tp->tx_lock);

		netif_stop_queue(dev);

		if (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH)

			netif_wake_queue(tp->dev);

		spin_unlock(&tp->tx_lock);

	}



out_unlock:

    	mmiowb();

	spin_unlock(&tp->tx_lock);



	dev->trans_start = jiffies;
@@ -11284,7 +11278,6 @@ static int __devinit tg3_init_one(struct pci_dev *pdev, 
	SET_MODULE_OWNER(dev);

	SET_NETDEV_DEV(dev, &pdev->dev);



	dev->features |= NETIF_F_LLTX;

#if TG3_VLAN_TAG_USED

	dev->features |= NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_RX;

	dev->vlan_rx_register = tg3_vlan_rx_register;

drivers/net/tg3.h

+13 −3
Original line number Diff line number Diff line
@@ -2074,12 +2074,22 @@ struct tg3 { 


	/* SMP locking strategy:

	 *

	 * lock: Held during all operations except TX packet

	 *       processing.

	 * lock: Held during reset, PHY access, timer, and when

	 *       updating tg3_flags and tg3_flags2.

	 *

	 * tx_lock: Held during tg3_start_xmit and tg3_tx

	 * tx_lock: Held during tg3_start_xmit and tg3_tx only

	 *          when calling netif_[start|stop]_queue.

	 *          tg3_start_xmit is protected by netif_tx_lock.

	 *

	 * Both of these locks are to be held with BH safety.

	 *

	 * Because the IRQ handler, tg3_poll, and tg3_start_xmit

	 * are running lockless, it is necessary to completely

	 * quiesce the chip with tg3_netif_stop and tg3_full_lock

	 * before reconfiguring the device.

	 *

	 * indirect_lock: Held when accessing registers indirectly

	 *                with IRQ disabling.

	 */

	spinlock_t			lock;

	spinlock_t			indirect_lock;