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[TG3]: Convert to non-LLTX

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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: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael Chan 2006-06-17 21:58:45 -07:00 committed by David S. Miller
parent c71302d61f
commit 00b7050426
2 changed files with 23 additions and 20 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
drivers/net/tg3.c
View file

@ -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;

16
drivers/net/tg3.h
View file

@ -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;