diff options
author | Michael Chan <mchan@broadcom.com> | 2006-06-17 21:58:45 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2006-06-17 21:58:45 -0700 |
commit | 00b7050426da8e7e58c889c5c80a19920d2d41b3 (patch) | |
tree | 55a07464fdf81b23fced966feca2b041af77c6f6 | |
parent | c71302d61f844f766a44e1b04258086cc41f624e (diff) | |
download | lwn-00b7050426da8e7e58c889c5c80a19920d2d41b3.tar.gz lwn-00b7050426da8e7e58c889c5c80a19920d2d41b3.zip |
[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: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | drivers/net/tg3.c | 27 | ||||
-rw-r--r-- | drivers/net/tg3.h | 16 |
2 files changed, 23 insertions, 20 deletions
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c index 542d4c3a10e5..b2ddd4522a87 100644 --- a/drivers/net/tg3.c +++ b/drivers/net/tg3.c @@ -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; diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h index 35669e18065c..8209da5dd15f 100644 --- a/drivers/net/tg3.h +++ b/drivers/net/tg3.h @@ -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; |