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authorHerbert Xu <herbert@gondor.apana.org.au>2006-06-09 15:20:56 -0400
committerDavid S. Miller <davem@sunset.davemloft.net>2006-06-18 00:30:14 -0400
commit932ff279a43ab7257942cddff2595acd541cc49b (patch)
treee60130673a20d71becdac858c2589d8dfbf3ae1f /drivers/net/tulip/winbond-840.c
parentbf0857ea32addb6bc8b46383604b218b8ec09f19 (diff)
[NET]: Add netif_tx_lock
Various drivers use xmit_lock internally to synchronise with their transmission routines. They do so without setting xmit_lock_owner. This is fine as long as netpoll is not in use. With netpoll it is possible for deadlocks to occur if xmit_lock_owner isn't set. This is because if a printk occurs while xmit_lock is held and xmit_lock_owner is not set can cause netpoll to attempt to take xmit_lock recursively. While it is possible to resolve this by getting netpoll to use trylock, it is suboptimal because netpoll's sole objective is to maximise the chance of getting the printk out on the wire. So delaying or dropping the message is to be avoided as much as possible. So the only alternative is to always set xmit_lock_owner. The following patch does this by introducing the netif_tx_lock family of functions that take care of setting/unsetting xmit_lock_owner. I renamed xmit_lock to _xmit_lock to indicate that it should not be used directly. I didn't provide irq versions of the netif_tx_lock functions since xmit_lock is meant to be a BH-disabling lock. This is pretty much a straight text substitution except for a small bug fix in winbond. It currently uses netif_stop_queue/spin_unlock_wait to stop transmission. This is unsafe as an IRQ can potentially wake up the queue. So it is safer to use netif_tx_disable. The hamradio bits used spin_lock_irq but it is unnecessary as xmit_lock must never be taken in an IRQ handler. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tulip/winbond-840.c')
-rw-r--r--drivers/net/tulip/winbond-840.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/net/tulip/winbond-840.c b/drivers/net/tulip/winbond-840.c
index 136a70c4d5e4..56d86c7c0386 100644
--- a/drivers/net/tulip/winbond-840.c
+++ b/drivers/net/tulip/winbond-840.c
@@ -1605,11 +1605,11 @@ static void __devexit w840_remove1 (struct pci_dev *pdev)
1605 * - get_stats: 1605 * - get_stats:
1606 * spin_lock_irq(np->lock), doesn't touch hw if not present 1606 * spin_lock_irq(np->lock), doesn't touch hw if not present
1607 * - hard_start_xmit: 1607 * - hard_start_xmit:
1608 * netif_stop_queue + spin_unlock_wait(&dev->xmit_lock); 1608 * synchronize_irq + netif_tx_disable;
1609 * - tx_timeout: 1609 * - tx_timeout:
1610 * netif_device_detach + spin_unlock_wait(&dev->xmit_lock); 1610 * netif_device_detach + netif_tx_disable;
1611 * - set_multicast_list 1611 * - set_multicast_list
1612 * netif_device_detach + spin_unlock_wait(&dev->xmit_lock); 1612 * netif_device_detach + netif_tx_disable;
1613 * - interrupt handler 1613 * - interrupt handler
1614 * doesn't touch hw if not present, synchronize_irq waits for 1614 * doesn't touch hw if not present, synchronize_irq waits for
1615 * running instances of the interrupt handler. 1615 * running instances of the interrupt handler.
@@ -1635,11 +1635,10 @@ static int w840_suspend (struct pci_dev *pdev, pm_message_t state)
1635 netif_device_detach(dev); 1635 netif_device_detach(dev);
1636 update_csr6(dev, 0); 1636 update_csr6(dev, 0);
1637 iowrite32(0, ioaddr + IntrEnable); 1637 iowrite32(0, ioaddr + IntrEnable);
1638 netif_stop_queue(dev);
1639 spin_unlock_irq(&np->lock); 1638 spin_unlock_irq(&np->lock);
1640 1639
1641 spin_unlock_wait(&dev->xmit_lock);
1642 synchronize_irq(dev->irq); 1640 synchronize_irq(dev->irq);
1641 netif_tx_disable(dev);
1643 1642
1644 np->stats.rx_missed_errors += ioread32(ioaddr + RxMissed) & 0xffff; 1643 np->stats.rx_missed_errors += ioread32(ioaddr + RxMissed) & 0xffff;
1645 1644