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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/infiniband
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/infiniband')
-rw-r--r--drivers/infiniband/ulp/ipoib/ipoib_multicast.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index 1dae4b238252..1d917edcf9ba 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -821,7 +821,8 @@ void ipoib_mcast_restart_task(void *dev_ptr)
821 821
822 ipoib_mcast_stop_thread(dev, 0); 822 ipoib_mcast_stop_thread(dev, 0);
823 823
824 spin_lock_irqsave(&dev->xmit_lock, flags); 824 local_irq_save(flags);
825 netif_tx_lock(dev);
825 spin_lock(&priv->lock); 826 spin_lock(&priv->lock);
826 827
827 /* 828 /*
@@ -896,7 +897,8 @@ void ipoib_mcast_restart_task(void *dev_ptr)
896 } 897 }
897 898
898 spin_unlock(&priv->lock); 899 spin_unlock(&priv->lock);
899 spin_unlock_irqrestore(&dev->xmit_lock, flags); 900 netif_tx_unlock(dev);
901 local_irq_restore(flags);
900 902
901 /* We have to cancel outside of the spinlock */ 903 /* We have to cancel outside of the spinlock */
902 list_for_each_entry_safe(mcast, tmcast, &remove_list, list) { 904 list_for_each_entry_safe(mcast, tmcast, &remove_list, list) {