diff options
authorHerbert Xu <herbert@gondor.apana.org.au>2006-06-22 02:28:18 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2006-06-23 02:07:26 -0700
commitd4828d85d188dc70ed172802e798d3978bb6e29e (patch)
parent[IPV6] ADDRCONF: Fix default source address selection without CONFIG_IPV6_PRIVACY (diff)
[NET]: Prevent transmission after dev_deactivate
The dev_deactivate function has bit-rotted since the introduction of lockless drivers. In particular, the spin_unlock_wait call at the end has no effect on the xmit routine of lockless drivers. With a little bit of work, we can make it much more useful by providing the guarantee that when it returns, no more calls to the xmit routine of the underlying driver will be made. The idea is simple. There are two entry points in to the xmit routine. The first comes from dev_queue_xmit. That one is easily stopped by using synchronize_rcu. This works because we set the qdisc to noop_qdisc before the synchronize_rcu call. That in turn causes all subsequent packets sent to dev_queue_xmit to be dropped. The synchronize_rcu call also ensures all outstanding calls leave their critical section. The other entry point is from qdisc_run. Since we now have a bit that indicates whether it's running, all we have to do is to wait until the bit is off. I've removed the loop to wait for __LINK_STATE_SCHED to clear. This is useless because netif_wake_queue can cause it to be set again. It is also harmless because we've disarmed qdisc_run. I've also removed the spin_unlock_wait on xmit_lock because its only purpose of making sure that all outstanding xmit_lock holders have exited is also given by dev_watchdog_down. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2 files changed, 12 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index ab39fe17cb58..29e3888102bc 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1295,7 +1295,7 @@ int dev_queue_xmit(struct sk_buff *skb)
/* Disable soft irqs for various locks below. Also
* stops preemption for RCU.
- local_bh_disable();
+ rcu_read_lock_bh();
/* Updates of qdisc are serialized by queue_lock.
* The struct Qdisc which is pointed to by qdisc is now a
@@ -1369,13 +1369,13 @@ int dev_queue_xmit(struct sk_buff *skb)
- local_bh_enable();
+ rcu_read_unlock_bh();
return rc;
- local_bh_enable();
+ rcu_read_unlock_bh();
return rc;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index d7aca8ef524a..7aad0121232c 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -181,9 +181,13 @@ requeue:
void __qdisc_run(struct net_device *dev)
+ if (unlikely(dev->qdisc == &noop_qdisc))
+ goto out;
while (qdisc_restart(dev) < 0 && !netif_queue_stopped(dev))
/* NOTHING */;
clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
@@ -583,10 +587,12 @@ void dev_deactivate(struct net_device *dev)
- while (test_bit(__LINK_STATE_SCHED, &dev->state))
- yield();
+ /* Wait for outstanding dev_queue_xmit calls. */
+ synchronize_rcu();
- spin_unlock_wait(&dev->_xmit_lock);
+ /* Wait for outstanding qdisc_run calls. */
+ while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
+ yield();
void dev_init_scheduler(struct net_device *dev)