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authorEric Dumazet <edumazet@google.com>2012-08-22 17:19:46 +0000
committerDavid S. Miller <davem@davemloft.net>2012-08-22 21:50:36 -0700
commit0115e8e30d6fcdd4b8faa30d3ffd90859a591f51 (patch)
tree725026e2192e57b98366947ab53c73689ca040a8 /net/core/dev.c
parentbf277b0ccea7d2422b85e232017ce3fddbe9c49c (diff)
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net: remove delay at device dismantle
I noticed extra one second delay in device dismantle, tracked down to a call to dst_dev_event() while some call_rcu() are still in RCU queues. These call_rcu() were posted by rt_free(struct rtable *rt) calls. We then wait a little (but one second) in netdev_wait_allrefs() before kicking again NETDEV_UNREGISTER. As the call_rcu() are now completed, dst_dev_event() can do the needed device swap on busy dst. To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called after a rcu_barrier(), but outside of RTNL lock. Use NETDEV_UNREGISTER_FINAL with care ! Change dst_dev_event() handler to react to NETDEV_UNREGISTER_FINAL Also remove NETDEV_UNREGISTER_BATCH, as its not used anymore after IP cache removal. With help from Gao feng Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Mahesh Bandewar <maheshb@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Gao feng <gaofeng@cn.fujitsu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
-rw-r--r--net/core/dev.c22
1 files changed, 8 insertions, 14 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 088923f..0640d2a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1406,7 +1406,6 @@ rollback:
nb->notifier_call(nb, NETDEV_DOWN, dev);
}
nb->notifier_call(nb, NETDEV_UNREGISTER, dev);
- nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev);
}
}
@@ -1448,7 +1447,6 @@ int unregister_netdevice_notifier(struct notifier_block *nb)
nb->notifier_call(nb, NETDEV_DOWN, dev);
}
nb->notifier_call(nb, NETDEV_UNREGISTER, dev);
- nb->notifier_call(nb, NETDEV_UNREGISTER_BATCH, dev);
}
}
unlock:
@@ -1468,7 +1466,8 @@ EXPORT_SYMBOL(unregister_netdevice_notifier);
int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
{
- ASSERT_RTNL();
+ if (val != NETDEV_UNREGISTER_FINAL)
+ ASSERT_RTNL();
return raw_notifier_call_chain(&netdev_chain, val, dev);
}
EXPORT_SYMBOL(call_netdevice_notifiers);
@@ -5331,10 +5330,6 @@ static void rollback_registered_many(struct list_head *head)
netdev_unregister_kobject(dev);
}
- /* Process any work delayed until the end of the batch */
- dev = list_first_entry(head, struct net_device, unreg_list);
- call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);
-
synchronize_net();
list_for_each_entry(dev, head, unreg_list)
@@ -5787,9 +5782,8 @@ static void netdev_wait_allrefs(struct net_device *dev)
/* Rebroadcast unregister notification */
call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
- /* don't resend NETDEV_UNREGISTER_BATCH, _BATCH users
- * should have already handle it the first time */
-
+ rcu_barrier();
+ call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
&dev->state)) {
/* We must not have linkwatch events
@@ -5851,9 +5845,8 @@ void netdev_run_todo(void)
__rtnl_unlock();
- /* Wait for rcu callbacks to finish before attempting to drain
- * the device list. This usually avoids a 250ms wait.
- */
+
+ /* Wait for rcu callbacks to finish before next phase */
if (!list_empty(&list))
rcu_barrier();
@@ -5862,6 +5855,8 @@ void netdev_run_todo(void)
= list_first_entry(&list, struct net_device, todo_list);
list_del(&dev->todo_list);
+ call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
+
if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
pr_err("network todo '%s' but state %d\n",
dev->name, dev->reg_state);
@@ -6256,7 +6251,6 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
the device is just moving and can keep their slaves up.
*/
call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
- call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);
rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
/*
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