This finally adds the code in net_rx_action() to break out of the
->poll()'ing loop when a napi_disable() is found to be pending.

Now, even if a device is being flooded with packets it can be cleanly
brought down.

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

There are some return value comments for void functions.
Fixed it.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit fcc5a03ac42564e9e255c1134dda47442289e466:

	[NET]: Allow netdev REGISTER/CHANGENAME events to fail

makes the register_netdevice_notifier() handle the error from the
NETDEV_REGISTER event, sent to the registering block.

The bad news is that in this case the notifier block is 
not removed from the list, but the error is returned to the 
caller. In case the caller is in module init function and 
handles this error this can abort the module loading. The
notifier block will be then removed from the kernel, but 
will be left in the list. Oops :(

I think that the notifier block should be removed from the
chain in case of error, regardless whether this error is 
handled by the caller or not. In the worst case (the error 
is _not_ handled) module will not receive the events any 
longer.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch reverts Eric's commit 2b008b0a8e96b726c603c5e1a5a7a509b5f61e35

It diets .text & .data section of the kernel if CONFIG_NET_NS is not set.
This is safe after list operations cleanup.

Signed-of-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

* it already statically initialized
* reinitializing live global spinlock every time netns is
  setup is also wrong

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation updates for network interfaces.

1. Add doc for netif_napi_add
2. Remove doc for unused returns from netif_rx
3. Add doc for netif_receive_skb

[ Incorporated minor mods from Randy Dunlap -DaveM ]

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Point 1:
The unregistering of a network device schedule a netdev_run_todo.
This function calls dev->destructor when it is set and the
destructor calls free_netdev.

Point 2:
In the case of an initialization of a network device the usual code
is:
 * alloc_netdev
 * register_netdev
    -> if this one fails, call free_netdev and exit with error.

Point 3:
In the register_netdevice function at the later state, when the device
is at the registered state, a call to the netdevice_notifiers is made.
If one of the notification falls into an error, a rollback to the
registered state is done using unregister_netdevice.

Conclusion:
When a network device fails to register during initialization because
one network subsystem returned an error during a notification call
chain, the network device is freed twice because of fact 1 and fact 2.
The second free_netdev will be done with an invalid pointer.

Proposed solution:
The following patch move all the code of unregister_netdevice *except*
the call to net_set_todo, to a new function "rollback_registered".

The following functions are changed in this way:
 * register_netdevice: calls rollback_registered when a notification fails
 * unregister_netdevice: calls rollback_register + net_set_todo, the call
                         order to net_set_todo is changed because it is the
                         latest now. Since it justs add an element to a list
                         that should not break anything.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netpoll_poll_lock() synchronizes the ->poll() invocation
code paths, but once we have the lock we have to make
sure that NAPI_STATE_SCHED is still set.  Otherwise we
get:

	cpu 0			cpu 1

	net_rx_action()		poll_napi()
	netpoll_poll_lock()	... spin on ->poll_lock
	->poll()
	  netif_rx_complete
	netpoll_poll_unlock()	acquire ->poll_lock()
				->poll()
				 netif_rx_complete()
				 CRASH

Based upon a bug report from Tina Yang.

Signed-off-by: David S. Miller <davem@davemloft.net>

It is not safe to to place struct pernet_operations in a special section.
We need struct pernet_operations to last until we call unregister_pernet_subsys.
Which doesn't happen until module unload.

So marking struct pernet_operations is a disaster for modules in two ways.
- We discard it before we call the exit method it points to.
- Because I keep struct pernet_operations on a linked list discarding
  it for compiled in code removes elements in the middle of a linked
  list and does horrible things for linked insert.

So this looks safe assuming __exit_refok is not discarded
for modules.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>