Commit e93737b0 authored Dec 08, 2009 by Krishna Kumar Committed by David S. Miller Dec 11, 2009

net: Handle NETREG_UNINITIALIZED devices correctly



Fix two problems:

1. If unregister_netdevice_many() is called with both registered
   and unregistered devices, rollback_registered_many() bails out
   when it reaches the first unregistered device. The processing
   of the prior registered devices is unfinished, and the
   remaining devices are skipped, and possible registered netdev's
   are leaked/unregistered.

2. System hangs or panics depending on how the devices are passed,
   since when netdev_run_todo() runs, some devices were not fully
   processed.

Tested by passing intermingled unregistered and registered vlan
devices to unregister_netdevice_many() as follows:
	1. dev, fake_dev1, fake_dev2: hangs in run_todo
	   ("unregister_netdevice: waiting for eth1.100 to become
	    free. Usage count = 1")
	2. fake_dev1, dev, fake_dev2: failure during de-registration
	   and next registration, followed by a vlan driver Oops
	   during subsequent registration.

Confirmed that the patch fixes both cases.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent bbb84619

net/core/dev.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -4771,21 +4771,23 @@ static void net_set_todo(struct net_device *dev)

		static void rollback_registered_many(struct list_head *head)
		{
		struct net_device *dev;
		struct net_device dev, tmp;

		BUG_ON(dev_boot_phase);
		ASSERT_RTNL();

		list_for_each_entry(dev, head, unreg_list) {
		list_for_each_entry_safe(dev, tmp, head, unreg_list) {
		/* Some devices call without registering
		* for initialization unwind.
		* for initialization unwind. Remove those
		* devices and proceed with the remaining.
		*/
		if (dev->reg_state == NETREG_UNINITIALIZED) {
		pr_debug("unregister_netdevice: device %s/%p never "
		"was registered\n", dev->name, dev);

		WARN_ON(1);
		return;
		list_del(&dev->unreg_list);
		continue;
		}

		BUG_ON(dev->reg_state != NETREG_REGISTERED);

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