On Wed, Oct 9, 2013 at 11:26 PM, Alexei Starovoitov <a...@plumgrid.com> wrote:
> On Wed, Oct 9, 2013 at 11:07 PM, Pravin Shelar <pshe...@nicira.com> wrote:
>> On Wed, Oct 9, 2013 at 9:11 PM, Alexei Starovoitov <a...@plumgrid.com> wrote:
>>> On Wed, Oct 9, 2013 at 8:02 PM, Pravin Shelar <pshe...@nicira.com> wrote:
>>>> On Tue, Oct 8, 2013 at 8:07 PM, Alexei Starovoitov <a...@plumgrid.com>
>>>> wrote:
>>>>> The combination of two commits
>>>>>
>>>>> commit 8e4e1713e4
>>>>> ("openvswitch: Simplify datapath locking.")
>>>>>
>>>>> and
>>>>>
>>>>> commit 2537b4dd0a
>>>>> ("openvswitch:: link upper device for port devices")
>>>>>
>>>>> introduced a bug where upper_dev wasn't unlinked upon
>>>>> netdev_unregister notification
>>>>>
>>>>> The following steps:
>>>>>
>>>>> modprobe openvswitch
>>>>> ovs-dpctl add-dp test
>>>>> ip tuntap add dev tap1 mode tap
>>>>> ovs-dpctl add-if test tap1
>>>>> ip tuntap del dev tap1 mode tap
>>>>>
>>>>> are causing multiple warnings:
>>>>> diff --git a/net/openvswitch/dp_notify.c b/net/openvswitch/dp_notify.c
>>>>> index c323567..e9380bd 100644
>>>>> --- a/net/openvswitch/dp_notify.c
>>>>> +++ b/net/openvswitch/dp_notify.c
>>>>> @@ -88,6 +88,11 @@ static int dp_device_event(struct notifier_block
>>>>> *unused, unsigned long event,
>>>>> return NOTIFY_DONE;
>>>>>
>>>>> if (event == NETDEV_UNREGISTER) {
>>>>> + /* rx_handler_unregister and upper_dev_unlink immediately
>>>>> */
>>>>> + if (dev->reg_state == NETREG_UNREGISTERING)
>>>>> + ovs_netdev_unlink_dev(vport);
>>>>> +
>>>>
>>>> Rather than doing vport destroy here, we can just unlink upper device
>>>> and let workq do rest of work.
>>>
>>> isn't it what it's doing?
>>
>> I meant just call netdev_upper_dev_unlink() here in event handler and
>> rest of vport destroy can be done in workq.
>
> netdev_upper_dev_unlink() without netdev_rx_handler_unregister() ?!
> that's dangerous.
why is it dangerous? ovs already had ref to net-device.
> If that is acceptable, then there was no reason to link them in the first
> place.
>
I do not see any harm in linking device hierarchy for ovs.
> notifier asks to unregister. imo the only acceptable deferred task
> here is to delay dev_put,
> since ovs structures are still referring to it.
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