netdev - Re: [PATCH net-next] openvswitch: fix vport-netdev unregister

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 9 Oct 2013 23:26:28 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Pravin Shelar <pshelar@...ira.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Jesse Gross <jesse@...ira.com>, Jiri Pirko <jiri@...nulli.us>,
	"dev@...nvswitch.org" <dev@...nvswitch.org>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] openvswitch: fix vport-netdev unregister

On Wed, Oct 9, 2013 at 11:07 PM, Pravin Shelar <pshelar@...ira.com> wrote:
> On Wed, Oct 9, 2013 at 9:11 PM, Alexei Starovoitov <ast@...mgrid.com> wrote:
>> On Wed, Oct 9, 2013 at 8:02 PM, Pravin Shelar <pshelar@...ira.com> wrote:
>>> On Tue, Oct 8, 2013 at 8:07 PM, Alexei Starovoitov <ast@...mgrid.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.
If that is acceptable, then there was no reason to link them in the first place.

notifier asks to unregister. imo the only acceptable deferred task
here is to delay dev_put,
since ovs structures are still referring to it.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html