From: ebiederm@xmission•com (Eric W. Biederman)
To: Johannes Berg <johannes@sipsolutions•net>
Cc: Greg KH <greg@kroah•com>, netdev <netdev@vger•kernel.org>
Subject: Re: sysfs class/net/ problem
Date: Wed, 02 Jun 2010 09:43:22 -0700 [thread overview]
Message-ID: <m14ohlxu51.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <1275495677.3915.16.camel@jlt3.sipsolutions.net> (Johannes Berg's message of "Wed\, 02 Jun 2010 18\:21\:17 +0200")
Johannes Berg <johannes@sipsolutions•net> writes:
> On Wed, 2010-06-02 at 09:17 -0700, Eric W. Biederman wrote:
>
>> >> Ah, so the network devices aren't getting removed?
>> >
>> > Well the netdevs are gone, just the links aren't going away. the
>> > mac80211_hwsim directory is gone too.
>> >
>> >> Do you have network namespaces enabled in your kernel or disabled?
>> >
>> > enabled
>> >
>> >> And this is 2.6.35-rc1, right?
>> >
>> > yes.
>> >
>> > Come to think of it, maybe somehow it ends up removing
>> > mac80211_hwsim/hwsim0 before wlan0, and thus the link stays around? I
>> > guess I could make it print messages about that somehow?
>>
>> The wireless drivers are a little different, and come to think of it
>> network namespace support has been added to the wireless drivers since
>> last I looked closely.
>
> Yeah, I now need to go add tagged sysfs support to it too.
>
>> Do you know what creates/deletes these links?
>> Is it the normal register_netdevice -> device_add path?
>
> Yes, they aren't done specially.
>> I definitely changed the symlink code a little making things network namespace
>> aware so it is reasonable to assume that something in my changes affected the
>> wireless drivers.
>
>> I took a quick look and with my patches against 2.6.33 I'm not seeing this.
>
> Hmm. I'm also not seeing it with veth, it would seem that ought to be
> similar?
Since it is the register_netdev path it should be exactly the same.
The big change I made is I in some instances I replaced
sysfs_remove_link with sysfs_delete_link so I could have enough
information to infer which network namespace the link was in. Since
wlan0 is a netdevice all of that information should already be there.
>> I take a closer look at 2.6.35-rc1 and see if I can figure out what is
>> going on. It would definitely be wrong if hwsim0 is removed before
>> wlan0.
>
> I don't know if that's happening .. just guessing that it might cause
> such a problem, and maybe some things are deferred somehow? Since netdev
> destruction can be deferred, but the wifi sysfs destruction isn't. But
> then that link there should cause the refcount to not go down until the
> link goes away>?
unregister_netdevice will defer the final destruction but it does not
defer netdev_unregister_kobject -> device_del.
What happens if in exit_mac80211_hwsim you call unregister_netdev before
mac80211_hwsim_free?
At a quick glance it simply looks like you have the ordering reversed in your
module cleanup, and this is not network namespace related at all.
Eric
next prev parent reply other threads:[~2010-06-02 16:43 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-02 13:16 sysfs class/net/ problem Johannes Berg
2010-06-02 15:46 ` Greg KH
2010-06-02 15:48 ` Johannes Berg
2010-06-02 16:17 ` Eric W. Biederman
2010-06-02 16:21 ` Johannes Berg
2010-06-02 16:43 ` Eric W. Biederman [this message]
2010-06-02 17:00 ` Johannes Berg
2010-06-02 17:23 ` Eric W. Biederman
2010-06-02 17:52 ` Johannes Berg
2010-06-02 18:05 ` Eric W. Biederman
2010-06-02 18:55 ` Johannes Berg
2010-06-02 19:12 ` Johannes Berg
2010-06-02 19:25 ` Johannes Berg
2010-06-02 23:09 ` Eric W. Biederman
2010-06-03 0:53 ` [RFC][PATCH] Fix another namespace issue with devices assigned to classes Eric W. Biederman
2010-06-03 9:30 ` Kay Sievers
2010-06-03 10:00 ` Eric W. Biederman
2010-06-04 6:54 ` Johannes Berg
2010-06-04 8:15 ` Kay Sievers
2010-06-04 8:28 ` Johannes Berg
2010-06-04 8:34 ` Kay Sievers
2010-06-06 13:08 ` Johannes Berg
2010-06-06 17:17 ` Kay Sievers
2010-06-07 9:42 ` Johannes Berg
2010-06-07 9:53 ` Kay Sievers
2010-06-07 10:14 ` Johannes Berg
2010-06-07 11:05 ` Kay Sievers
2010-06-07 11:41 ` Johannes Berg
2010-06-07 12:26 ` Kay Sievers
2010-06-07 12:36 ` Johannes Berg
2010-06-07 12:54 ` Kay Sievers
2010-06-08 9:27 ` Johannes Berg
2010-06-08 9:30 ` Kay Sievers
2010-06-08 9:45 ` Johannes Berg
2010-06-08 11:55 ` Kay Sievers
2010-06-08 12:03 ` Johannes Berg
2010-06-08 13:54 ` Kay Sievers
2010-06-08 14:06 ` Johannes Berg
2010-06-08 14:21 ` Kay Sievers
2010-06-08 14:26 ` Johannes Berg
2010-06-08 14:47 ` Kay Sievers
2010-06-08 15:06 ` Johannes Berg
2010-06-08 16:26 ` Kay Sievers
2010-06-08 16:33 ` Johannes Berg
2010-06-08 16:39 ` Kay Sievers
2010-06-11 9:55 ` Johannes Berg
2010-06-14 9:13 ` Kay Sievers
2010-06-14 9:20 ` Johannes Berg
2010-06-14 9:39 ` Kay Sievers
2010-06-20 6:20 ` [PATCH] Driver-core: Always create class directories fixing the broken network drivers Eric W. Biederman
2010-06-20 10:52 ` Kay Sievers
2010-06-20 11:33 ` Johannes Berg
2010-06-20 11:46 ` Kay Sievers
2010-06-20 12:29 ` Eric W. Biederman
2010-06-20 13:37 ` Kay Sievers
2010-06-20 12:46 ` [PATCH] Driver-core: Always create network class directories in get_device_parent Eric W. Biederman
2010-06-21 22:20 ` Greg KH
2010-06-21 23:00 ` Eric W. Biederman
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