From: Johannes Berg <johannes@sipsolutions.net>
To: Taehee Yoo <ap420073@gmail.com>
Cc: "David Miller" <davem@davemloft.net>,
Netdev <netdev@vger.kernel.org>,
linux-wireless@vger.kernel.org,
"Jakub Kicinski" <jakub.kicinski@netronome.com>,
j.vosburgh@gmail.com, vfalico@gmail.com,
"Andy Gospodarek" <andy@greyhouse.net>,
"Jiří Pírko" <jiri@resnulli.us>,
sd@queasysnail.net, "Roopa Prabhu" <roopa@cumulusnetworks.com>,
saeedm@mellanox.com, manishc@marvell.com, rahulv@marvell.com,
kys@microsoft.com, haiyangz@microsoft.com,
"Stephen Hemminger" <stephen@networkplumber.org>,
sashal@kernel.org, hare@suse.de, varun@chelsio.com,
ubraun@linux.ibm.com, kgraul@linux.ibm.com,
"Jay Vosburgh" <jay.vosburgh@canonical.com>,
"Cody Schuffelen" <schuffelen@google.com>,
bjorn@mork.no
Subject: Re: [PATCH net v4 00/12] net: fix nested device bugs
Date: Tue, 01 Oct 2019 09:39:07 +0200 [thread overview]
Message-ID: <1b17084d8649bab347b952231d9312b7fb7307f4.camel@sipsolutions.net> (raw)
In-Reply-To: <CAMArcTWs3wzad7ai_zQPCwzC62cFp-poELn+jnDaP7eT1a9ucw@mail.gmail.com> (sfid-20190929_103128_233294_188E5AB3)
On Sun, 2019-09-29 at 17:31 +0900, Taehee Yoo wrote:
> virt_wifi case is a little bit different case.
Well, arguably, it was also just missing this - it just looks different
:)
> I add the last patch that is to fix refcnt leaks in the virt_wifi module.
> The way to fix this is to add notifier routine.
> The notifier routine could delete lower device before deleting
> virt_wifi device.
> If virt_wifi devices are nested, notifier would work recursively.
> At that time, it would make stack memory overflow.
>
> Actually, before this patch, virt_wifi doesn't have the same problem.
> So, I will update a comment in a v5 patch.
OK, sure.
> Many other devices use this way to avoid wrong nesting configuration.
> And I think it's a good way.
> But we should think about the below configuration.
>
> vlan5
> |
> virt_wifi4
> |
> vlan3
> |
> virt_wifi2
> |
> vlan1
> |
> dummy0
>
> That code wouldn't avoid this configuration.
> And all devices couldn't avoid this config.
Good point, so then really that isn't useful to check - most people
won't try to set it up that way (since it's completely useless) and if
they do anyway too much nesting would be caught by your patchset here.
> I have been considering this case, but I couldn't make a decision yet.
> Maybe common netdev function is needed to find the same device type
> in their graph.
I don't think it's worthwhile just to prevent somebody from making a
configuration that we think now is nonsense. Perhaps they do have some
kind of useful use-case for it ...
> This is a little bit different question for you.
> I found another bug in virt_wifi after my last patch.
> Please test below commands
> ip link add dummy0 type dummy
> ip link add vw1 link dummy0 type virt_wifi
> ip link add vw2 link vw1 type virt_wifi
> modprobe -rv virt_wifi
>
> Then, you can see the warning messages.
> If SET_NETDEV_DEV() is deleted in the virt_wifi_newlink(),
> you can avoid that warning message.
> But I'm not sure about it's safe to remove that.
> I would really appreciate it if you let me know about that.
Hmm, I don't see any warnings. SET_NETDEV_DEV() should be there though.
Do you see the same if you stack it with something else inbetween? If
not, I guess preventing virt_wifi from stacking on top of itself would
be sufficient ...
johannes
next prev parent reply other threads:[~2019-10-01 7:39 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-28 16:48 [PATCH net v4 00/12] net: fix nested device bugs Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 01/12] net: core: limit nested device depth Taehee Yoo
2019-09-28 19:36 ` Johannes Berg
2019-09-29 11:05 ` Taehee Yoo
2019-10-01 7:11 ` Johannes Berg
2019-10-01 13:53 ` Taehee Yoo
2019-10-01 13:57 ` Johannes Berg
2019-10-01 18:23 ` Taehee Yoo
2019-10-10 10:19 ` Sabrina Dubroca
2019-10-12 11:42 ` Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 02/12] vlan: use dynamic lockdep key instead of subclass Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 03/12] bonding: fix unexpected IFF_BONDING bit unset Taehee Yoo
2019-09-30 20:48 ` Jay Vosburgh
2019-09-28 16:48 ` [PATCH net v4 04/12] bonding: use dynamic lockdep key instead of subclass Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 05/12] team: use dynamic lockdep key instead of static key Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 06/12] macsec: use dynamic lockdep key instead of subclass Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 07/12] macvlan: " Taehee Yoo
2019-09-28 19:14 ` Johannes Berg
2019-09-29 8:03 ` Taehee Yoo
2019-10-01 7:25 ` Johannes Berg
2019-10-05 9:13 ` Taehee Yoo
2019-10-07 11:41 ` Johannes Berg
2019-10-08 8:13 ` Taehee Yoo
2019-10-21 16:00 ` Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 08/12] macsec: fix refcnt leak in module exit routine Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 09/12] net: core: add ignore flag to netdev_adjacent structure Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 10/12] vxlan: add adjacent link to limit depth level Taehee Yoo
2019-09-28 16:48 ` [PATCH net v4 11/12] net: remove unnecessary variables and callback Taehee Yoo
2019-09-28 19:42 ` Johannes Berg
2019-09-28 16:48 ` [PATCH net v4 12/12] virt_wifi: fix refcnt leak in module exit routine Taehee Yoo
2019-09-28 18:57 ` Johannes Berg
2019-10-07 11:22 ` Sabrina Dubroca
2019-10-08 6:53 ` Taehee Yoo
2019-09-28 19:20 ` [PATCH net v4 00/12] net: fix nested device bugs Johannes Berg
2019-09-29 8:31 ` Taehee Yoo
2019-10-01 7:39 ` Johannes Berg [this message]
2019-10-05 9:40 ` Taehee Yoo
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