From: Stephen Hemminger <shemminger@vyatta.com>
To: Kalle Valo <kvalo@adurom.com>
Cc: netdev@vger.kernel.org, linux-wireless@vger.kernel.org
Subject: Re: A race in register_netdevice()
Date: Tue, 3 May 2011 16:41:59 -0700 [thread overview]
Message-ID: <20110503164159.6664fa48@nehalam> (raw)
In-Reply-To: <878vungyq4.fsf@purkki.adurom.net>
On Wed, 04 May 2011 02:18:11 +0300
Kalle Valo <kvalo@adurom.com> wrote:
> Hi Stephen,
>
> Stephen Hemminger <shemminger@vyatta.com> writes:
>
> > On Fri, 29 Apr 2011 01:36:37 +0300
> > Kalle Valo <kvalo@adurom.com> wrote:
> >
> >> there seems to be a race in register_netdevice(), which is reported here:
> >>
> >> https://bugzilla.kernel.org/show_bug.cgi?id=15606
> >>
> >> This is visible at least with flimflam and ath6kl. Basically what
> >> happens is this:
> >>
> >> Apr 29 00:21:35 roska flimflamd[2598]: src/udev.c:add_net_device()
> >> Apr 29 00:21:35 roska flimflamd[2598]: connman_inet_ifname: SIOCGIFNAME(index
> >> 4): No such device
> >> Apr 29 00:21:45 roska flimflamd[2598]: src/rtnl.c:rtnl_message() buf
> >> 0xbfefda3c len 1004
> >> Apr 29 00:21:45 roska flimflamd[2598]: src/rtnl.c:rtnl_message()
> >> NEWLINK len 1004 type 16 flags 0x0000 seq 0
>
> [...]
>
> >> I have confirmed that both of these patches fix the issue. Now I'm
> >> wondering which one is the best way forward. Or is there a better way
> >> to fix this?
> >>
> >
> > I see no problem with moving this.
> > SIOCGIFNAME should not need to hold rtnl.
>
> I'm having difficulties of fixing the race and exploring other
> options. Is there any particular issue why SIOCGIFNAME should not take
> rtnl?
None really, but the answer given by SIOCGIFNAME is going to race
anyway. I.e if ioctl returns a value, by the time user space sees it
the result may have changed.
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Hemminger <shemminger-ZtmgI6mnKB3QT0dZR+AlfA@public.gmane.org>
To: Kalle Valo <kvalo-BkwN83ws05HQT0dZR+AlfA@public.gmane.org>
Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: A race in register_netdevice()
Date: Tue, 3 May 2011 16:41:59 -0700 [thread overview]
Message-ID: <20110503164159.6664fa48@nehalam> (raw)
In-Reply-To: <878vungyq4.fsf-5ukZ45wKbUHoml4zekdYB16hYfS7NtTn@public.gmane.org>
On Wed, 04 May 2011 02:18:11 +0300
Kalle Valo <kvalo-BkwN83ws05HQT0dZR+AlfA@public.gmane.org> wrote:
> Hi Stephen,
>
> Stephen Hemminger <shemminger-ZtmgI6mnKB3QT0dZR+AlfA@public.gmane.org> writes:
>
> > On Fri, 29 Apr 2011 01:36:37 +0300
> > Kalle Valo <kvalo-BkwN83ws05HQT0dZR+AlfA@public.gmane.org> wrote:
> >
> >> there seems to be a race in register_netdevice(), which is reported here:
> >>
> >> https://bugzilla.kernel.org/show_bug.cgi?id=15606
> >>
> >> This is visible at least with flimflam and ath6kl. Basically what
> >> happens is this:
> >>
> >> Apr 29 00:21:35 roska flimflamd[2598]: src/udev.c:add_net_device()
> >> Apr 29 00:21:35 roska flimflamd[2598]: connman_inet_ifname: SIOCGIFNAME(index
> >> 4): No such device
> >> Apr 29 00:21:45 roska flimflamd[2598]: src/rtnl.c:rtnl_message() buf
> >> 0xbfefda3c len 1004
> >> Apr 29 00:21:45 roska flimflamd[2598]: src/rtnl.c:rtnl_message()
> >> NEWLINK len 1004 type 16 flags 0x0000 seq 0
>
> [...]
>
> >> I have confirmed that both of these patches fix the issue. Now I'm
> >> wondering which one is the best way forward. Or is there a better way
> >> to fix this?
> >>
> >
> > I see no problem with moving this.
> > SIOCGIFNAME should not need to hold rtnl.
>
> I'm having difficulties of fixing the race and exploring other
> options. Is there any particular issue why SIOCGIFNAME should not take
> rtnl?
None really, but the answer given by SIOCGIFNAME is going to race
anyway. I.e if ioctl returns a value, by the time user space sees it
the result may have changed.
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2011-05-03 23:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-28 22:36 A race in register_netdevice() Kalle Valo
2011-04-28 22:36 ` Kalle Valo
2011-04-28 23:52 ` Stephen Hemminger
2011-04-28 23:52 ` Stephen Hemminger
2011-04-29 17:20 ` Kalle Valo
2011-05-03 23:18 ` Kalle Valo
2011-05-03 23:41 ` Stephen Hemminger [this message]
2011-05-03 23:41 ` Stephen Hemminger
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110503164159.6664fa48@nehalam \
--to=shemminger@vyatta.com \
--cc=kvalo@adurom.com \
--cc=linux-wireless@vger.kernel.org \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.