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.
prev parent reply other threads:[~2011-05-03 23:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-28 22:36 A race in register_netdevice() Kalle Valo
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]
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