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Re: Possible race with br_del_if()

To: Ryan Harper <ryanh@xxxxxxxxxx>
Subject: Re: Possible race with br_del_if()
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Thu, 18 Aug 2005 15:35:31 -0700
Cc: netdev@xxxxxxxxxxx
In-reply-to: <20050818222323.GI10593@xxxxxxxxxx>
References: <20050818214036.GH10593@xxxxxxxxxx> <20050818151202.6fe6ded4@xxxxxxxxxxxxxxxxx> <20050818222323.GI10593@xxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
On Thu, 18 Aug 2005 17:23:23 -0500
Ryan Harper <ryanh@xxxxxxxxxx> wrote:

> * Stephen Hemminger <shemminger@xxxxxxxx> [2005-08-18 17:11]:
> > On Thu, 18 Aug 2005 16:40:36 -0500
> > Ryan Harper <ryanh@xxxxxxxxxx> wrote:
> > 
> > > Hello,
> > > 
> > > I've encountered several oops when adding and removing interfaces from
> > > bridges while using Xen.  Most of the details are available [1]here.
> > > The short of it is the following sequence:
> > 
> > Doesn't the mutex in RTNL work right?  or are you calling
> > routines with out asserting it?
> 
> unregister_netdevice asserts RTNL, add_del_if() in br_ioctl.c doesn't
> seem to do so.  I don't see it down dev_get_by_index() path either.  It
> looks like any caller of add_del_if() isn't asserting RTNL.  The two
> callers I see are:
> 
> br_dev_ioctl() in br_ioctl.c
> old_dev_ioctl() in br_ioctl.c

But the pat to br_dev_ioctl() is via the socket ioctl and that
should already have gotten RTNL.


dev_ioctl
        rtnl_lock()
        dev_ifsioc()
                dev->do_ioctl --> br_dev_ioctl

                        

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