netdev - Re: [PATCH net] selftests/net: set link down before enslave

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Message-ID: <20210120174644.083de7fa@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Wed, 20 Jan 2021 17:46:51 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Ido Schimmel <idosch@...sch.org>
Cc:     Hangbin Liu <liuhangbin@...il.com>,
        Ido Schimmel <idosch@...dia.com>, netdev@...r.kernel.org,
        Jiri Pirko <jiri@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] selftests/net: set link down before enslave

On Wed, 20 Jan 2021 21:43:28 +0200 Ido Schimmel wrote:
> On Wed, Jan 20, 2021 at 10:38:47PM +0800, Hangbin Liu wrote:
> > Hi Ido,
> > 
> > On Wed, Jan 20, 2021 at 12:42:10PM +0200, Ido Schimmel wrote:  
> > > > diff --git a/tools/testing/selftests/net/rtnetlink.sh b/tools/testing/selftests/net/rtnetlink.sh
> > > > index c9ce3dfa42ee..a26fddc63992 100755
> > > > --- a/tools/testing/selftests/net/rtnetlink.sh
> > > > +++ b/tools/testing/selftests/net/rtnetlink.sh
> > > > @@ -1205,6 +1205,8 @@ kci_test_bridge_parent_id()
> > > >  	dev20=`ls ${sysfsnet}20/net/`
> > > >  
> > > >  	ip link add name test-bond0 type bond mode 802.3ad
> > > > +	ip link set dev $dev10 down
> > > > +	ip link set dev $dev20 down  
> > > 
> > > But these netdevs are created with their administrative state set to
> > > 'DOWN'. Who is setting them to up?  
> > 
> > Would you please point me where we set the state to 'DOWN'? Cause on my
> > host it is init as UP:
> > 
> > ++ ls /sys/bus/netdevsim/devices/netdevsim10/net/
> > + dev10=eth3
> > ++ ls /sys/bus/netdevsim/devices/netdevsim20/net/
> > + dev20=eth4
> > + ip link add name test-bond0 type bond mode 802.3ad
> > + ip link show eth3
> > 66: eth3: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
> >     link/ether 1e:52:27:5f:a5:3c brd ff:ff:ff:ff:ff:ff  
> 
> I didn't have time to look into this today, but I suspect the problem is
> either:
> 
> 1. Some interface manager on your end that is setting these interfaces
> up after they are created

This must be the case, the kernel doesn't open/up devices by itself.

> 2. A bug in netdevsim that does not initialize the carrier to off.
> Maybe try with this patch (didn't test):

Yeah, but that's fine, SW devices don't have to manage carrier state.