netdev - Re: [RFC] rtnetlink: handle multiple vlan tags in set_vf

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Date:   Fri, 22 Feb 2019 10:09:53 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Moshe Shemesh <moshe@...lanox.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>
Subject: Re: [RFC] rtnetlink: handle multiple vlan tags in set_vf_vlan

On Fri, 22 Feb 2019 04:58:06 +0000
Moshe Shemesh <moshe@...lanox.com> wrote:

> On 2/21/2019 7:54 PM, Stephen Hemminger wrote:
> > The netlink API for IFLA_VF_VLAN_LIST allows multiple VLAN tags to
> > be passed (and the message was validated) but only the first VLAN
> > tag was being passed to the device. Change to iterate over each tag received.
> > 
> > Fixes: 79aab093a0b5 ("net: Update API for VF vlan protocol 802.1ad support")
> > Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
> > ---
> >   net/core/rtnetlink.c | 19 ++++++++++---------
> >   1 file changed, 10 insertions(+), 9 deletions(-)
> > 
> > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> > index a51cab95ba64..3a9ec988ae21 100644
> > --- a/net/core/rtnetlink.c
> > +++ b/net/core/rtnetlink.c
> > @@ -2207,11 +2207,10 @@ static int do_setvfinfo(struct net_device *dev, struct nlattr **tb)
> >   	if (tb[IFLA_VF_VLAN_LIST]) {
> >   		struct ifla_vf_vlan_info *ivvl[MAX_VLAN_LIST_LEN];
> >   		struct nlattr *attr;
> > -		int rem, len = 0;
> > +		int i, rem, len = 0;
> >   
> > -		err = -EOPNOTSUPP;
> >   		if (!ops->ndo_set_vf_vlan)
> > -			return err;
> > +			return -EOPNOTSUPP;
> >   
> >   		nla_for_each_nested(attr, tb[IFLA_VF_VLAN_LIST], rem) {
> >   			if (nla_type(attr) != IFLA_VF_VLAN_INFO ||
> > @@ -2224,13 +2223,15 @@ static int do_setvfinfo(struct net_device *dev, struct nlattr **tb)
> >   
> >   			len++;
> >   		}
> > -		if (len == 0)
> > -			return -EINVAL;
> >   
> > -		err = ops->ndo_set_vf_vlan(dev, ivvl[0]->vf, ivvl[0]->vlan,
> > -					   ivvl[0]->qos, ivvl[0]->vlan_proto);
> > -		if (err < 0)
> > -			return err;
> > +		err = -EINVAL; /* empty list error */
> > +		for (i = 0; i < len; i++) {
> > +			err = ops->ndo_set_vf_vlan(dev, ivvl[i]->vf,
> > +						   ivvl[i]->vlan, ivvl[i]->qos,
> > +						   ivvl[i]->vlan_proto);  
> 
> Doing that each vlan will just overwrite the vf vlan configuration set 
> by its preceding one.
> Note #define MAX_VLAN_LIST_LEN 1
> The point here was that I had to add the rtnl interface to set vf vlan 
> with option to set vf vlan protocol. While doing that I was asked to add 
> option to get a list of vlans from user to support QinQ, so once it will 
> be needed there won't be a need to add another rtnl interface.
> 
> The driver which will support setting double vlan or more per vf will 
> change MAX_VLAN_LIST_LEN and change the ndo function.
> 

OK, then the original code kind of makes sense now. Maybe the whole loop
could be eliminated.

I expected that the vlan list was for allowing multiple vlan's to go to
a single VF but it is really a future (unlikely to ever be implemented)
support for QinQ.