netdev - Re: [PATCH net-next v2 1/1] bridge: return error code when deleting Vlan

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Date:   Thu, 12 Oct 2017 14:07:20 -0400
From:   Roman Mashak <mrv@...atatu.com>
To:     David Ahern <dsahern@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v2 1/1] bridge: return error code when deleting Vlan

On Thu, Oct 12, 2017 at 10:19 AM, David Ahern <dsahern@...il.com> wrote:
> On 10/12/17 7:51 AM, Roman Mashak wrote:
>> v2:
>>  Return err immediately if nbp_vlan_delete() fails (pointed by David Ahern)
>>
>> Signed-off-by: Roman Mashak <mrv@...atatu.com>
>> ---
>>  net/bridge/br_netlink.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>> index f0e8268..1efdd48 100644
>> --- a/net/bridge/br_netlink.c
>> +++ b/net/bridge/br_netlink.c
>> @@ -527,11 +527,13 @@ static int br_vlan_info(struct net_bridge *br, struct net_bridge_port *p,
>>
>>       case RTM_DELLINK:
>>               if (p) {
>> -                     nbp_vlan_delete(p, vinfo->vid);
>> +                     err = nbp_vlan_delete(p, vinfo->vid);
>> +                     if (err)
>> +                             break;
>
> I'm not sure a break is the right thing to do. Seems like you leave it
> in a half configured state.
>
>>                       if (vinfo->flags & BRIDGE_VLAN_INFO_MASTER)
>> -                             br_vlan_delete(p->br, vinfo->vid);
>> +                             err = br_vlan_delete(p->br, vinfo->vid);
>>               } else {
>> -                     br_vlan_delete(br, vinfo->vid);
>> +                     err = br_vlan_delete(br, vinfo->vid);
>>               }
>>               break;
>>       }
>>
>
> Why do you want to return the error code here? Walking the code paths
> seems like ENOENT or err from switchdev_port_obj_del are the 2 error
> possibilities.

For example, if you attempt to delete a non-existing vlan on a port,
the current code succeeds and also sends event :

rtnetlink_rcv_msg
    rtnl_bridge_dellink
       br_dellink
          br_afspec
             br_vlan_info

int br_dellink(..)
{
  ...
  err = br_afspec()
  if (err == 0)
      br_ifinfo_notify(RTM_NEWLINK, p);
}

This is misleading, so a proper errcode has to be produced.