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Date: Fri, 02 Nov 2012 15:48:32 -0700
From: John Fastabend <john.r.fastabend@...el.com>
To: Ben Hutchings <bhutchings@...arflare.com>
CC: shemminger@...tta.com, buytenh@...tstofly.org, davem@...emloft.net,
vyasevic@...hat.com, jhs@...atatu.com, chrisw@...hat.com,
krkumar2@...ibm.com, samudrala@...ibm.com,
peter.p.waskiewicz.jr@...el.com, jeffrey.t.kirsher@...el.com,
netdev@...r.kernel.org, gregory.v.rose@...el.com,
eilong@...adcom.com
Subject: Re: [net-next PATCH v2 2/3] net: set and query VEB/VEPA bridge mode
via PF_BRIDGE
On 11/2/2012 3:38 PM, Ben Hutchings wrote:
> On Wed, 2012-10-24 at 11:13 -0700, John Fastabend wrote:
>> Hardware switches may support enabling and disabling the
>> loopback switch which puts the device in a VEPA mode defined
>> in the IEEE 802.1Qbg specification. In this mode frames are
>> not switched in the hardware but sent directly to the switch.
>> SR-IOV capable NICs will likely support this mode I am
>> aware of at least two such devices. Also I am told (but don't
>> have any of this hardware available) that there are devices
>> that only support VEPA modes. In these cases it is important
>> at a minimum to be able to query these attributes.
>>
>> This patch adds an additional IFLA_BRIDGE_MODE attribute that can be
>> set and dumped via the PF_BRIDGE:{SET|GET}LINK operations. Also
>> anticipating bridge attributes that may be common for both embedded
>> bridges and software bridges this adds a flags attribute
>> IFLA_BRIDGE_FLAGS currently used to determine if the command or event
>> is being generated to/from an embedded bridge or software bridge.
>> Finally, the event generation is pulled out of the bridge module and
>> into rtnetlink proper.
> [...]
>> --- a/net/core/rtnetlink.c
>> +++ b/net/core/rtnetlink.c
> [...]
>> +static int rtnl_bridge_notify(struct net_device *dev, u16 flags)
>> +{
>> + struct net *net = dev_net(dev);
>> + struct net_device *master = dev->master;
>> + struct sk_buff *skb;
>> + int err = -EOPNOTSUPP;
>> +
>> + skb = nlmsg_new(bridge_nlmsg_size(), GFP_ATOMIC);
>> + if (!skb) {
>> + err = -ENOMEM;
>> + goto errout;
>> + }
>> +
>> + if (!flags && master && master->netdev_ops->ndo_bridge_getlink)
>> + err = master->netdev_ops->ndo_bridge_getlink(skb, 0, 0, dev);
>> + else if (dev->netdev_ops->ndo_bridge_getlink)
>> + err = dev->netdev_ops->ndo_bridge_getlink(skb, 0, 0, dev);
>
> This doesn't make sense. If flags == BRIDGE_FLAGS_MASTER then we only
> send the 'self' information. If flags == BRIDGE_FLAGS_MASTER |
> BRIDGE_FLAGS_SELF then we only send the master information.
>
agh. I screwed this up when I made this handle setting both master
and self flags. I'll fix it. Thanks.
> [...]
>> static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
>> void *arg)
>> {
>> struct net *net = sock_net(skb->sk);
>> struct ifinfomsg *ifm;
>> struct net_device *dev;
>> - int err = -EINVAL;
>> + struct nlattr *br_spec, *attr = NULL;
>> + int rem, err = -EOPNOTSUPP;
>> + u16 flags = 0;
>>
>> if (nlmsg_len(nlh) < sizeof(*ifm))
>> return -EINVAL;
>> @@ -2316,15 +2363,45 @@ static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
>> return -ENODEV;
>> }
>>
>> - if (dev->master && dev->master->netdev_ops->ndo_bridge_setlink) {
>> + br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
>> + if (br_spec) {
>> + nla_for_each_nested(attr, br_spec, rem) {
>> + if (nla_type(attr) == IFLA_BRIDGE_FLAGS) {
>> + flags = nla_get_u16(attr);
>> + break;
>> + }
>> + }
>> + }
>> +
>> + if (!flags || (flags & BRIDGE_FLAGS_MASTER)) {
>> + if (!dev->master ||
>> + !dev->master->netdev_ops->ndo_bridge_setlink) {
>> + err = -EOPNOTSUPP;
>> + goto out;
>> + }
>> +
>> err = dev->master->netdev_ops->ndo_bridge_setlink(dev, nlh);
>> if (err)
>> goto out;
>> +
>> + flags &= ~BRIDGE_FLAGS_MASTER;
>> }
>>
>> - if (dev->netdev_ops->ndo_bridge_setlink)
>> - err = dev->netdev_ops->ndo_bridge_setlink(dev, nlh);
>> + if ((flags & BRIDGE_FLAGS_SELF)) {
>> + if (!dev->netdev_ops->ndo_bridge_setlink)
>> + err = -EOPNOTSUPP;
>> + else
>> + err = dev->netdev_ops->ndo_bridge_setlink(dev, nlh);
>> +
>> + if (!err)
>> + flags &= ~BRIDGE_FLAGS_SELF;
>> + }
>>
>> + if (attr && nla_type(attr) == IFLA_BRIDGE_FLAGS)
>
> This condition is wrong; attr will *not* be NULL if the
> nla_for_each_nested() loop terminates without finding an
> IFLA_BRIDGE_FLAGS attribute.
It might be NULL if the nlmsg has no IFLA_AF_SPEC attr. In this case
we still need to send the PROTINFO attribute to the master which
could be the linux bridge.
>
>> + memcpy(nla_data(attr), &flags, sizeof(flags));
>> + /* Generate event to notify upper layer of bridge change */
>> + if (!err)
>> + err = rtnl_bridge_notify(dev, flags);
>
> flags has been modified above; surely we want to use the original value
> here?
Yes. Thanks Ben. I'll have a patch shortly.
>
> Ben.
>
>> out:
>> return err;
>> }
>>
>
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