Re: [PATCH 02/11] IB/ipoib: Return IPoIB devices matching connection parameters

Haggai Eran
2015-06-16T06:36:35Z

On 15/06/2015 20:22, Jason Gunthorpe wrote:
> On Mon, Jun 15, 2015 at 11:47:07AM +0300, Haggai Eran wrote:
>
>> +/* Called with an RCU read lock taken */
>
> Add _rcu to the name? That is the standard convention.

Sure, I'll change that.

>
>> +/* returns an IPoIB netdev on top a given ipoib device matching a pkey_index
>> + * and address, if one exists. */
>> +static struct net_device *ipoib_match_gid_pkey_addr(struct ipoib_dev_priv *priv,
>> + const union ib_gid *gid,
>> + u16 pkey_index,
>> + const struct sockaddr *addr)
>> +{
>> + struct ipoib_dev_priv *child_priv;
>> + struct net_device *net_dev = NULL;
>> +
>> + if (priv->pkey_index == pkey_index &&
>> + (!gid || !memcmp(gid, &priv->local_gid, sizeof(*gid)))) {
>> + net_dev = ipoib_get_net_dev_match_addr(addr, priv->dev);
>> + if (net_dev)
>> + return net_dev;
>
> As I said already, this should not even look at the sockaddr unless
> there are multiple possible hits on the other parameters,
What is the goal here? The only difference omitting the IP check will
make is when sending a request to a matching GID but with the wrong IP.
Is it important that we pass these requests here so that they will be
dropped at the rdma_cm module?

Also, note that ipoib_get_net_dev_match_addr can return a different
net_dev from the one ipoib created. When using bonding, it will find the
IP address on the bonding device, and return the bonding net_dev instead.

> and there
> should be a comment explaining the sockaddr is only a hack to make up
> for having an incomplete LLADDR.

Sure, I'll add a comment.

>
> That way people not using same guid children do not get incorrect
> functionality..
>
>> +static struct net_device *ipoib_get_net_dev_by_params(
>> + struct ib_device *dev, u8 port, u16 pkey,
>> + const union ib_gid *gid, const struct sockaddr *addr)
>
> [..]
>
>> + ret = ib_find_cached_pkey(dev, port, pkey, &pkey_index);
>> + if (ret)
>> + return NULL;
>> +
>> + if (!rdma_protocol_ib(dev, port))
>> + return NULL;
>
> This if should be first I'd think.

Okay.

>
>
>> + dev_list = ib_get_client_data(dev, &ipoib_client);
>> + if (!dev_list)
>> + return NULL;
>
> Is the locking OK here? This access protected by lists_rwsem -
> but for instance ib_unregister_device holds only the device_mutex when
> calling client->remove, which kfree's dev_list. Looks wrong to me.

I think you're right. Perhaps we can switch the client data to NULL in
ib_unregister_device under the lists_rwsem. Then the
ipoib_get_net_dev_by_params call will know to skip it. The remove()
callback will need to be augmented with the client data as a parameter,
because it won't be able to retrieve it using ib_get_client_data anymore.

Haggai