On Mon, Sep 07, 2020 at 05:28:23PM +0800, Ka-Cheong Poon wrote:
> On 9/7/20 5:04 PM, Leon Romanovsky wrote:
> > On Mon, Sep 07, 2020 at 04:24:26PM +0800, Ka-Cheong Poon wrote:
> > > On 9/7/20 3:18 PM, Leon Romanovsky wrote:
> > > > On Mon, Sep 07, 2020 at 11:33:38AM +0800, Ka-Cheong Poon wrote:
> > > > > On 9/6/20 3:44 PM, Leon Romanovsky wrote:
> > > > > > On Fri, Sep 04, 2020 at 10:02:10PM +0800, Ka-Cheong Poon wrote:
> > > > > > > On 9/4/20 7:32 PM, Jason Gunthorpe wrote:
> > > > > > > > On Fri, Sep 04, 2020 at 12:01:12PM +0800, Ka-Cheong Poon wrote:
> > > > > > > > > On 9/4/20 1:39 AM, Jason Gunthorpe wrote:
> > > > > > > > > > On Thu, Sep 03, 2020 at 10:02:01PM +0800, Ka-Cheong Poon wrote:
> > > > > > > > > > > When a struct ib_client's add() function is called. is there a
> > > > > > > > > > > supported method to find out the namespace of the passed in
> > > > > > > > > > > struct ib_device? There is rdma_dev_access_netns() but it does
> > > > > > > > > > > not return the namespace. It seems that it needs to have
> > > > > > > > > > > something like the following.
> > > > > > > > > > >
> > > > > > > > > > > struct net *rdma_dev_to_netns(struct ib_device *ib_dev)
> > > > > > > > > > > {
> > > > > > > > > > > return read_pnet(&ib_dev->coredev.rdma_net);
> > > > > > > > > > > }
> > > > > > > > > > >
> > > > > > > > > > > Comments?
> > > > > > > > > >
> > > > > > > > > > I suppose, but why would something need this?
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > If the client needs to allocate stuff for the namespace
> > > > > > > > > related to that device, it needs to know the namespace of
> > > > > > > > > that device. Then when that namespace is deleted, the
> > > > > > > > > client can clean up those related stuff as the client's
> > > > > > > > > namespace exit function can be called before the remove()
> > > > > > > > > function is triggered in rdma_dev_exit_net(). Without
> > > > > > > > > knowing the namespace of that device, coordination cannot
> > > > > > > > > be done.
> > > > > > > >
> > > > > > > > Since each device can only be in one namespace, why would a client
> > > > > > > > ever need to allocate at a level more granular than a device?
> > > > > > >
> > > > > > >
> > > > > > > A client wants to have namespace specific info. If the
> > > > > > > device belongs to a namespace, it wants to associate those
> > > > > > > info with that device. When a namespace is deleted, the
> > > > > > > info will need to be deleted. You can consider the info
> > > > > > > as associated with both a namespace and a device.
> > > > > >
> > > > > > Can you be more specific about which info you are talking about?
> > > > >
> > > > >
> > > > > Actually, a lot of info can be both namespace and device specific.
> > > > > For example, a client wants to have a different PD allocation policy
> > > > > with a device when used in different namespaces.
> > > > >
> > > > >
> > > > > > And what is the client that is net namespace-aware from one side,
> > > > > > but from another separate data between them "manually"?
> > > > >
> > > > >
> > > > > Could you please elaborate what is meant by "namespace aware from
> > > > > one side but from another separate data between them manually"?
> > > > > I understand what namespace aware means. But it is not clear what
> > > > > is meant by "separating data manually". Do you mean having different
> > > > > behavior in different namespaces? If this is the case, there is
> > > > > nothing special here. An admin may choose to have different behavior
> > > > > in different namespaces. There is nothing manual going on in the
> > > > > client code.
> > > >
> > > > We are talking about net-namespaces, and as we wrote above, the ib_device
> > > > that supports such namespace can exist only in a single one
> > > >
> > > > The client that implemented such support can check its namespace while
> > > > "client->add" is called. It should be equal to be seen by ib_device.
> > > >
> > > > See:
> > > > rdma_dev_change_netns ->
> > > > enable_device_and_get ->
> > > > add_client_context ->
> > > > client->add(device)
> > >
> > >
> > > This is the original question. How does the client's add() function
> > > know the namespace of device? What is your suggestion in finding
> > > the net namespace of device at add() time?
> >
> > As I wrote above, "It should be equal to be seen by ib_device.", check net
> > namespace of your client.
>
>
> Could you please be more specific? A client calls ib_register_client() to
> register with the RDMA framework. Then when a device is added, the client's
> add() function is called with the struct ib_device. How does the client
> find out the namespace "seen by the ib_device"? Do you mean that there is
> a variant of ib_register_client() which can take a net namespace as parameter?
> Or is there a variant of struct ib_client which has a net namespace field?
> Or? Thanks.
"Do you mean that there is a variant of ib_register_client()
which can take a net namespace as parameter?"
No, it doesn't exist but it is easy to extend and IMHO the right
thing to do.
Thanks
