Re: Finding the namespace of a struct ib_device

[Ka-Cheong Poon <ka-cheong.poon@oracle.com>]

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.


-- 
K. Poon
ka-cheong.poon@oracle.com