Re: [EXT] Re: [PATCH v7 rdma-next 2/7] RDMA/core: Create mmap database and cookie helper functions

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, Aug 21, 2019 at 05:14:38PM +0000, Michal Kalderon wrote:

> > > Jason, I looked into this deeper today, it seems that since the Core
> > > is the one handling the reference counting, and eventually Freeing the
> > > object that it makes more sense to keep the allocation In core and not
> > > in the drivers, since the driver won't be able to free The entry
> > > without providing yet an additional callback function to the Core to
> > > be called once the reference count reaches zero.
> > 
> > This already added a callback to free the xa_entry, why can't it free all the
> > memory too when kref goes to 0?
> True, could free it there. I just think we'll have a bit more
> duplication code

Well, the drivers already needed to allocate something right?

> Between the drivers defining a very similar private structure and adding
> Allocation calls before each of the rdma_user_mmap_insert function calls. 
>  And just to make sure I follow, 
> Do you mean creating the following structure per driver: 
> Struct <driver>_user_mmap_entry {
> 	struct rdma_user_mmap_entry umap_entry;
>               ... <private fields> ...
> }

Yes, that is the general pattern

Jaosn