[PATCH v6 02/25] iommu/ioasid: Add ioasid references

[Jean-Philippe Brucker]

On Thu, Apr 30, 2020 at 01:48:42PM -0700, Jacob Pan wrote:
> On Thu, 30 Apr 2020 11:39:31 -0700
> Jacob Pan <jacob.jun.pan at linux.intel.com> wrote:
> 
> > > -void ioasid_free(ioasid_t ioasid)
> > > +bool ioasid_free(ioasid_t ioasid)
> > >  {
> Sorry I missed this in the last reply.
> 
> I think free needs to be unconditional since there is not a good way to
> fail it.
> 
> Also can we have more symmetric APIs, seems we don't have ioasid_put()
> in this patchset.

Yes I was thinking of renaming ioasid_free() to ioasid_put() but got lazy. 

> How about?
> ioasid_alloc()
> ioasid_free(); //drop reference, mark inactive, but not reclaimed if
> 		refcount is not zero.
> ioasid_get() // returns err if the ioasid is marked inactive by
> 		ioasid_free()

How does the caller know that the ioasid is in active/inactive state, and
not freed/reallocated?

> ioasid_put();// drop reference, reclaim if refcount is 0.

I'll add ioasid_put() for now. I'd like to avoid introducing the inactive
state in this patch, so shall I change the calls in the Intel driver to
ioasid_put(), and not introduce a new ioasid_free() for the moment?

Thanks,
Jean