RE: [EXT] Re: [PATCH v11 rdma-next 6/7] RDMA/qedr: Add doorbell overflow recovery support

Michal Kalderon
2019-09-23T09:31:05Z

> From: Jason Gunthorpe <jgg@ziepe.ca>
> Sent: Thursday, September 19, 2019 9:02 PM
>
> External Email
>
> ----------------------------------------------------------------------
> On Thu, Sep 05, 2019 at 01:01:16PM +0300, Michal Kalderon wrote:
>
> > @@ -347,6 +360,9 @@ void qedr_mmap_free(struct
> rdma_user_mmap_entry
> > *rdma_entry) {
> > struct qedr_user_mmap_entry *entry =
> > get_qedr_mmap_entry(rdma_entry);
> >
> > + if (entry->mmap_flag == QEDR_USER_MMAP_PHYS_PAGE)
> > + free_page((unsigned long)phys_to_virt(entry->address));
> > +
>
> While it isn't wrong it do it this way, we don't need this mmap_free() stuff for
> normal CPU pages. Those are refcounted and qedr can simply call
> free_page() during the teardown of the uobject that is using the this page.
> This is what other drivers already do.
>
> I'm also not sure why qedr is using a phys_addr for a struct page object,
> seems wrong.
As mentioned in previous email, I misunderstood this part before. I'll move the free
To object teardown.
What we need here is simply a shared page between kernel + user that both have
Virtual pointers to, user writes to the page, kernel needs to read the data.

The reason I used phys here is because the entry->address is defines as u64
As it is common whether it is an address to the bar or a page...
Should I define a union based on the entry type ? and for a page use
struct page object ?

>
> Jason