-----"Jason Gunthorpe" <jgg@xxxxxxxx> wrote: -----
>To: "Bernard Metzler" <BMT@xxxxxxxxxxxxxx>
>From: "Jason Gunthorpe" <jgg@xxxxxxxx>
>Date: 03/06/2019 08:43PM
>Cc: "Gal Pressman" <galpress@xxxxxxxxxx>, linux-rdma@xxxxxxxxxxxxxxx
>Subject: Re: [PATCH v5 06/13] SIW application interface
>
>On Thu, Feb 28, 2019 at 03:38:55PM +0000, Bernard Metzler wrote:
>
>> >> +int siw_mmap(struct ib_ucontext *ctx, struct vm_area_struct
>*vma)
>> >> +{
>> >> + struct siw_ucontext *uctx = to_siw_ctx(ctx);
>> >> + struct siw_uobj *uobj;
>> >> + u32 key = vma->vm_pgoff << PAGE_SHIFT;
>> >> + int size = vma->vm_end - vma->vm_start;
>> >> + int rv = -EINVAL;
>> >> +
>> >> + /*
>> >> + * Must be page aligned
>> >> + */
>> >> + if (vma->vm_start & (PAGE_SIZE - 1)) {
>> >> + pr_warn("map not page aligned\n");
>> >> + goto out;
>> >> + }
>> >> +
>> >> + uobj = siw_remove_uobj(uctx, key, size);
>> >> + if (!uobj) {
>> >> + pr_warn("mmap lookup failed: %u, %d\n", key, size);
>> >> + goto out;
>> >> + }
>> >
>> >EFA used to remove the objects from the list on mmap and we were
>> >asked by Jason
>> >to keep them in the list until dealloc_ucontext. This way multiple
>> >mmaps could
>> >work as well.
>>
>> siw user land library currently does not support multiple mappings
>of
>> the same object, will consider in the future.
>
>We should have sane semantics for mmap and related - don't discard
>the
>offset once it is exposed unless really necessary.
>
>And this thing with search a list is not great, use a cyclic xarray
>to
>generate and find the unique offset cookies.
>
I had it a list since I kept the list short ;)
