7:48 a.m.
On Mon, Aug 12, 2019 at 09:28:14AM -0300, Jason Gunthorpe wrote:
On Fri, Aug 09, 2019 at 03:58:29PM -0700, ira.weiny(a)intel.com wrote:
> From: Ira Weiny <ira.weiny(a)intel.com>
>
> The addition of FOLL_LONGTERM has taken on additional meaning for CMA
> pages.
>
> In addition subsystems such as RDMA require new information to be passed
> to the GUP interface to track file owning information. As such a simple
> FOLL_LONGTERM flag is no longer sufficient for these users to pin pages.
>
> Introduce a new GUP like call which takes the newly introduced vaddr_pin
> information. Failure to pass the vaddr_pin object back to a vaddr_put*
> call will result in a failure if pins were created on files during the
> pin operation.
Is this a 'vaddr' in the traditional sense, ie does it work with
something returned by valloc?
...or malloc in user space, yes. I think the idea is that it is a user virtual
address.
Maybe another name would be better?
Maybe, the name I had was way worse... So I'm not even going to admit to it...
;-)
So I'm open to suggestions. Jan gave me this one, so I figured it was safer to
suggest it...
:-D
I also wish GUP like functions took in a 'void __user *' instead of
the unsigned long to make this clear :\
Not a bad idea. But I only see a couple of call sites who actually use a 'void
__user *' to pass into GUP... :-/
For RDMA the address is _never_ a 'void __user *' AFAICS.
For the new API, it may be tractable to force users to cast to 'void __user *'
but it is not going to provide any type safety.
But it is easy to change in this series.
What do others think?
Ira
Jason
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Ira Weiny