On 2/11/19 1:26 PM, Ira Weiny wrote: > On Mon, Feb 11, 2019 at 01:13:56PM -0800, John Hubbard wrote: >> On 2/11/19 12:39 PM, Jason Gunthorpe wrote: >>> On Mon, Feb 11, 2019 at 12:16:42PM -0800, ira.weiny@xxxxxxxxx wrote: >>>> From: Ira Weiny <ira.weiny@xxxxxxxxx> >> [...] >> It seems to me that the longterm vs. short-term is of questionable value. > > This is exactly why I did not post this before. I've been waiting our other > discussions on how GUP pins are going to be handled to play out. But with the > netdev thread today[1] it seems like we need to make sure we have a "safe" fast > variant for a while. Introducing FOLL_LONGTERM seemed like the cleanest way to > do that even if we will not need the distinction in the future... :-( Yes, I agree. Below... > [...] > This is also why I did not change the get_user_pages_longterm because we could > be ripping this all out by the end of the year... (I hope. :-) > > So while this does "pollute" the GUP family of calls I'm hoping it is not > forever. > > Ira > > [1] https://lkml.org/lkml/2019/2/11/1789 > Yes, and to be clear, I think your patchset here is fine. It is easy to find the FOLL_LONGTERM callers if and when we want to change anything. I just think also it's appopriate to go a bit further, and use FOLL_LONGTERM all by itself. That's because in either design outcome, it's better that way: -- If we keep the concept of "I'm a long-term gup call site", then FOLL_LONGTERM is just right. The gup API already has _fast and non-fast variants, and once you get past a couple, you end up with a multiplication of names that really work better as flags. We're there. -- If we drop the concept, then you've already done part of the work, by removing the _longterm API variants. thanks, -- John Hubbard NVIDIA
