On Mon, Nov 29, 2021 at 10:26:11AM +0100, Thomas Gleixner wrote: > Jason, > > On Sun, Nov 28 2021 at 20:22, Thomas Gleixner wrote: > > On Sat, Nov 27 2021 at 21:00, Jason Gunthorpe wrote: > >> On Sat, Nov 27, 2021 at 02:22:33AM +0100, Thomas Gleixner wrote: > >> I understand why that isn't desirable at this patch where the storage > >> would have to be a list_head pointer, but still, seems like an odd > >> place to end up at the end of the series. > >> > >> eg add index here unused and then the last patch uses it instead of > >> __iter_idx. > > > > TBH, didn't think about doing just that. OTH, given the experience of > > looking at the creative mess people create, this was probably also a > > vain attempt to make it harder in the future. > > > >> Also, I don't understand why filter was stored in the dev and not > >> passed into msi_next_desc() in the macro here? > > > > No real reason. I probably just stored it along with the rest. Lemme try > > that index approach. > > After looking at all the call sites again, there is no real usage for > this local index variable. > > If anything needs the index of a descriptor then it's available in the > descriptor itself. That won't change because the low level message write > code needs the index too and the only accessible storage there is > msi_desc. Oh, that makes it simpler, just use the current desc->index as the input to the xa_for_each_start() and then there should be no need of hidden state? > What for? The usage sites should not have to care about the storage > details of a facility they are using. Generally for_each things shouldn't have hidden state that prevents them from being nested. It is just an unexpected design pattern.. Jason
