On Mon, 2013-10-07 at 14:01 -0400, Tejun Heo wrote: > I don't think the same race condition would happen with the loop. The > problem case is where multiple msi(x) allocation fails completely > because the global limit went down before inquiry and allocation. In > the loop based interface, it'd retry with the lower number. > > As long as the number of drivers which need this sort of adaptive > allocation isn't too high and the common cases can be made simple, I > don't think the "complex" part of interface is all that important. > Maybe we can have reserve / cancel type interface or just keep the > loop with more explicit function names (ie. try_enable or something > like that). I'm thinking a better API overall might just have been to request individual MSI-X one by one :-) We want to be able to request an MSI-X at runtime anyway ... if I want to dynamically add a queue to my network interface, I want it to be able to pop a new arbitrary MSI-X. And we don't want to lock drivers into contiguous MSI-X sets either. And for the cleanup ... well that's what the "pcim" functions are for, we can just make MSI-X variants. Ben.
