Davide Libenzi wrote: > On Mon, 22 Jun 2009, Michael S. Tsirkin wrote: > > >> On Mon, Jun 22, 2009 at 11:03:22AM -0700, Davide Libenzi wrote: >> >>> In your case of kernel-to-kernel scenario, why would you need eventfd at >>> all, if userspace role in that model is simply to create it? >>> >> That's not 100% true. We have a mode where userspace is the producer >> and/or consumer (migration mode) and we switch between that and >> direct kernel-to-kernel communication. >> > > Then you'd need to ask yourself how to handle your complex case inside the > KVM code, so that other eventfd users are not affected by the extra fat > needed to handle your scenarios. Thing that seem to be continuosly tried. > A file* based kernel-to-kernel interface is rather wrong IMO. > Well, I will point out that the interface in question is eventfd_signal(struct file *), and you were the one that invented it afaict. Can't help it if we like it :) BTW: The termination point of that call is incidental. Afterall, it works the same for kernel-kernel or kernel-userspace. The only relevant discussion point here is that your proposal breaks POLLHUP for eventfd_signal() users, and we have a real use case that cares. Let me ask the question a different way: Lets say we all agree that eventfd_signal() cannot be file* based to be correct. Is there a way you can think of that satisfies both the need to get rid of file* AND still deliver producer-release notification to consumers. Ultimately that is all I care about. -Greg
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