On Tue, 23 Jun 2009, Andrew Morton wrote: > On Tue, 23 Jun 2009 12:25:36 -0700 (PDT) > Davide Libenzi <davidel@xxxxxxxxxxxxxxx> wrote: > > > The following patch changes the eventfd interface to de-couple the eventfd > > memory context, from the file pointer instance. > > Without such change, there is no clean way to racely free handle the > > POLLHUP event sent when the last instance of the file* goes away. > > Also, now the internal eventfd APIs are using the eventfd context instead > > of the file*. > > Another cleanup this patch does, is making AIO select EVENTFD, instead of > > adding a bunch of empty function stubs inside eventfd.h in order to > > handle the (AIO && !EVENTFD) case. > > > > If we really want to squeeze this into 2.6.31 then it would be helpful > to have justification in the changelog, please. I see that some KVM > feature needs it, but what and why and why now, etc? The patch in -next added the ability to have waiters to be notified when the last instance of the file* is dropped (that is, on ->release). But it is not possible for waiters to handle the POLLHUP event in a racy-free way, unless the eventfd memory context is de-coupled from the file*. The next patches from gregory will use eventfd (and the POLLHUP handling) to implement the IRQfd code inside KVM. > What's going on here? The POLLHUP patch in -next is not sufficent. I based the patch over mainline, but if you guys want I can rebase it over -next. - Davide -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
