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    SubjectRe: [patch] eventfd - revised interface and cleanups (2nd rev)
    On Tue, 23 Jun 2009, Andrew Morton wrote:

    > On Tue, 23 Jun 2009 12:25:36 -0700 (PDT)
    > Davide Libenzi <> 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
    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

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      Last update: 2009-06-23 21:57    [W:0.024 / U:13.612 seconds]
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