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    SubjectRe: [PATCH -mm] PM: Prevent frozen user mode helpers from failing the freezing of tasks (rev. 2)
    Date
    On Tuesday, 3 July 2007 07:30, Benjamin Herrenschmidt wrote:
    > On Tue, 2007-06-26 at 00:27 +0200, Rafael J. Wysocki wrote:
    > > > > case PM_HIBERNATION_PREPARE:
    > > > > case PM_SUSPEND_PREPARE:
    > > > > usermodehelper_disabled = 1;
    > > > > - return NOTIFY_OK;
    > > > > + smp_mb();
    > > >
    > > > usermodehelper_disabled should be atomic variable, too, so we don't
    > > > have to play these ugly tricks by hand? This should not be
    > > > performance-critical, right?
    > >
    > > Well, I think we'd need to add the barriers anyway.
    > >
    > > The problem, as far as I understand it, is that the instructions can
    > > get
    > > reordered if there are no barriers in there.
    >
    > That seems dodgy either way to me :-)
    >
    > Just use a spinlock.

    Around wait_for_completion()? I don't think that's a good idea. :-)

    Greetings,
    Rafael


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