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    SubjectRe: [PULL] cpumask: finally make them variable size w/ CPUMASK_OFFSTACK.

    * Rusty Russell <> wrote:

    > Hi Ingo,
    > I finally rebased this on top of your tip tree, and tested it
    > locally. Some more old-style cpumask usages have crept in, but it's a
    > fairly simple series.

    Cool! Most of it looks pretty sane. I have a question about the
    gist of the series:

    > commit 898eb73305e2277be91b931c5a75484f8c87ae36
    > Author: Rusty Russell <>
    > Date: Wed May 9 15:01:15 2012 +0930
    > cpumask: remove struct cpumask definition when CONFIG_CPUMASK_OFFSTACK=y
    > We're about to change CONFIG_CPUMASK_OFFSTACK so it only allocate
    > nr_cpu_ids bits for all cpumasks. We need to make sure that when
    > 1) Noone uses the old bitmap ops, which use NR_CPUS bits (use cpumask_*)
    > 2) Noone uses assignment of struct cpumask (use cpumask_copy)
    > 3) Noone passes a struct cpumask (pass a pointer)
    > 4) Noone declares them on the stack (use cpumask_var_t)
    > So we finally remove the definition of struct cpumask when
    > CONFIG_CPUMASK_OFFSTACK=y. This means that these usages will hit a compile
    > error the moment that config option is turned on.
    > Note that it also means you can't declare a static cpumask. You
    > should avoid this anyway (use cpumask_var_t), but there's a
    > deliberately-ugly workaround for special cases, using DECLARE_BITMAP()
    > and to_cpumask().
    > Signed-off-by: Rusty Russell <>
    > Cc: Arnd Bergmann <>
    > Cc:
    > Cc: KOSAKI Motohiro <>
    > Cc: Mike Travis <>

    Is there any good reason to not remove it altogether, regardless
    of whether the OFFSTACK config is set? I mean, triggering build
    failures for a relatively rarely turned on config option is
    asking for constant maintenance trouble.



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