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    SubjectRe: [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync
    On Fri, 17 Nov 2006, Paul E. McKenney wrote:

    > > Perhaps a better approach to the initialization problem would be to assume
    > > that either:
    > >
    > > 1. The srcu_struct will be initialized before it is used, or
    > >
    > > 2. When it is used before initialization, the system is running
    > > only one thread.
    > Are these assumptions valid? If so, they would indeed simplify things
    > a bit.

    I don't know. Maybe Andrew can tell us -- is it true that the kernel runs
    only one thread up through the time the core_initcalls are finished?

    If not, can we create another initcall level that is guaranteed to run
    before any threads are spawned?

    > For the moment, I cheaped out and used a mutex_trylock. If this can block,
    > I will need to add a separate spinlock to guard per_cpu_ref allocation.

    I haven't looked at your revised patch yet... But it's important to keep
    things as simple as possible.

    > Hmmm... How to test this? Time for the wrapper around alloc_percpu()
    > that randomly fails, I guess. ;-)

    Do you really want things to continue in a highly degraded mode when
    percpu allocation fails? Maybe it would be better just to pass the
    failure back to the caller.

    Alan Stern

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      Last update: 2006-11-18 05:37    [W:0.021 / U:11.900 seconds]
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