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    Subject[PATCHSET] stop_machine: implement stop_machine_from_offline_cpu()
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    Hello,

    This three patch series implements stop_machine_from_offline_cpu(),
    which is stop_machine() which can be used from a CPU which isn't yet
    online.

    This is for mtrr which needs stop_machine while bringing up a CPU. It
    currently implements its own stop_machine directly using
    stop_one_cpu(). Duplicating such core functionality is wasteful and
    fragile. e.g. mtrr's implementation currently can deadlock against
    generic stop_machine().

    This patchset is born from Suresh's attempt at implementing similar
    feature into [__]stop_machine()[1], which IMHO is a bit too subtle.
    Given the peculiarity of the feature, I think it's better to have
    dedicated function with an ugly name. Also, this way, the
    implementation is very well isolated from the rest of stop_cpus
    machinery and much simpler.

    This patchset contains the following three patches.

    0001-stop_machine-kill-__stop_machine.patch
    0002-stop_machine-reorganize-stop_cpus-implementation.patch
    0003-stop_machine-implement-stop_machine_from_offline_cpu.patch

    0001 is a cleanup patch which can go in regardless of the rest (with
    ack from x86 people of course). 0002 is pure code reorganization.
    0003 implements the feature.

    Suresh, how does this look to you? Can you please put the mtrr
    changes on top of this and see how it works?

    arch/x86/kernel/alternative.c | 5 -
    include/linux/stop_machine.h | 42 +++------------
    kernel/cpu.c | 2
    kernel/stop_machine.c | 117 +++++++++++++++++++++++++++++++++++-------
    4 files changed, 114 insertions(+), 52 deletions(-)

    Thanks.

    --
    tejun

    [1] http://thread.gmane.org/gmane.linux.kernel/1154383/focus=1154384


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