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    SubjectRe: [PATCH 02/16] x86, mce: call-in should be after updating global_nwo
    From
    2009/6/15 Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>:
    > At the beginning of Monarch synchronization, processors wait until
    > all of them have entered the exception handler and then check the
    > global_nwo to determine if any of them saw a fatal event.
    >
    > However since current code does call-in before updating global_nwo,
    > it might happen that the global_nwo does not reflect some of local
    > nwo at the time.  This might break printing corrected errors not
    > handled yet on panic.

    This is almost same as the patch that I just posted. I think this is
    because it trigger a failure in mce-test suite, and we both find the
    failure.

    But your patch lacks memory barrier between mce_callin and global_nwo
    updating/reading. Atomic operations does not imply memory barrier.

    Best Regards,
    Huang Ying
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