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    SubjectRe: [PATCH 0/4]: Respin local_irq_*_nmi() stuff.
    On Tue, 2010-04-13 at 00:56 -0700, David Miller wrote:

    > If we are in an NMI then doing a plain raw_local_irq_disable() will
    > write PIL_NORMAL_MAX into %pil, which is lower than PIL_NMI, and thus
    > we'll re-enable NMIs and recurse.
    > Doing a simple:
    > %pil = %pil | PIL_NORMAL_MAX
    > does what we want, if we're already at PIL_NMI (15) we leave it at
    > that setting, else we set it to PIL_NORMAL_MAX (14).

    Ah indeed, and without a conditional, very nice!

    It does rely on the exact values of the PIL_levels, it might make sense
    to note that in the comment, something like:

    * Assumes: PIL_NMI | PIL_NORMAL_MAX == PIL_NMI.

    Hmm, it also assumes %pil is never anything other than 0,
    PIL_NORMAL_MAX, PIL_NMI, because if:

    (%pil & 1) && (%pil != PIL_NMI)

    then you'll end up disabling NMIs. Could something like that ever

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      Last update: 2010-04-13 10:39    [W:0.020 / U:127.216 seconds]
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