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    SubjectRe: [PATCH] Fix the cpumask rewrite
    On Sat, Jun 26, 2004 at 11:54:24AM -0700, Linus Torvalds wrote:

    > On Sat, 26 Jun 2004, Vojtech Pavlik wrote:
    > >
    > > At least input pretty much relies on the fact that bitops don't need
    > > locking and act as memory barriers.
    > Well, plain test_bit() has always been more relaxed than the others, and
    > has never implied a memory barrier. Only the "test_and_set/clear()" things
    > imply memory barriers.

    Ouch. I'll have to revisit some code then.

    > What we _could_ do (without changing any existing rules) is to add a
    > "__test_bit()" that is the relaxed version that doesn't do any of the
    > volatile etc. That would match the "__" versions of the other bit
    > operations.
    > Then people who know that they use the bits without any volatility issues
    > can use that one, and let the compiler optimize more.
    > Hmm?

    That makes a lot of sense to me, as we already have the __ variants for
    most of the other bitops already.

    Vojtech Pavlik
    SuSE Labs, SuSE CR
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