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    SubjectRe: bitmaps/bitops
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    Date
    On Sun, 2003-03-16 at 01:31, Pete Zaitcev wrote:
    > > but the prototype for test_and_set_bit() depends on $(ARCH), and it's
    > > not consistent, with the second arg (bitmap address) being one of:
    > > volatile void *
    > > void *
    > > volatile unsigned long *
    >
    > It should be unsigned long pointer. I have no idea why
    > volatile is still alive. Perhaps Linus can remember why he
    > left it in on is386. Other arch maintainers midnlessly ape him
    > in this area. I think I even kept his e-mail where he explains
    > why volatile has to go.

    Several 2.4 drivers assume the test_and_set point is a memory
    barrier for locking. Lots of

    if(test_and_set_bit(0, &foo))
    {
    x=foodev->blah

    Since its inline code and not a memory barrier otherwise there
    is little stop the compile doing

    x=foodev->blah

    first

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