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    SubjectRe: spin_unlock optimization(i386)

    duh, the code is ok, but this pseudocode is buggy:

    > CPU0 CPU1
    >
    > for (;;) { for (;;) {
    > i++; a = j;
    > j++; b = i;
    > } if (a < b)
    > BUG()
    > }

    the correct one is:

    CPU0 CPU1

    for (;;) { for (;;) {
    i++; b = j;
    j++; a = i;
    } if (a < b)
    BUG();
    }

    the 'symmetric' test:

    CPU0 CPU1

    for (;;) { for (;;) {
    i1++; i2++;
    j1++; j2++;
    b = j2; b = j1;
    a = i2; a = i1;
    if (a < b) if (a < b)
    BUG(); BUG();
    } }


    [plus the real code deals with the overflow case as well]

    -- mingo


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