fix(bitfield): fix raw_mask shifting twice
#262
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There's currently a bug in the `raw_mask` method on `mycelium-bitfield`'s packing spec types. `raw_mask` returns `self.mask` shifted over by `self.shift`, with the intention of returning the actual mask used by the packing spec. But...the `self.mask` field is already shifted to the correct bit position, so shifting it in the `raw_mask` method results in the mask being shifted over twice as many bits as it's supposed to be. This caused some *very* weird behavior in the `maitake` task state management code, where attempting to toggle a bit using its `raw_mask` would accidentally clobber low bits of the ref count, resulting in a ref-count underflow in some cases.
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There's currently a bug in the
raw_maskmethod onmycelium-bitfield's packing spec types.raw_maskreturnsself.maskshifted over by
self.shift, with the intention of returning the actualmask used by the packing spec. But...the
self.maskfield is alreadyshifted to the correct bit position, so shifting it in the
raw_maskmethod results in the mask being shifted over twice as many bits as it's
supposed to be.
This caused some very weird behavior in the
maitaketask statemanagement code, where attempting to toggle a bit using its
raw_maskwould accidentally clobber low bits of the ref count, resulting in a
ref-count underflow in some cases.