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Is it necessary to use cmpxchg when clear a bit of MaskAndCount? #74

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lastweek opened this issue Jul 4, 2019 · 0 comments
Open

Is it necessary to use cmpxchg when clear a bit of MaskAndCount? #74

lastweek opened this issue Jul 4, 2019 · 0 comments

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@lastweek
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lastweek commented Jul 4, 2019

Hi,

Quick question about MaskAndCount.

It could be read by multiple threads concurrently, thus a final compare_and_swap is necessary to guarantee atomicity.

But is it only being cleared by one single thread (the one who owns it)? If so, it seems a simple atomic clear_bit() is enough rather than full-fledged cmpxchg. Related code here.
@lastweek lastweek changed the title About MaskAndCount Is it necessary to use cmpxchg when clear a bit of MaskAndCount? Jul 4, 2019
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