Re: [PATCH 1/7] atomic: Export fetch_or()

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/7] atomic: Export fetch_or()
Date	2015-11-25 10:20 +0100
Message-ID	<qyEp4-4c9-13@gated-at.bofh.it> (permalink)
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On Tue, Nov 24, 2015 at 10:19:52PM +0100, Frederic Weisbecker wrote:
> Also note that or_return() means that you first do OR and then return the new value.

Yes, that's useless. OR is an irreversible operator, which means
or_return() looses data. You can never say if a bit included in the
mask was set before.

You really must have fetch_or().
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Re: [PATCH 1/7] atomic: Export fetch_or() Chris Metcalf <cmetcalf@ezchip.com> - 2015-11-24 17:00 +0100
  Re: [PATCH 1/7] atomic: Export fetch_or() Frederic Weisbecker <fweisbec@gmail.com> - 2015-11-24 22:30 +0100
    Re: [PATCH 1/7] atomic: Export fetch_or() Chris Metcalf <cmetcalf@ezchip.com> - 2015-11-24 22:50 +0100
    Re: [PATCH 1/7] atomic: Export fetch_or() Peter Zijlstra <peterz@infradead.org> - 2015-11-25 10:20 +0100

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