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

[Chris Metcalf]

(Resending as plain text.  Not sure what Thunderbird was smoking to make
this message multipart/alternative originally...)

On 11/30/2015 12:36 PM, Frederic Weisbecker wrote:
> On Tue, Nov 24, 2015 at 04:48:35PM -0500, Chris Metcalf wrote:
> > >Unless you want to take a big diversion into atomics, I'd be tempted
> > >to leave Peter's macro alone and just write it off as necessary evil
> > >to handle the fact that thread_info.flags is all kinds of different sizes
> > >and types on different platforms, and definitely never an atomic_t.
> > >Instead just create an inline function atomic_return_or(), or
> > >whatever name you prefer, that operates on an atomic_t, and use
> > >the atomic_t type for your structure field.  It's clearly a win to mark
> > >the data types as being atomic to the extent we can do so, I think.
> I agree that cmpxchg, test_and_set_bit, fetch_or... functions with loose
> namespaces aren't the best layout.
>
> But casting thread_info to atomic_t really worries me, I'm not sure the ending
> result would be correct at all. I prefer to sacrify correctness over namespace
> sanity:-)

Just to clear, I wasn't suggesting that that necessarily was the way for you to go.
The last four lines of my message quoted above are what I think might be the
best way forward, and don't involve messing with thread_info at all.

--
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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