Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

[Segher Boessenkool <segher@kernel.crashing.org>]

> > > > Part of the motivation here is to fix heisenbugs.  If I knew where 
> > > > they
> > >
> > >
> > > By the same token we should probably disable optimisations
> > > altogether since that too can create heisenbugs.
> > Almost everything is a tradeoff; and so is this.  I don't
> > believe most people would find disabling all compiler
> > optimisations an acceptable price to pay for some peace
> > of mind.
>
> So why is this a good tradeoff?

It certainly is better than disabling all compiler optimisations!

> I also think that just adding things to APIs in the hope it might fix
> up some bugs isn't really a good road to go down. Where do you stop?

I look at it the other way: keeping the "volatile" semantics in
atomic_XXX() (or adding them to it, whatever) helps _prevent_ bugs;
certainly most people expect that behaviour, and also that behaviour
is *needed* in some places and no other interface provides that
functionality.


[some confusion about barriers wrt atomics snipped]


Segher

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