Re: [Xen-devel] Re: [PATCH 01/04] Kexec / Kdump: Generic code

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 16/10/06 15:03, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:

> The comment attached to every use of xchg() is dubious. We don't specify
> warn_unused_result on that function so there's no good reason for the
> compiler to complain about discarding the result. If it's a reproducible
> problem it needs investigating. We shouldn't work around a broken compiler.

Ok, this seems to be a new 'feature' of gcc4, which has widened the class of
things it will complain about with -Wunused-value. Basically any cast of a
value causes the compiler to see an expression whose value must not be
discarded -- what a pain! This seems to me that it could mean that ignoring
return value of any function becomes potentially dangerous, as the function
may be a macro that includes a cast on the return value.

I think the fix is -Wno-unused-value. :-) It's about the least useful of the
-Wunused-<foo> warnings anyway.

I'll check this in, so please just get rid of the if(xchg()) hacky
workaround.

 -- Keir



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