Re: [PATCH] LLVMLinux: Remove warning about returning an uninitialized variable

[Behan Webster]

On 03/31/14 13:52, H. Peter Anvin wrote:
> On 03/21/2014 11:38 PM, behanw@xxxxxxxxxxxxxxxxxx wrote:
> > From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> >
> > Fix uninitialized return code in default case in cmpxchg-local.h
> >
> > This patch fixes the code to prevent an uninitialized return value that is detected
> > when compiling with clang. The bug produces numerous warnings when compiling the
> > Linux kernel with clang.
> >
> > Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx>
> > ---
> >   include/asm-generic/cmpxchg-local.h | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h
> > index d8d4c89..4c41bb8 100644
> > --- a/include/asm-generic/cmpxchg-local.h
> > +++ b/include/asm-generic/cmpxchg-local.h
> > @@ -41,6 +41,7 @@ static inline unsigned long __cmpxchg_local_generic(volatile void *ptr,
> >   		break;
> >   	default:
> >   		wrong_size_cmpxchg(ptr);
> > +		prev = 0;
> >   	}
> >   	raw_local_irq_restore(flags);
> >   	return prev;
> Shouldn't this be a build time assert (__compiletime_error())?
I changed it to a __noreturn on wrong_size_cmpxchg thanks to James 
Bottomley.

Which would be better?

Behan

--
Behan Webster
behanw@xxxxxxxxxxxxxxxxxx

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