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SubjectRe: [PATCH 1/1] XEN: enlighten, use uninitialized_var(cx)

* Jiri Slaby <jirislaby@gmail.com> wrote:

> To avoid a wrong compiler warning, use unitialized_var(cx) in
> xen_init_cpuid_mask.
>
> cx needn't be initialized for cpuid when ax is 1.
>
> Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
> Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
> Cc: Chris Wright <chrisw@sous-sol.org>
> ---
> arch/x86/xen/enlighten.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index e90540a..5ab75e2 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -202,7 +202,7 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
>
> static __init void xen_init_cpuid_mask(void)
> {
> - unsigned int ax, bx, cx, dx;
> + unsigned int ax, bx, uninitialized_var(cx), dx;

Please dont use uninitialized_var(), it's an unreliable facility: if
this variable ever grows a real used-without-initialization bug in
the future, the compiler warning is turned off permanently. It's
rare but might happen. We are better off with initializing it to
zero.

Ingo


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