[v2,10/16] KVM: PPC: Book3S PR: Remove uninitialized_var() usage
diff mbox series

Message ID 20200620033007.1444705-11-keescook@chromium.org
State New
Headers show
Series
  • Remove uninitialized_var() macro
Related show

Commit Message

Kees Cook June 20, 2020, 3:30 a.m. UTC
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings (e.g.
"unused variable"). If the compiler thinks it is uninitialized, either
simply initialize the variable or make compiler changes. As a precursor
to removing[2] this[3] macro[4], just remove this variable since it was
actually unused:

arch/powerpc/kvm/book3s_pr.c:1832:16: warning: unused variable 'vrsave' [-Wunused-variable]
        unsigned long vrsave;
                      ^

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Fixes: f05ed4d56e9c ("KVM: PPC: Split out code from book3s.c into book3s_pr.c")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/powerpc/kvm/book3s_pr.c | 3 ---
 1 file changed, 3 deletions(-)

Comments

Nick Desaulniers June 22, 2020, 5:22 p.m. UTC | #1
On Fri, Jun 19, 2020 at 8:30 PM Kees Cook <keescook@chromium.org> wrote:
>
> Using uninitialized_var() is dangerous as it papers over real bugs[1]
> (or can in the future), and suppresses unrelated compiler warnings (e.g.
> "unused variable"). If the compiler thinks it is uninitialized, either
> simply initialize the variable or make compiler changes. As a precursor
> to removing[2] this[3] macro[4], just remove this variable since it was
> actually unused:
>
> arch/powerpc/kvm/book3s_pr.c:1832:16: warning: unused variable 'vrsave' [-Wunused-variable]
>         unsigned long vrsave;
>                       ^
>
> [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
>
> Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
> Fixes: f05ed4d56e9c ("KVM: PPC: Split out code from book3s.c into book3s_pr.c")
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  arch/powerpc/kvm/book3s_pr.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index ef54f917bdaf..ed12dfbf9bb5 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -1828,9 +1828,6 @@ static int kvmppc_vcpu_run_pr(struct kvm_vcpu *vcpu)
>  {
>         struct kvm_run *run = vcpu->run;
>         int ret;
> -#ifdef CONFIG_ALTIVEC
> -       unsigned long uninitialized_var(vrsave);
> -#endif
>
>         /* Check if we can run the vcpu at all */
>         if (!vcpu->arch.sane) {
> --

Patch
diff mbox series

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index ef54f917bdaf..ed12dfbf9bb5 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1828,9 +1828,6 @@  static int kvmppc_vcpu_run_pr(struct kvm_vcpu *vcpu)
 {
 	struct kvm_run *run = vcpu->run;
 	int ret;
-#ifdef CONFIG_ALTIVEC
-	unsigned long uninitialized_var(vrsave);
-#endif
 
 	/* Check if we can run the vcpu at all */
 	if (!vcpu->arch.sane) {