linux-kernel - Re: [PATCH] MIPS: Remove incorrect NULL check in local_flush_tlb

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Message-ID: <CAOiHx==kyY9ce5jjv5m36OXpG9Vk4NsPa9m+nfWuYWjxOnMisA@mail.gmail.com>
Date:	Sun, 6 Jul 2014 12:22:25 +0200
From:	Jonas Gorski <jogo@...nwrt.org>
To:	Emil Goode <emilgoode@...il.com>
Cc:	Ralf Baechle <ralf@...ux-mips.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	John Crispin <blogic@...nwrt.org>,
	MIPS Mailing List <linux-mips@...ux-mips.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] MIPS: Remove incorrect NULL check in local_flush_tlb_page()

On Sun, Jul 6, 2014 at 1:23 AM, Emil Goode <emilgoode@...il.com> wrote:
> We check that the struct vm_area_struct pointer vma is NULL and then
> dereference it a few lines below. The intent was to make sure vma is
> not NULL but this is not necessary since the bug pre-dates GIT history
> and seem to never have caused a problem. The tlb-4k and tlb-8k versions
> of local_flush_tlb_page() don't bother checking if vma is NULL, also
> vma is dereferenced before being passed to local_flush_tlb_page(),
> thus it is safe to remove this NULL check.
>
> Signed-off-by: Emil Goode <emilgoode@...il.com>

Looks good.

Reviewed-by: Jonas Gorski <jogo@...nwrt.org>

> ---
>  arch/mips/mm/tlb-r3k.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/mm/tlb-r3k.c b/arch/mips/mm/tlb-r3k.c
> index d657493..4094bbd 100644
> --- a/arch/mips/mm/tlb-r3k.c
> +++ b/arch/mips/mm/tlb-r3k.c
> @@ -158,7 +158,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
>  {
>         int cpu = smp_processor_id();
>
> -       if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
> +       if (cpu_context(cpu, vma->vm_mm) != 0) {
>                 unsigned long flags;
>                 int oldpid, newpid, idx;
>
> --
> 1.7.10.4
>
>
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