linux-kernel - Re: [PATCH] x86/process: remove unused variable in __switch_to

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Date:   Tue, 17 Dec 2019 13:29:22 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Yunfeng Ye <yeyunfeng@...wei.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, luto@...nel.org, riel@...riel.com,
        dave.hansen@...el.com, longman@...hat.com, mtosatti@...hat.com,
        linux-kernel@...r.kernel.org,
        "hushiyuan@...wei.com" <hushiyuan@...wei.com>,
        "linfeilong@...wei.com" <linfeilong@...wei.com>
Subject: Re: [PATCH] x86/process: remove unused variable in __switch_to_xtra()

On Tue, Dec 17, 2019 at 08:09:08PM +0800, Yunfeng Ye wrote:
> After the commit ecc7e37d4dad ("x86/io: Speedup schedule out of I/O
> bitmap user") and commit 22fe5b0439dd ("x86/ioperm: Move TSS bitmap
> update to exit to user work"), warning is found:
> 
> arch/x86/kernel/process.c: In function ‘__switch_to_xtra’:
> arch/x86/kernel/process.c:618:31: warning: variable ‘next’ set but not
> used [-Wunused-but-set-variable]
>   struct thread_struct *prev, *next;
>                                ^~~~
> arch/x86/kernel/process.c:618:24: warning: variable ‘prev’ set but not
> used [-Wunused-but-set-variable]
>   struct thread_struct *prev, *next;
>                         ^~~~
> Fix this by removing the unused variable @prev and @next;
> 
> Signed-off-by: Yunfeng Ye <yeyunfeng@...wei.com>
> ---
>  arch/x86/kernel/process.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 61e93a318983..839b5244e3b7 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -615,12 +615,8 @@ void speculation_ctrl_update_current(void)
> 
>  void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
>  {
> -	struct thread_struct *prev, *next;
>  	unsigned long tifp, tifn;
> 
> -	prev = &prev_p->thread;
> -	next = &next_p->thread;
> -
>  	tifn = READ_ONCE(task_thread_info(next_p)->flags);
>  	tifp = READ_ONCE(task_thread_info(prev_p)->flags);
> 
> -- 

Let me introduce you to your colleague yu kuai:

https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/cleanups&id=27353d5785bca61bb49cfd7c78e14f1d21e66ec5

:-)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette