linux-kernel - Re: [PATCH] x86/resctrl: remove redundant assignment to variable chunks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Ya/jpoUWCy5shYI6@otcwcpicx3.sc.intel.com>
Date:   Tue, 7 Dec 2021 22:43:50 +0000
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Colin Ian King <colin.i.king@...il.com>
Cc:     Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/resctrl: remove redundant assignment to variable
 chunks

On Tue, Dec 07, 2021 at 10:37:35PM +0000, Colin Ian King wrote:
> The variable chunks is being shifted right and re-assinged the shifted
> value which is then returned. Since chunks is not being read afterwards
> the assignment is redundant and the >>= operator can be replaced with a
> shift >> operator instead.
> 
> Signed-off-by: Colin Ian King <colin.i.king@...il.com>
> ---
>  arch/x86/kernel/cpu/resctrl/monitor.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index c9f0f3d63f75..eaf25a234ff5 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -282,7 +282,7 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
>  	u64 shift = 64 - width, chunks;
>  
>  	chunks = (cur_msr << shift) - (prev_msr << shift);
> -	return chunks >>= shift;
> +	return chunks >> shift;
>  }
>  
>  static u64 __mon_event_count(u32 rmid, struct rmid_read *rr)

Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>

Thanks.

-Fenghua