linux-kernel - Re: [PATCH] x86/hyperv: Use pointer from memcpy() call for assignment in hv_crash_setup

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Message-ID: <20251031182615.GB2612078@liuwe-devbox-debian-v2.local>
Date: Fri, 31 Oct 2025 18:26:15 +0000
From: Wei Liu <wei.liu@...nel.org>
To: Markus Elfring <Markus.Elfring@....de>
Cc: linux-hyperv@...r.kernel.org, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Dexuan Cui <decui@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Long Li <longli@...rosoft.com>,
	Mukesh Rathor <mrathor@...ux.microsoft.com>,
	Thomas Gleixner <tglx@...utronix.de>, Wei Liu <wei.liu@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org, Miaoqian Lin <linmq006@...il.com>
Subject: Re: [PATCH] x86/hyperv: Use pointer from memcpy() call for
 assignment in hv_crash_setup_trampdata()

On Fri, Oct 31, 2025 at 09:33:17AM +0100, Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Fri, 31 Oct 2025 09:24:31 +0100
> 
> A pointer was assigned to a variable. The same pointer was used for
> the destination parameter of a memcpy() call.
> This function is documented in the way that the same value is returned.
> Thus convert two separate statements into a direct variable assignment for
> the return value from a memory copy action.
> 
> The source code was transformed by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  arch/x86/hyperv/hv_crash.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/x86/hyperv/hv_crash.c b/arch/x86/hyperv/hv_crash.c
> index c0e22921ace1..745d02066308 100644
> --- a/arch/x86/hyperv/hv_crash.c
> +++ b/arch/x86/hyperv/hv_crash.c
> @@ -464,9 +464,7 @@ static int hv_crash_setup_trampdata(u64 trampoline_va)
>  		return -1;
>  	}
>  
> -	dest = (void *)trampoline_va;
> -	memcpy(dest, &hv_crash_asm32, size);
> -
> +	dest = memcpy((void *)trampoline_va, &hv_crash_asm32, size);

I don't think this change is needed.

There aren't that many places in the kernel tree that use this pattern.
The pattern used by the original code is far more pervasive.

Wei

>  	dest += size;
>  	dest = (void *)round_up((ulong)dest, 16);
>  	tramp = (struct hv_crash_tramp_data *)dest;
> -- 
> 2.51.1
>