linux-kernel - Re: [PATCH] powerpc/cputable: Use pointer from memcpy() call for assignment in set_cur_cpu

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Message-ID: <3115e03a-1995-46f4-a902-47ba3cb99901@csgroup.eu>
Date: Tue, 4 Nov 2025 10:34:26 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Markus Elfring <Markus.Elfring@....de>, linuxppc-dev@...ts.ozlabs.org,
 Dmitry Vyukov <dvyukov@...gle.com>, Madhavan Srinivasan
 <maddy@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>,
 Nicholas Piggin <npiggin@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org,
 Miaoqian Lin <linmq006@...il.com>
Subject: Re: [PATCH] powerpc/cputable: Use pointer from memcpy() call for
 assignment in set_cur_cpu_spec()



Le 30/10/2025 à 21:15, Markus Elfring a écrit :
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Thu, 30 Oct 2025 21:10:11 +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.

I can't see the added value of this change. For me it degrades 
readability. Many places in cputable.c have that t = PTRRELOC(t) 
pattern, I can't see why that one should be changed while other ones remain.

Can you elaborate why this change is desirable ?

Thanks
Christophe

> 
> The source code was transformed by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>   arch/powerpc/kernel/cputable.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
> index 6f6801da9dc1..a69ea88b780f 100644
> --- a/arch/powerpc/kernel/cputable.c
> +++ b/arch/powerpc/kernel/cputable.c
> @@ -34,12 +34,11 @@ void __init set_cur_cpu_spec(struct cpu_spec *s)
>   {
>   	struct cpu_spec *t = &the_cpu_spec;
>   
> -	t = PTRRELOC(t);
>   	/*
>   	 * use memcpy() instead of *t = *s so that GCC replaces it
>   	 * by __memcpy() when KASAN is active
>   	 */
> -	memcpy(t, s, sizeof(*t));
> +	t = memcpy(PTRRELOC(t), s, sizeof(*t));
>   
>   	*PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
>   }