linux-kernel - Re: [PATCH] dm-log-writes: Use pointers from memcpy() calls for assignments in two functions

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Message-ID: <85eba740-899c-6884-93b4-aa441436db97@redhat.com>
Date: Mon, 3 Nov 2025 17:10:15 +0100 (CET)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Markus Elfring <Markus.Elfring@....de>
cc: dm-devel@...ts.linux.dev, Alasdair Kergon <agk@...hat.com>, 
    Heinz Mauelshagen <heinzm@...hat.com>, Josef Bacik <jbacik@...com>, 
    Mike Snitzer <snitzer@...nel.org>, 
    Ross Zwisler <ross.zwisler@...ux.intel.com>, Zach Brown <zab@...bo.net>, 
    LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org, 
    Miaoqian Lin <linmq006@...il.com>
Subject: Re: [PATCH] dm-log-writes: Use pointers from memcpy() calls for
 assignments in two functions

Hi

I think that the code is more readable as it is.

Putting two function calls on one line doesn't make it easier to read.

Mikulas


On Fri, 31 Oct 2025, Markus Elfring wrote:

> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Fri, 31 Oct 2025 20:20:56 +0100
> 
> A pointer was assigned to a variable in two function implementations.
> 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 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>
> ---
>  drivers/md/dm-log-writes.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
> index 7bb7174f8f4f..b450bdadfaf2 100644
> --- a/drivers/md/dm-log-writes.c
> +++ b/drivers/md/dm-log-writes.c
> @@ -232,8 +232,7 @@ static int write_metadata(struct log_writes_c *lc, void *entry,
>  		goto error;
>  	}
>  
> -	ptr = kmap_local_page(page);
> -	memcpy(ptr, entry, entrylen);
> +	ptr = memcpy(kmap_local_page(page), entry, entrylen);
>  	if (datalen)
>  		memcpy(ptr + entrylen, data, datalen);
>  	memset(ptr + entrylen + datalen, 0,
> @@ -287,8 +286,7 @@ static int write_inline_data(struct log_writes_c *lc, void *entry,
>  				goto error_bio;
>  			}
>  
> -			ptr = kmap_local_page(page);
> -			memcpy(ptr, data, pg_datalen);
> +			ptr = memcpy(kmap_local_page(page), data, pg_datalen);
>  			if (pg_sectorlen > pg_datalen)
>  				memset(ptr + pg_datalen, 0, pg_sectorlen - pg_datalen);
>  			kunmap_local(ptr);
> -- 
> 2.51.1
>