linux-kernel - Re: [PATCH v2] ACPI: nfit: remove redundant assignment if nfit

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Date:   Fri, 10 Aug 2018 23:45:35 +0000
From:   "Verma, Vishal L" <vishal.l.verma@...el.com>
To:     "Williams, Dan J" <dan.j.williams@...el.com>,
        "ross.zwisler@...ux.intel.com" <ross.zwisler@...ux.intel.com>,
        "oceanhehy@...il.com" <oceanhehy@...il.com>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "hehy1@...ovo.com" <hehy1@...ovo.com>
Subject: Re: [PATCH v2] ACPI: nfit: remove redundant assignment if nfit_mem
 found


On Thu, 2018-08-02 at 04:44 -0400, oceanhehy@...il.com wrote:
> From: Ocean He <hehy1@...ovo.com>
> 
> When nfit_mem is found via list_for_each_entry, it has already been
> assigned valid value. There is no need to assign it again in the
> following
> codes.
> 
> Signed-off-by: Ocean He <hehy1@...ovo.com>
> ---
> v1: https://patchwork.kernel.org/patch/10553277/
> v2: Sorry for noise. I got an email problem, so I have to resend to
> loop 
> linux-nvdimm@...ts.01.org.
> 
>  drivers/acpi/nfit/core.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index 7c47900..85dde54 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -1048,9 +1048,7 @@ static int __nfit_mem_init(struct
> acpi_nfit_desc *acpi_desc,
>  				break;
>  			}
>  
> -		if (found)
> -			nfit_mem = found;
> -		else {
> +		if (!found) {

Hi Ocean,

While this is technically correct, the old way was easier to read. We
loop through and find the matching handle. If we found one, then
nfit_mem was whatever was found. If not, we allocate it.

With this change, one has to go grok the list_for_.. loop to figure out
where nfit_mem is coming from. I'd personally prefer to keep the
existing way..

>  			nfit_mem = devm_kzalloc(acpi_desc->dev,
>  					sizeof(*nfit_mem),
> GFP_KERNEL);
>  			if (!nfit_mem)