linux-kernel - Re: [PATCH] HID: core: remove unneeded assignment in hid_process

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Message-ID: <nycvar.YFH.7.76.2207211337090.19850@cbobk.fhfr.pm>
Date:   Thu, 21 Jul 2022 13:37:15 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>
cc:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, llvm@...ts.linux.dev,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: core: remove unneeded assignment in
 hid_process_report()

On Fri, 1 Jul 2022, Lukas Bulwahn wrote:

> Commit bebcc522fbee ("HID: core: for input reports, process the usages by
> priority list") split the iteration into two distinct loops in
> hid_process_report().
> 
> After this change, the variable field is only used while iterating in the
> second loop and the assignment of values to this variable in the first loop
> is simply not needed.
> 
> Remove the unneeded assignment during retrieval. No functional change and
> no change in the resulting object code.
> 
> This was discovered as a dead store with clang-analyzer.
> 
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
> ---
> Benjamin, Jiri, please pick this minor non-urgent clean-up patch.
> 
>  drivers/hid/hid-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 00154a1cd2d8..b7f5566e338d 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1662,7 +1662,7 @@ static void hid_process_report(struct hid_device *hid,
>  
>  	/* first retrieve all incoming values in data */
>  	for (a = 0; a < report->maxfield; a++)
> -		hid_input_fetch_field(hid, field = report->field[a], data);
> +		hid_input_fetch_field(hid, report->field[a], data);
>  
>  	if (!list_empty(&report->field_entry_list)) {

Applied, thanks Lukas.

-- 
Jiri Kosina
SUSE Labs