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

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Date:   Fri, 1 Jul 2022 05:44:48 -0700
From:   Tom Rix <trix@...hat.com>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.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 7/1/22 4:27 AM, 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)) {
>   		/* INPUT_REPORT, we have a priority list of fields */
Reviewed-by: Tom Rix <trix@...hat.com>