linux-kernel - Re: [PATCH] power: supply: rk817: Fix unsigned comparison with less than zero

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Date:   Tue, 13 Dec 2022 08:41:50 -0600
From:   Chris Morgan <macroalpha82@...il.com>
To:     Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
Cc:     sre@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Abaci Robot <abaci@...ux.alibaba.com>
Subject: Re: [PATCH] power: supply: rk817: Fix unsigned comparison with less
 than zero

On Tue, Dec 13, 2022 at 06:19:04PM +0800, Jiapeng Chong wrote:
> The tmp is defined as u32 type, which results in invalid processing of
> tmp<0 in function rk817_read_or_set_full_charge_on_boot(). Therefore,
> change the tmp type to int.

Good catch, but I'm wondering if we shouldn't just drop the comparison
to less than zero? If I'm not mistaken get_unaligned_be32() only
returns unsigned integers anyway, right?

Assuming my understanding is right, we'll just drop the comparison.
Otherwise, this would be the appropriate fix.

Thank you for catching this!
Chris

> 
> drivers/power/supply/rk817_charger.c:828 rk817_read_or_set_full_charge_on_boot() warn: unsigned 'tmp' is never less than zero.
> drivers/power/supply/rk817_charger.c:788 rk817_read_or_set_full_charge_on_boot() warn: unsigned 'tmp' is never less than zero.
> 
> Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3444
> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
> ---
>  drivers/power/supply/rk817_charger.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/supply/rk817_charger.c b/drivers/power/supply/rk817_charger.c
> index 4f9c1c417916..7eefbcc0a4e9 100644
> --- a/drivers/power/supply/rk817_charger.c
> +++ b/drivers/power/supply/rk817_charger.c
> @@ -731,8 +731,8 @@ rk817_read_or_set_full_charge_on_boot(struct rk817_charger *charger,
>  {
>  	struct rk808 *rk808 = charger->rk808;
>  	u8 bulk_reg[4];
> -	u32 boot_voltage, boot_charge_mah, tmp;
> -	int ret, reg, off_time;
> +	u32 boot_voltage, boot_charge_mah;
> +	int ret, reg, off_time, tmp;
>  	bool first_boot;
>  
>  	/*
> -- 
> 2.20.1.7.g153144c
>