linux-kernel - Re: [PATCH] net: dsa: lan9303: correctly check return value of devm_gpiod_get

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Message-ID: <251e5e33-8bbb-d745-63c8-95d7b34d95f0@electromag.com.au>
Date:   Mon, 13 Nov 2017 12:08:49 +0800
From:   Phil Reid <preid@...ctromag.com.au>
To:     Pan Bian <bianpan2016@....com>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] net: dsa: lan9303: correctly check return value of
 devm_gpiod_get_optional

On 12/11/2017 23:38, Pan Bian wrote:
> Function devm_gpiod_get_optional() returns an ERR_PTR on failure. Its
> return value should not be validated by a NULL check. Instead, use IS_ERR.
> 
> Signed-off-by: Pan Bian <bianpan2016@....com>
> ---
>   drivers/net/dsa/lan9303-core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/lan9303-core.c b/drivers/net/dsa/lan9303-core.c
> index b471413..6d3fc8f 100644
> --- a/drivers/net/dsa/lan9303-core.c
> +++ b/drivers/net/dsa/lan9303-core.c
> @@ -828,7 +828,7 @@ static void lan9303_probe_reset_gpio(struct lan9303 *chip,
>   	chip->reset_gpio = devm_gpiod_get_optional(chip->dev, "reset",
>   						   GPIOD_OUT_LOW);
>   
> -	if (!chip->reset_gpio) {
> +	if (IS_ERR(chip->reset_gpio)) {
>   		dev_dbg(chip->dev, "No reset GPIO defined\n");
>   		return;
>   	}
> 
Should not an error actually report the error and error out (ie fail probe).
But a null is the optional return and ok. (ie when -ENOENT return from sub gpiod_get call).

IS_ERR should be a separate condition check I think.

related lan9303_handle_reset() always returns 0.

lan9303_probe checks  lan9303_handle_reset() return value.

Probably should be checking lan9303_probe_reset_gpio() instead.

-- 
Regards
Phil Reid