linux-kernel - RE: [PATCH] iio: proximity: Fix return value check of wait_for_completion

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Message-ID: <PH0PR03MB67863270EC86D06606F1E44E99ED9@PH0PR03MB6786.namprd03.prod.outlook.com>
Date:   Tue, 12 Apr 2022 06:21:15 +0000
From:   "Sa, Nuno" <Nuno.Sa@...log.com>
To:     Miaoqian Lin <linmq006@...il.com>,
        Song Qiang <songqiang1304521@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Ivan Drobyshevskyi <drobyshevskyi@...il.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] iio: proximity: Fix return value check of
 wait_for_completion_timeout



> -----Original Message-----
> From: Miaoqian Lin <linmq006@...il.com>
> Sent: Tuesday, April 12, 2022 5:00 AM
> To: Song Qiang <songqiang1304521@...il.com>; Jonathan Cameron
> <jic23@...nel.org>; Lars-Peter Clausen <lars@...afoo.de>; Ivan
> Drobyshevskyi <drobyshevskyi@...il.com>; linux-
> iio@...r.kernel.org; linux-kernel@...r.kernel.org
> Cc: linmq006@...il.com
> Subject: [PATCH] iio: proximity: Fix return value check of
> wait_for_completion_timeout
> 
> [External]
> 
> wait_for_completion_timeout() returns unsigned long not int.
> It returns 0 if timed out, and positive if completed.
> The check for <= 0 is ambiguous and should be == 0 here
> indicating timeout which is the only error case.
> 
> Fixes: 3cef2e31b54b ("iio: proximity: vl53l0x: Add IRQ support")
> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> ---

Reviewed-by: Nuno Sá <nuno.sa@...log.com>

>  drivers/iio/proximity/vl53l0x-i2c.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/proximity/vl53l0x-i2c.c
> b/drivers/iio/proximity/vl53l0x-i2c.c
> index 661a79ea200d..a284b20529fb 100644
> --- a/drivers/iio/proximity/vl53l0x-i2c.c
> +++ b/drivers/iio/proximity/vl53l0x-i2c.c
> @@ -104,6 +104,7 @@ static int vl53l0x_read_proximity(struct
> vl53l0x_data *data,
>  	u16 tries = 20;
>  	u8 buffer[12];
>  	int ret;
> +	unsigned long time_left;
> 
>  	ret = i2c_smbus_write_byte_data(client,
> VL_REG_SYSRANGE_START, 1);
>  	if (ret < 0)
> @@ -112,10 +113,8 @@ static int vl53l0x_read_proximity(struct
> vl53l0x_data *data,
>  	if (data->client->irq) {
>  		reinit_completion(&data->completion);
> 
> -		ret = wait_for_completion_timeout(&data-
> >completion, HZ/10);
> -		if (ret < 0)
> -			return ret;
> -		else if (ret == 0)
> +		time_left = wait_for_completion_timeout(&data-
> >completion, HZ/10);
> +		if (time_left == 0)
>  			return -ETIMEDOUT;
> 
>  		vl53l0x_clear_irq(data);
> --
> 2.17.1