linux-kernel - RE: [PATCH v2] iio: stmpe-adc: Fix wait_for_completion

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Message-ID: <PH0PR03MB6786157EDA63137DF0071D1F99ED9@PH0PR03MB6786.namprd03.prod.outlook.com>
Date:   Tue, 12 Apr 2022 06:29:35 +0000
From:   "Sa, Nuno" <Nuno.Sa@...log.com>
To:     Miaoqian Lin <linmq006@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Kees Cook <keescook@...omium.org>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] iio: stmpe-adc: Fix wait_for_completion_timeout return
 value check



> -----Original Message-----
> From: Miaoqian Lin <linmq006@...il.com>
> Sent: Tuesday, April 12, 2022 3:56 AM
> To: Jonathan Cameron <jic23@...nel.org>; Lars-Peter Clausen
> <lars@...afoo.de>; Maxime Coquelin
> <mcoquelin.stm32@...il.com>; Alexandre Torgue
> <alexandre.torgue@...s.st.com>; Kees Cook
> <keescook@...omium.org>; Miaoqian Lin <linmq006@...il.com>;
> Philippe Schenker <philippe.schenker@...adex.com>; linux-
> iio@...r.kernel.org; linux-stm32@...md-mailman.stormreply.com;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
> Subject: [PATCH v2] iio: stmpe-adc: Fix wait_for_completion_timeout
> return value check
> 
> [External]
> 
> wait_for_completion_timeout() returns unsigned long not long.
> 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: e813dde6f833 ("iio: stmpe-adc: Use
> wait_for_completion_timeout")
> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> ---
> changes in v2:
> - Fix same issue in stmpe_read_temp.
> ---

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

(I guess the subject also needs tweaking for the preferred format)

>  drivers/iio/adc/stmpe-adc.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
> index d2d405388499..83e0ac4467ca 100644
> --- a/drivers/iio/adc/stmpe-adc.c
> +++ b/drivers/iio/adc/stmpe-adc.c
> @@ -61,7 +61,7 @@ struct stmpe_adc {
>  static int stmpe_read_voltage(struct stmpe_adc *info,
>  		struct iio_chan_spec const *chan, int *val)
>  {
> -	long ret;
> +	unsigned long ret;
> 
>  	mutex_lock(&info->lock);
> 
> @@ -79,7 +79,7 @@ static int stmpe_read_voltage(struct stmpe_adc
> *info,
> 
>  	ret = wait_for_completion_timeout(&info->completion,
> STMPE_ADC_TIMEOUT);
> 
> -	if (ret <= 0) {
> +	if (ret == 0) {
>  		stmpe_reg_write(info->stmpe,
> STMPE_REG_ADC_INT_STA,
>  				STMPE_ADC_CH(info->channel));
>  		mutex_unlock(&info->lock);
> @@ -96,7 +96,7 @@ static int stmpe_read_voltage(struct stmpe_adc
> *info,
>  static int stmpe_read_temp(struct stmpe_adc *info,
>  		struct iio_chan_spec const *chan, int *val)
>  {
> -	long ret;
> +	unsigned long ret;
> 
>  	mutex_lock(&info->lock);
> 
> @@ -114,7 +114,7 @@ static int stmpe_read_temp(struct stmpe_adc
> *info,
> 
>  	ret = wait_for_completion_timeout(&info->completion,
> STMPE_ADC_TIMEOUT);
> 
> -	if (ret <= 0) {
> +	if (ret == 0) {
>  		mutex_unlock(&info->lock);
>  		return -ETIMEDOUT;
>  	}
> --
> 2.17.1