[PATCH] iio: proximity: Fix return value check of wait_for_completion_timeout

[PATCH] iio: proximity: Fix return value check of wait_for_completion_timeout

[Miaoqian Lin]

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@gmail.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

RE: [PATCH] iio: proximity: Fix return value check of wait_for_completion_timeout

[Sa, Nuno]

> -----Original Message-----
> From: Miaoqian Lin <linmq006@gmail.com>
> Sent: Tuesday, April 12, 2022 5:00 AM
> To: Song Qiang <songqiang1304521@gmail.com>; Jonathan Cameron
> <jic23@kernel.org>; Lars-Peter Clausen <lars@metafoo.de>; Ivan
> Drobyshevskyi <drobyshevskyi@gmail.com>; linux-
> iio@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: linmq006@gmail.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@gmail.com>
> ---

Reviewed-by: Nuno Sá <nuno.sa@analog.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

RE: [PATCH] iio: proximity: Fix return value check of wait_for_completion_timeout

[Sa, Nuno]

> From: Sa, Nuno
> Sent: Tuesday, April 12, 2022 8:21 AM
> To: Miaoqian Lin <linmq006@gmail.com>; Song Qiang
> <songqiang1304521@gmail.com>; Jonathan Cameron
> <jic23@kernel.org>; Lars-Peter Clausen <lars@metafoo.de>; Ivan
> Drobyshevskyi <drobyshevskyi@gmail.com>; linux-
> iio@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: RE: [PATCH] iio: proximity: Fix return value check of
> wait_for_completion_timeout
> 
> 
> 
> > -----Original Message-----
> > From: Miaoqian Lin <linmq006@gmail.com>
> > Sent: Tuesday, April 12, 2022 5:00 AM
> > To: Song Qiang <songqiang1304521@gmail.com>; Jonathan Cameron
> > <jic23@kernel.org>; Lars-Peter Clausen <lars@metafoo.de>; Ivan
> > Drobyshevskyi <drobyshevskyi@gmail.com>; linux-
> > iio@vger.kernel.org; linux-kernel@vger.kernel.org
> > Cc: linmq006@gmail.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@gmail.com>
> > ---
> 
> Reviewed-by: Nuno Sá <nuno.sa@analog.com>

Hi Lin,

Just one note regarding the patch subject. You should indicate
to which driver this patch applies "iio: proximity: vl53l0x: ..."

- Nuno Sá

[PATCH v2] iio: proximity: vl53l0x: Fix return value check of wait_for_completion_timeout

[Miaoqian Lin]

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@gmail.com>
---
Changes in v2:
- add driver name in patch subject.
---
 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

Re: [PATCH v2] iio: proximity: vl53l0x: Fix return value check of wait_for_completion_timeout

[Jonathan Cameron]

On Tue, 12 Apr 2022 06:42:09 +0000
Miaoqian Lin <linmq006@gmail.com> wrote:

> 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@gmail.com>
Hi,

Applied to the togreg branch of iio.git ready for the next
merge window. I'm not rushing this in because it's removing pointless
and misleading code rather than fixing a bug as such.

Thanks,

Jonathan

> ---
> Changes in v2:
> - add driver name in patch subject.
> ---
>  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);