can: dev: can_set_termination(): Allow gpio sleep

[PATCH] can: dev: can_set_termination(): Allow gpio sleep

Posted by Nicolai Buchwitz 2 days, 11 hours ago

The current implementation of can_set_termination() sets the GPIO in a
context which cannot sleep. This is an issue if the GPIO controller can
sleep (e.g. since the concerning GPIO expander is connected via SPI or
I2C). Thus, if the termination resistor is set (eg. with ip link),
a warning splat will be issued in the kernel log.

Fix this by setting the termination resistor with
gpiod_set_value_cansleep() which instead of gpiod_set_value() allows it to
sleep.

Cc: stable@vger.kernel.org
Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
---
 drivers/net/can/dev/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/dev/dev.c b/drivers/net/can/dev/dev.c
index 6792c14fd7eb..681643ab3780 100644
--- a/drivers/net/can/dev/dev.c
+++ b/drivers/net/can/dev/dev.c
@@ -468,7 +468,7 @@ static int can_set_termination(struct net_device *ndev, u16 term)
 	else
 		set = 0;
 
-	gpiod_set_value(priv->termination_gpio, set);
+	gpiod_set_value_cansleep(priv->termination_gpio, set);
 
 	return 0;
 }
-- 
2.39.5

Re: [PATCH] can: dev: can_set_termination(): Allow gpio sleep

Posted by Marc Kleine-Budde 2 days, 11 hours ago

Hello Nicolai,

thanks for your contribution!

On 21.11.2024 16:02:09, Nicolai Buchwitz wrote:
> The current implementation of can_set_termination() sets the GPIO in a
> context which cannot sleep. This is an issue if the GPIO controller can
> sleep (e.g. since the concerning GPIO expander is connected via SPI or
> I2C). Thus, if the termination resistor is set (eg. with ip link),
> a warning splat will be issued in the kernel log.
> 
> Fix this by setting the termination resistor with
> gpiod_set_value_cansleep() which instead of gpiod_set_value() allows it to
> sleep.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>

I've send the same patch a few hours ago:

https://lore.kernel.org/all/20241121-dev-fix-can_set_termination-v1-1-41fa6e29216d@pengutronix.de/

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

Re: [PATCH] can: dev: can_set_termination(): Allow gpio sleep

Posted by Lino Sanfilippo 2 days, 11 hours ago

Hi,

On 21.11.24 16:12, Marc Kleine-Budde wrote:
> Hello Nicolai,
> 
> thanks for your contribution!
> 
> On 21.11.2024 16:02:09, Nicolai Buchwitz wrote:
>> The current implementation of can_set_termination() sets the GPIO in a
>> context which cannot sleep. This is an issue if the GPIO controller can
>> sleep (e.g. since the concerning GPIO expander is connected via SPI or
>> I2C). Thus, if the termination resistor is set (eg. with ip link),
>> a warning splat will be issued in the kernel log.
>>
>> Fix this by setting the termination resistor with
>> gpiod_set_value_cansleep() which instead of gpiod_set_value() allows it to
>> sleep.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
> 
> I've send the same patch a few hours ago:
> 
> https://lore.kernel.org/all/20241121-dev-fix-can_set_termination-v1-1-41fa6e29216d@pengutronix.de/
> 
> Marc
> 

Shouldnt this also go to stable?

Regards,
Lino

Re: [PATCH] can: dev: can_set_termination(): Allow gpio sleep

Posted by Marc Kleine-Budde 2 days, 11 hours ago

On 21.11.2024 16:17:53, Lino Sanfilippo wrote:
> > On 21.11.2024 16:02:09, Nicolai Buchwitz wrote:
> >> The current implementation of can_set_termination() sets the GPIO in a
> >> context which cannot sleep. This is an issue if the GPIO controller can
> >> sleep (e.g. since the concerning GPIO expander is connected via SPI or
> >> I2C). Thus, if the termination resistor is set (eg. with ip link),
> >> a warning splat will be issued in the kernel log.
> >>
> >> Fix this by setting the termination resistor with
> >> gpiod_set_value_cansleep() which instead of gpiod_set_value() allows it to
> >> sleep.
> >>
> >> Cc: stable@vger.kernel.org
> >> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
> > 
> > I've send the same patch a few hours ago:
> > 
> > https://lore.kernel.org/all/20241121-dev-fix-can_set_termination-v1-1-41fa6e29216d@pengutronix.de/
> > 
> Shouldnt this also go to stable?

Until today no-one complained about the problem, but I'll add stable on
Cc while applying the patch.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

Re: [PATCH] can: dev: can_set_termination(): Allow gpio sleep

Posted by Lino Sanfilippo 2 days, 11 hours ago


On 21.11.24 16:25, Marc Kleine-Budde wrote:
> On 21.11.2024 16:17:53, Lino Sanfilippo wrote:
>>> On 21.11.2024 16:02:09, Nicolai Buchwitz wrote:
>>>> The current implementation of can_set_termination() sets the GPIO in a
>>>> context which cannot sleep. This is an issue if the GPIO controller can
>>>> sleep (e.g. since the concerning GPIO expander is connected via SPI or
>>>> I2C). Thus, if the termination resistor is set (eg. with ip link),
>>>> a warning splat will be issued in the kernel log.
>>>>
>>>> Fix this by setting the termination resistor with
>>>> gpiod_set_value_cansleep() which instead of gpiod_set_value() allows it to
>>>> sleep.
>>>>
>>>> Cc: stable@vger.kernel.org
>>>> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
>>>
>>> I've send the same patch a few hours ago:
>>>
>>> https://lore.kernel.org/all/20241121-dev-fix-can_set_termination-v1-1-41fa6e29216d@pengutronix.de/
>>>
>> Shouldnt this also go to stable?
> 
> Until today no-one complained about the problem, but I'll add stable on
> Cc while applying the patch.
> 
> regards,
> Marc
> 

Great, thanks!

BR,
Lino