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[PATCH v2] can: m_can: apply rate-limiting to lost msg in rx

Sean Nyekjaer posted 1 patch 7 months, 1 week ago 
drivers/net/can/m_can/m_can.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
[PATCH v2] can: m_can: apply rate-limiting to lost msg in rx
Posted by Sean Nyekjaer 7 months, 1 week ago 
Wrap the "msg lost in rxf0" error in m_can_handle_lost_msg() with
a call to net_ratelimit() to prevent flooding the kernel log
with repeated debug messages.

Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
---
Changes in v2:
- Changed to dbg msg
- Link to v1: https://lore.kernel.org/r/20250620-mcan_ratelimit-v1-1-e747ee30f71f@geanix.com
---
 drivers/net/can/m_can/m_can.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 6c656bfdb3235e1f5d6405c49b07b821ddacc1b9..9f43111609d364c01c6df10489fc4708deab9fbb 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -665,7 +665,8 @@ static int m_can_handle_lost_msg(struct net_device *dev)
 	struct can_frame *frame;
 	u32 timestamp = 0;
 
-	netdev_err(dev, "msg lost in rxf0\n");
+	if (net_ratelimit())
+		netdev_dbg(dev, "msg lost in rxf0\n");
 
 	stats->rx_errors++;
 	stats->rx_over_errors++;

---
base-commit: db22720545207f734aaa9d9f71637bfc8b0155e0
change-id: 20250620-mcan_ratelimit-e7e1f9d8fa9c

Best regards,
-- 
Sean Nyekjaer <sean@geanix.com>
Re: [PATCH v2] can: m_can: apply rate-limiting to lost msg in rx
Posted by Marc Kleine-Budde 7 months ago 
On 30.06.2025 09:52:44, Sean Nyekjaer wrote:
> Wrap the "msg lost in rxf0" error in m_can_handle_lost_msg() with
> a call to net_ratelimit() to prevent flooding the kernel log
> with repeated debug messages.
>
> Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
> Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> Signed-off-by: Sean Nyekjaer <sean@geanix.com>
> ---
> Changes in v2:
> - Changed to dbg msg
> - Link to v1: https://lore.kernel.org/r/20250620-mcan_ratelimit-v1-1-e747ee30f71f@geanix.com
> ---
>  drivers/net/can/m_can/m_can.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 6c656bfdb3235e1f5d6405c49b07b821ddacc1b9..9f43111609d364c01c6df10489fc4708deab9fbb 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -665,7 +665,8 @@ static int m_can_handle_lost_msg(struct net_device *dev)
>  	struct can_frame *frame;
>  	u32 timestamp = 0;
>
> -	netdev_err(dev, "msg lost in rxf0\n");
> +	if (net_ratelimit())
> +		netdev_dbg(dev, "msg lost in rxf0\n");

This has some subtle side effects. Even if debugging is not enabled, you
will still get the "... output lines suppressed due to ratelimiting"
message, which is IMHO very confusing :)

What about replacing the netdev_err() by netdev_dbg()?

--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -665,7 +665,7 @@ static int m_can_handle_lost_msg(struct net_device *dev)
        struct can_frame *frame;
        u32 timestamp = 0;

-       netdev_err(dev, "msg lost in rxf0\n");
+       netdev_dbg(dev, "msg lost in rxf0\n");

        stats->rx_errors++;
        stats->rx_over_errors++;

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 v2] can: m_can: apply rate-limiting to lost msg in rx
Posted by Sean Nyekjaer 7 months ago 
Hi,

On Fri, Jul 11, 2025 at 11:33:35AM +0100, Marc Kleine-Budde wrote:
> On 30.06.2025 09:52:44, Sean Nyekjaer wrote:
> > Wrap the "msg lost in rxf0" error in m_can_handle_lost_msg() with
> > a call to net_ratelimit() to prevent flooding the kernel log
> > with repeated debug messages.
> >
> > Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
> > Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> > Signed-off-by: Sean Nyekjaer <sean@geanix.com>
> > ---
> > Changes in v2:
> > - Changed to dbg msg
> > - Link to v1: https://lore.kernel.org/r/20250620-mcan_ratelimit-v1-1-e747ee30f71f@geanix.com
> > ---
> >  drivers/net/can/m_can/m_can.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> > index 6c656bfdb3235e1f5d6405c49b07b821ddacc1b9..9f43111609d364c01c6df10489fc4708deab9fbb 100644
> > --- a/drivers/net/can/m_can/m_can.c
> > +++ b/drivers/net/can/m_can/m_can.c
> > @@ -665,7 +665,8 @@ static int m_can_handle_lost_msg(struct net_device *dev)
> >  	struct can_frame *frame;
> >  	u32 timestamp = 0;
> >
> > -	netdev_err(dev, "msg lost in rxf0\n");
> > +	if (net_ratelimit())
> > +		netdev_dbg(dev, "msg lost in rxf0\n");
> 
> This has some subtle side effects. Even if debugging is not enabled, you
> will still get the "... output lines suppressed due to ratelimiting"
> message, which is IMHO very confusing :)

Indeed yes :)

> 
> What about replacing the netdev_err() by netdev_dbg()?
> 
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -665,7 +665,7 @@ static int m_can_handle_lost_msg(struct net_device *dev)
>         struct can_frame *frame;
>         u32 timestamp = 0;
> 
> -       netdev_err(dev, "msg lost in rxf0\n");
> +       netdev_dbg(dev, "msg lost in rxf0\n");
> 
>         stats->rx_errors++;
>         stats->rx_over_errors++;
> 

Yeah that will do. V3 or?

/Sean
Re: [PATCH v2] can: m_can: apply rate-limiting to lost msg in rx
Posted by Marc Kleine-Budde 7 months ago 
On 11.07.2025 09:58:53, Sean Nyekjaer wrote:
> > What about replacing the netdev_err() by netdev_dbg()?
> > 
> > --- a/drivers/net/can/m_can/m_can.c
> > +++ b/drivers/net/can/m_can/m_can.c
> > @@ -665,7 +665,7 @@ static int m_can_handle_lost_msg(struct net_device *dev)
> >         struct can_frame *frame;
> >         u32 timestamp = 0;
> > 
> > -       netdev_err(dev, "msg lost in rxf0\n");
> > +       netdev_dbg(dev, "msg lost in rxf0\n");
> > 
> >         stats->rx_errors++;
> >         stats->rx_over_errors++;
> > 
> 
> Yeah that will do. V3 or?

Yes, please.

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   |

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