[PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Michael Walle]

Due to missing prerequisites the probe of the felix switch might be
deferred:
[    4.435305] mscc_felix 0000:00:00.5: Failed to register DSA switch: -517

It's not an error. Use dev_err_probe() to demote the error to a debug
message. While at it, replace all the dev_err()'s in the probe with
dev_err_probe().

Signed-off-by: Michael Walle <michael@walle.cc>
---

Should this be a patch with a Fixes tag?

 drivers/net/dsa/ocelot/felix_vsc9959.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 8d382b27e625..1f8c4c6de01b 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -2268,14 +2268,14 @@ static int felix_pci_probe(struct pci_dev *pdev,
 
 	err = pci_enable_device(pdev);
 	if (err) {
-		dev_err(&pdev->dev, "device enable failed\n");
+		dev_err_probe(&pdev->dev, err, "device enable failed\n");
 		goto err_pci_enable;
 	}
 
 	felix = kzalloc(sizeof(struct felix), GFP_KERNEL);
 	if (!felix) {
 		err = -ENOMEM;
-		dev_err(&pdev->dev, "Failed to allocate driver memory\n");
+		dev_err_probe(&pdev->dev, err, "Failed to allocate driver memory\n");
 		goto err_alloc_felix;
 	}
 
@@ -2293,7 +2293,7 @@ static int felix_pci_probe(struct pci_dev *pdev,
 					&felix_irq_handler, IRQF_ONESHOT,
 					"felix-intb", ocelot);
 	if (err) {
-		dev_err(&pdev->dev, "Failed to request irq\n");
+		dev_err_probe(&pdev->dev, err, "Failed to request irq\n");
 		goto err_alloc_irq;
 	}
 
@@ -2316,7 +2316,7 @@ static int felix_pci_probe(struct pci_dev *pdev,
 
 	err = dsa_register_switch(ds);
 	if (err) {
-		dev_err(&pdev->dev, "Failed to register DSA switch: %d\n", err);
+		dev_err_probe(&pdev->dev, err, "Failed to register DSA switch\n");
 		goto err_register_ds;
 	}
 
-- 
2.30.2

Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Vladimir Oltean]

On Thu, Apr 07, 2022 at 03:06:25PM +0200, Michael Walle wrote:
> Due to missing prerequisites the probe of the felix switch might be
> deferred:
> [    4.435305] mscc_felix 0000:00:00.5: Failed to register DSA switch: -517
> 
> It's not an error. Use dev_err_probe() to demote the error to a debug
> message. While at it, replace all the dev_err()'s in the probe with
> dev_err_probe().
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---

Please limit the dev_err_probe() to dsa_register_switch(). The resource
that is missing is the DSA master, see of_find_net_device_by_node().
The others cannot possibly return -EPROBE_DEFER.

> 
> Should this be a patch with a Fixes tag?

Whichever way you wish, no preference.

> 
>  drivers/net/dsa/ocelot/felix_vsc9959.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
> index 8d382b27e625..1f8c4c6de01b 100644
> --- a/drivers/net/dsa/ocelot/felix_vsc9959.c
> +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
> @@ -2268,14 +2268,14 @@ static int felix_pci_probe(struct pci_dev *pdev,
>  
>  	err = pci_enable_device(pdev);
>  	if (err) {
> -		dev_err(&pdev->dev, "device enable failed\n");
> +		dev_err_probe(&pdev->dev, err, "device enable failed\n");
>  		goto err_pci_enable;
>  	}
>  
>  	felix = kzalloc(sizeof(struct felix), GFP_KERNEL);
>  	if (!felix) {
>  		err = -ENOMEM;
> -		dev_err(&pdev->dev, "Failed to allocate driver memory\n");
> +		dev_err_probe(&pdev->dev, err, "Failed to allocate driver memory\n");
>  		goto err_alloc_felix;
>  	}
>  
> @@ -2293,7 +2293,7 @@ static int felix_pci_probe(struct pci_dev *pdev,
>  					&felix_irq_handler, IRQF_ONESHOT,
>  					"felix-intb", ocelot);
>  	if (err) {
> -		dev_err(&pdev->dev, "Failed to request irq\n");
> +		dev_err_probe(&pdev->dev, err, "Failed to request irq\n");
>  		goto err_alloc_irq;
>  	}
>  
> @@ -2316,7 +2316,7 @@ static int felix_pci_probe(struct pci_dev *pdev,
>  
>  	err = dsa_register_switch(ds);
>  	if (err) {
> -		dev_err(&pdev->dev, "Failed to register DSA switch: %d\n", err);
> +		dev_err_probe(&pdev->dev, err, "Failed to register DSA switch\n");
>  		goto err_register_ds;
>  	}
>  
> -- 
> 2.30.2
>

Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Michael Walle]

Am 2022-04-07 15:56, schrieb Vladimir Oltean:
> On Thu, Apr 07, 2022 at 03:06:25PM +0200, Michael Walle wrote:
>> Due to missing prerequisites the probe of the felix switch might be
>> deferred:
>> [    4.435305] mscc_felix 0000:00:00.5: Failed to register DSA switch: 
>> -517
>> 
>> It's not an error. Use dev_err_probe() to demote the error to a debug
>> message. While at it, replace all the dev_err()'s in the probe with
>> dev_err_probe().
>> 
>> Signed-off-by: Michael Walle <michael@walle.cc>
>> ---
> 
> Please limit the dev_err_probe() to dsa_register_switch(). The resource
> that is missing is the DSA master, see of_find_net_device_by_node().
> The others cannot possibly return -EPROBE_DEFER.

This was my rationale (from the function doc):

  * Note that it is deemed acceptable to use this function for error
  * prints during probe even if the @err is known to never be 
-EPROBE_DEFER.
  * The benefit compared to a normal dev_err() is the standardized format
  * of the error code and the fact that the error code is returned.

In any case I don't have a strong opinion.

>> 
>> Should this be a patch with a Fixes tag?
> 
> Whichever way you wish, no preference.

I'll limit it to just the one dev_err() and add a Fixes,
there might be scripts out there who greps dmesg for errors.

-michael

Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Vladimir Oltean]

On Thu, Apr 07, 2022 at 04:04:20PM +0200, Michael Walle wrote:
> Am 2022-04-07 15:56, schrieb Vladimir Oltean:
> > On Thu, Apr 07, 2022 at 03:06:25PM +0200, Michael Walle wrote:
> > > Due to missing prerequisites the probe of the felix switch might be
> > > deferred:
> > > [    4.435305] mscc_felix 0000:00:00.5: Failed to register DSA
> > > switch: -517
> > > 
> > > It's not an error. Use dev_err_probe() to demote the error to a debug
> > > message. While at it, replace all the dev_err()'s in the probe with
> > > dev_err_probe().
> > > 
> > > Signed-off-by: Michael Walle <michael@walle.cc>
> > > ---
> > 
> > Please limit the dev_err_probe() to dsa_register_switch(). The resource
> > that is missing is the DSA master, see of_find_net_device_by_node().
> > The others cannot possibly return -EPROBE_DEFER.
> 
> This was my rationale (from the function doc):
> 
>  * Note that it is deemed acceptable to use this function for error
>  * prints during probe even if the @err is known to never be -EPROBE_DEFER.
>  * The benefit compared to a normal dev_err() is the standardized format
>  * of the error code and the fact that the error code is returned.
> 
> In any case I don't have a strong opinion.

Take this case:

 		err = -ENOMEM;
-		dev_err(&pdev->dev, "Failed to allocate driver memory\n");
+		dev_err_probe(&pdev->dev, err, "Failed to allocate driver memory\n");

(1) there is no need to print ENOMEM if we say "failed to allocate memory"
(2) we don't use the return value of dev_err_probe() anyway, we have
    actual teardown to do (pci_disable_device).
(3) we _surely_ know that -ENOMEM != -EPROBE_DEFER

> 
> > > 
> > > Should this be a patch with a Fixes tag?
> > 
> > Whichever way you wish, no preference.
> 
> I'll limit it to just the one dev_err() and add a Fixes,
> there might be scripts out there who greps dmesg for errors.

Ok.

Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Michael Walle]

Am 2022-04-07 16:12, schrieb Vladimir Oltean:
> On Thu, Apr 07, 2022 at 04:04:20PM +0200, Michael Walle wrote:
>> Am 2022-04-07 15:56, schrieb Vladimir Oltean:
>> > On Thu, Apr 07, 2022 at 03:06:25PM +0200, Michael Walle wrote:
>> > > Due to missing prerequisites the probe of the felix switch might be
>> > > deferred:
>> > > [    4.435305] mscc_felix 0000:00:00.5: Failed to register DSA
>> > > switch: -517
>> > >
>> > > It's not an error. Use dev_err_probe() to demote the error to a debug
>> > > message. While at it, replace all the dev_err()'s in the probe with
>> > > dev_err_probe().
>> > >
>> > > Signed-off-by: Michael Walle <michael@walle.cc>
>> > > ---
>> >
>> > Please limit the dev_err_probe() to dsa_register_switch(). The resource
>> > that is missing is the DSA master, see of_find_net_device_by_node().
>> > The others cannot possibly return -EPROBE_DEFER.
>> 
>> This was my rationale (from the function doc):
>> 
>>  * Note that it is deemed acceptable to use this function for error
>>  * prints during probe even if the @err is known to never be 
>> -EPROBE_DEFER.
>>  * The benefit compared to a normal dev_err() is the standardized 
>> format
>>  * of the error code and the fact that the error code is returned.
>> 
>> In any case I don't have a strong opinion.
> 
> Take this case:
> 
>  		err = -ENOMEM;
> -		dev_err(&pdev->dev, "Failed to allocate driver memory\n");
> +		dev_err_probe(&pdev->dev, err, "Failed to allocate driver 
> memory\n");
> 
> (1) there is no need to print ENOMEM if we say "failed to allocate 
> memory"

That was actually a brain fart of mine ;) But AFAIK there is no need in
reporting ENOMEM errors anyway.

-michael

> (2) we don't use the return value of dev_err_probe() anyway, we have
>     actual teardown to do (pci_disable_device).
> (3) we _surely_ know that -ENOMEM != -EPROBE_DEFER
>> 
>> > >
>> > > Should this be a patch with a Fixes tag?
>> >
>> > Whichever way you wish, no preference.
>> 
>> I'll limit it to just the one dev_err() and add a Fixes,
>> there might be scripts out there who greps dmesg for errors.
> 
> Ok.

Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Michael Walle]

>> > > Should this be a patch with a Fixes tag?
>> >
>> > Whichever way you wish, no preference.
>> 
>> I'll limit it to just the one dev_err() and add a Fixes,
>> there might be scripts out there who greps dmesg for errors.
> 
> Ok.

Hum, it's not that easy. The issue goes back all the way
to the initial commit if I didn't miss anything (56051948773e).
That one was first included in 5.5, but dev_err_probe() wasn't
added until 5.9.

Thus will it work if I add Fixes: 56051948773e (..)?

-michael

Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors

[Jakub Kicinski]

On Thu, 07 Apr 2022 16:58:43 +0200 Michael Walle wrote:
> >> I'll limit it to just the one dev_err() and add a Fixes,
> >> there might be scripts out there who greps dmesg for errors.  
> > 
> > Ok.  
> 
> Hum, it's not that easy. The issue goes back all the way
> to the initial commit if I didn't miss anything (56051948773e).
> That one was first included in 5.5, but dev_err_probe() wasn't
> added until 5.9.
> 
> Thus will it work if I add Fixes: 56051948773e (..)?

Yes, backporters will figure it out. Matters even less since none 
of [5.5, 5.9] kernels are LTS.

But if you want to slap a Fixes tag on it, it has to go to net rather
than net-next.