[PATCH] staging: comedi: comedi_test: return error when comedi_test_init fails

[PATCH] staging: comedi: comedi_test: return error when comedi_test_init fails

[Chuhong Yuan]

comedi_test_init() forgets to return error when it fails.
Modify the return value to fix it.

Fixes: 9ff7400bd38c ("Staging: comedi: drivers: comedi_test: Add auto-configuration capability")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
 drivers/staging/comedi/drivers/comedi_test.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index ef4c7c8a2b71..133ed99a89f1 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -799,12 +799,14 @@ static int __init comedi_test_init(void)
 	if (!config_mode) {
 		ctcls = class_create(THIS_MODULE, CLASS_NAME);
 		if (IS_ERR(ctcls)) {
+			ret = PTR_ERR(ctcls);
 			pr_warn("comedi_test: unable to create class\n");
 			goto clean3;
 		}
 
 		ctdev = device_create(ctcls, NULL, MKDEV(0, 0), NULL, DEV_NAME);
 		if (IS_ERR(ctdev)) {
+			ret = PTR_ERR(ctdev);
 			pr_warn("comedi_test: unable to create device\n");
 			goto clean2;
 		}
@@ -826,7 +828,7 @@ static int __init comedi_test_init(void)
 clean3:
 	ctcls = NULL;
 
-	return 0;
+	return ret;
 }
 module_init(comedi_test_init);
 
-- 
2.24.0

[PATCH] staging: comedi: comedi_test: return error when comedi_test_init fails

[Chuhong Yuan]

comedi_test_init() forgets to return error when it fails.
Modify the return value to fix it.

Fixes: 9ff7400bd38c ("Staging: comedi: drivers: comedi_test: Add auto-configuration capability")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
 drivers/staging/comedi/drivers/comedi_test.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index ef4c7c8a2b71..133ed99a89f1 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -799,12 +799,14 @@ static int __init comedi_test_init(void)
 	if (!config_mode) {
 		ctcls = class_create(THIS_MODULE, CLASS_NAME);
 		if (IS_ERR(ctcls)) {
+			ret = PTR_ERR(ctcls);
 			pr_warn("comedi_test: unable to create class\n");
 			goto clean3;
 		}
 
 		ctdev = device_create(ctcls, NULL, MKDEV(0, 0), NULL, DEV_NAME);
 		if (IS_ERR(ctdev)) {
+			ret = PTR_ERR(ctdev);
 			pr_warn("comedi_test: unable to create device\n");
 			goto clean2;
 		}
@@ -826,7 +828,7 @@ static int __init comedi_test_init(void)
 clean3:
 	ctcls = NULL;
 
-	return 0;
+	return ret;
 }
 module_init(comedi_test_init);
 
-- 
2.24.0

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Re: [PATCH] staging: comedi: comedi_test: return error when comedi_test_init fails

[Ian Abbott]

On 10/12/2019 09:14, Chuhong Yuan wrote:
> comedi_test_init() forgets to return error when it fails.
> Modify the return value to fix it.
> 
> Fixes: 9ff7400bd38c ("Staging: comedi: drivers: comedi_test: Add auto-configuration capability")
> Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> ---
>   drivers/staging/comedi/drivers/comedi_test.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
> index ef4c7c8a2b71..133ed99a89f1 100644
> --- a/drivers/staging/comedi/drivers/comedi_test.c
> +++ b/drivers/staging/comedi/drivers/comedi_test.c
> @@ -799,12 +799,14 @@ static int __init comedi_test_init(void)
>   	if (!config_mode) {
>   		ctcls = class_create(THIS_MODULE, CLASS_NAME);
>   		if (IS_ERR(ctcls)) {
> +			ret = PTR_ERR(ctcls);
>   			pr_warn("comedi_test: unable to create class\n");
>   			goto clean3;
>   		}
>   
>   		ctdev = device_create(ctcls, NULL, MKDEV(0, 0), NULL, DEV_NAME);
>   		if (IS_ERR(ctdev)) {
> +			ret = PTR_ERR(ctdev);
>   			pr_warn("comedi_test: unable to create device\n");
>   			goto clean2;
>   		}
> @@ -826,7 +828,7 @@ static int __init comedi_test_init(void)
>   clean3:
>   	ctcls = NULL;
>   
> -	return 0;
> +	return ret;
>   }
>   module_init(comedi_test_init);
>   
> 

I suspect the current behaviour was by design because the module is not 
completely broken if it fails to create the "comedi_test" device.  The 
module will just behave as if the "noauto" module parameter (which sets 
the 'config_mode' variable) was set to "true" if there is an error 
during class or device creation.  That's probably why the kernel log 
messages are written with 'pr_warn()' rather than 'pr_err()'.

As long as the core "comedi" module has been loaded with the 
"comedi_num_legacy_minors" module parameter set to a non-zero value, it 
would still be possible to configure one of the "legacy" comedi devices 
to use the "comedi_test" driver via the COMEDI_DEVCONFIG ioctl.

However, returning an error might be preferable here, especially since 
the comedi core module's "comedi_num_legacy_minors" parameter defaults 
to zero.

I'm happy with the change of behaviour, but would suggest changing the 
'pr_warn()' calls to 'pr_err()' to match this change.

-- 
-=( Ian Abbott <abbotti@mev.co.uk> || Web: www.mev.co.uk )=-
-=( MEV Ltd. is a company registered in England & Wales. )=-
-=( Registered number: 02862268.  Registered address:    )=-
-=( 15 West Park Road, Bramhall, STOCKPORT, SK7 3JZ, UK. )=-

Re: [PATCH] staging: comedi: comedi_test: return error when comedi_test_init fails

[Ian Abbott]

On 10/12/2019 09:14, Chuhong Yuan wrote:
> comedi_test_init() forgets to return error when it fails.
> Modify the return value to fix it.
> 
> Fixes: 9ff7400bd38c ("Staging: comedi: drivers: comedi_test: Add auto-configuration capability")
> Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> ---
>   drivers/staging/comedi/drivers/comedi_test.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
> index ef4c7c8a2b71..133ed99a89f1 100644
> --- a/drivers/staging/comedi/drivers/comedi_test.c
> +++ b/drivers/staging/comedi/drivers/comedi_test.c
> @@ -799,12 +799,14 @@ static int __init comedi_test_init(void)
>   	if (!config_mode) {
>   		ctcls = class_create(THIS_MODULE, CLASS_NAME);
>   		if (IS_ERR(ctcls)) {
> +			ret = PTR_ERR(ctcls);
>   			pr_warn("comedi_test: unable to create class\n");
>   			goto clean3;
>   		}
>   
>   		ctdev = device_create(ctcls, NULL, MKDEV(0, 0), NULL, DEV_NAME);
>   		if (IS_ERR(ctdev)) {
> +			ret = PTR_ERR(ctdev);
>   			pr_warn("comedi_test: unable to create device\n");
>   			goto clean2;
>   		}
> @@ -826,7 +828,7 @@ static int __init comedi_test_init(void)
>   clean3:
>   	ctcls = NULL;
>   
> -	return 0;
> +	return ret;
>   }
>   module_init(comedi_test_init);
>   
> 

I suspect the current behaviour was by design because the module is not 
completely broken if it fails to create the "comedi_test" device.  The 
module will just behave as if the "noauto" module parameter (which sets 
the 'config_mode' variable) was set to "true" if there is an error 
during class or device creation.  That's probably why the kernel log 
messages are written with 'pr_warn()' rather than 'pr_err()'.

As long as the core "comedi" module has been loaded with the 
"comedi_num_legacy_minors" module parameter set to a non-zero value, it 
would still be possible to configure one of the "legacy" comedi devices 
to use the "comedi_test" driver via the COMEDI_DEVCONFIG ioctl.

However, returning an error might be preferable here, especially since 
the comedi core module's "comedi_num_legacy_minors" parameter defaults 
to zero.

I'm happy with the change of behaviour, but would suggest changing the 
'pr_warn()' calls to 'pr_err()' to match this change.

-- 
-=( Ian Abbott <abbotti@mev.co.uk> || Web: www.mev.co.uk )=-
-=( MEV Ltd. is a company registered in England & Wales. )=-
-=( Registered number: 02862268.  Registered address:    )=-
-=( 15 West Park Road, Bramhall, STOCKPORT, SK7 3JZ, UK. )=-
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