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SubjectRe: [PATCH] staging: comedi: comedi_test: return error when comedi_test_init fails
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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 )=-
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