Re: [PATCH] HID: wacom_sys: add error code check in wacom_feature_mapping

[Su Hui]

On 2023/11/6 11:57, Rahul Rameshbabu wrote:
> On Fri, 20 Oct, 2023 17:02:38 +0800 "Su Hui" <suhui@xxxxxxxxxxxx> wrote:
> > hid_report_raw_event() can return error code like '-ENOMEM' if
> > failed, so check 'ret' to make sure all things work fine.
> I can agree with adding logging for error cases personally.
>
> > Signed-off-by: Su Hui <suhui@xxxxxxxxxxxx>
> > ---
> >   drivers/hid/wacom_sys.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
> > index 3f704b8072e8..1f898d4ee708 100644
> > --- a/drivers/hid/wacom_sys.c
> > +++ b/drivers/hid/wacom_sys.c
> > @@ -320,6 +320,8 @@ static void wacom_feature_mapping(struct hid_device *hdev,
> >   			if (ret == n && features->type == HID_GENERIC) {
> >   				ret = hid_report_raw_event(hdev,
> >   					HID_FEATURE_REPORT, data, n, 0);
> > +				if (ret)
> > +					hid_warn(hdev, "failed to report feature\n");
> I think we should report the returned error information as well.
Agreed, I will send v2 soon.
Thanks for your suggestions!

Su Hui

>    https://docs.kernel.org/core-api/printk-formats.html#error-pointers
>
> Typically what I do is use ERR_PTR in tandem with the %pe modifier for
> printing errors.
>
> >   			} else if (ret == 2 && features->type != HID_GENERIC) {
> >   				features->touch_max = data[1];
> >   			} else {
> > @@ -381,6 +383,8 @@ static void wacom_feature_mapping(struct hid_device *hdev,
> >   		if (ret == n) {
> >   			ret = hid_report_raw_event(hdev, HID_FEATURE_REPORT,
> >   						   data, n, 0);
> > +			if (ret)
> > +				hid_warn(hdev, "failed to report feature\n");
> >   		} else {
> >   			hid_warn(hdev, "%s: could not retrieve sensor offsets\n",
> >   				 __func__);
> --
> Thanks for the patch,
>
> Rahul Rameshbabu