[PATCH] nvme-hwmon: don't return errors from nvme_hwmon_init

[Serge Semin]

On Tue, Oct 18, 2022 at 09:26:24AM -0600, Keith Busch wrote:
> On Tue, Oct 18, 2022 at 05:23:09PM +0200, Christoph Hellwig wrote:
> > On Tue, Oct 18, 2022 at 09:15:08AM -0600, Keith Busch wrote:
> > > We still need to check for < 0 since nvme_hwmon_init() sends an admin
> > > command. If the admin command times out, the controller is reset and
> > > -EINTR is returned, indicating we have to abort initialization. All
> > > other errors should be ignored, though, since the controller remains
> > > usable.
> > 
> > So I guess we should just ignore everything but EINTR, e.g.:
> 
> Yep, this looks fine. You'll just need to initialize 'int err = 0;' at
> the beginning.
> 
>  
> > diff --git a/drivers/nvme/host/hwmon.c b/drivers/nvme/host/hwmon.c
> > index 0a586d7129201..aed245678315f 100644
> > --- a/drivers/nvme/host/hwmon.c
> > +++ b/drivers/nvme/host/hwmon.c
> > @@ -230,7 +230,7 @@ int nvme_hwmon_init(struct nvme_ctrl *ctrl)
> >  
> >  	data = kzalloc(sizeof(*data), GFP_KERNEL);
> >  	if (!data)
> > -		return 0;
> > +		goto err;
> >  
> >  	data->ctrl = ctrl;
> >  	mutex_init(&data->read_lock);
> > @@ -238,8 +238,7 @@ int nvme_hwmon_init(struct nvme_ctrl *ctrl)
> >  	err = nvme_hwmon_get_smart_log(data);
> >  	if (err) {
> >  		dev_warn(dev, "Failed to read smart log (error %d)\n", err);
> > -		kfree(data);
> > -		return err;
> > +		goto err_free_data;
> >  	}
> >  
> >  	hwmon = hwmon_device_register_with_info(dev, "nvme",
> > @@ -247,11 +246,22 @@ int nvme_hwmon_init(struct nvme_ctrl *ctrl)
> >  						NULL);
> >  	if (IS_ERR(hwmon)) {
> >  		dev_warn(dev, "Failed to instantiate hwmon device\n");
> > -		kfree(data);
> > -		return PTR_ERR(hwmon);
> > +		err = PTR_ERR(hwmon);
> > +		goto err_free_data;
> >  	}
> >  	ctrl->hwmon_device = hwmon;
> >  	return 0;
> > +
> > +err_free_data:
> > +	kfree(data);
> > +err:
> > +	/*
> > +	 * Do not return errors unless we are in a controller reset.
> > +	 * The controller works perfectly fine without the hwmon registration.
> > +	 */

> > +	if (err == -EINTR)
> > +		return -EINTR;

What about just taking the -EINTR error into account by the
nvme_hwmon_init() caller and ignore any other there? Meanwhile you can
convert the nvme_hwmon_init() method to return any error including the
ENOMEM. Thus the function will be more consistent and will have
independent from the caller context design.

-Sergey

> > +	return 0;
> >  }
> >  
> >  void nvme_hwmon_exit(struct nvme_ctrl *ctrl)
> > -- 
> > 2.30.2
> >