Re: [PATCH v2 4/4] bus: Make remove callback return void

Re: [PATCH v2 4/4] bus: Make remove callback return void

[Bjorn Andersson]

On Tue 06 Jul 10:48 CDT 2021, Uwe Kleine-K?nig wrote:

> The driver core ignores the return value of this callback because there
> is only little it can do when a device disappears.
> 
> This is the final bit of a long lasting cleanup quest where several
> buses were converted to also return void from their remove callback.
> Additionally some resource leaks were fixed that were caused by drivers
> returning an error code in the expectation that the driver won't go
> away.
> 
> With struct bus_type::remove returning void it's prevented that newly
> implemented buses return an ignored error code and so don't anticipate
> wrong expectations for driver authors.
> 

Thanks for doing this!

Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org> (rpmsg and apr)

[..]
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index c1404d3dae2c..7f6fac618ab2 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -530,7 +530,7 @@ static int rpmsg_dev_probe(struct device *dev)
>  	return err;
>  }
>  
> -static int rpmsg_dev_remove(struct device *dev)
> +static void rpmsg_dev_remove(struct device *dev)
>  {
>  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
>  	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
> @@ -546,8 +546,6 @@ static int rpmsg_dev_remove(struct device *dev)
>  
>  	if (rpdev->ept)
>  		rpmsg_destroy_ept(rpdev->ept);
> -
> -	return err;

This leaves err assigned but never used, but I don't mind following up
with a patch cleaning that up after this has landed.

>  }
>  
>  static struct bus_type rpmsg_bus = {

Regards,
Bjorn

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Re: [PATCH v2 4/4] bus: Make remove callback return void

[Uwe Kleine-König]

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Hello Bjorn,

On Tue, Jul 06, 2021 at 01:08:18PM -0500, Bjorn Andersson wrote:
> On Tue 06 Jul 10:48 CDT 2021, Uwe Kleine-K?nig wrote:
> > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > index c1404d3dae2c..7f6fac618ab2 100644
> > --- a/drivers/rpmsg/rpmsg_core.c
> > +++ b/drivers/rpmsg/rpmsg_core.c
> > @@ -530,7 +530,7 @@ static int rpmsg_dev_probe(struct device *dev)
> >  	return err;
> >  }
> >  
> > -static int rpmsg_dev_remove(struct device *dev)
> > +static void rpmsg_dev_remove(struct device *dev)
> >  {
> >  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
> >  	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
> > @@ -546,8 +546,6 @@ static int rpmsg_dev_remove(struct device *dev)
> >  
> >  	if (rpdev->ept)
> >  		rpmsg_destroy_ept(rpdev->ept);
> > -
> > -	return err;
> 
> This leaves err assigned but never used, but I don't mind following up
> with a patch cleaning that up after this has landed.

Ah, good catch. If I send out a v3 I will fold the following into this
patch:

diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index 7f6fac618ab2..9151836190ce 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -534,10 +534,9 @@ static void rpmsg_dev_remove(struct device *dev)
 {
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
-	int err = 0;
 
 	if (rpdev->ops->announce_destroy)
-		err = rpdev->ops->announce_destroy(rpdev);
+		rpdev->ops->announce_destroy(rpdev);
 
 	if (rpdrv->remove)
 		rpdrv->remove(rpdev);

Maybe .announce_destroy() should then be changed to return void, too?
Something like:

diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index a76c344253bf..d5204756714c 100644
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -40,7 +40,7 @@ struct rpmsg_device_ops {
 					    struct rpmsg_channel_info chinfo);
 
 	int (*announce_create)(struct rpmsg_device *ept);
-	int (*announce_destroy)(struct rpmsg_device *ept);
+	void (*announce_destroy)(struct rpmsg_device *ept);
 };
 
 /**
diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index 8e49a3bacfc7..4e05994634f8 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -340,7 +340,7 @@ static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev)
 	return err;
 }
 
-static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
+static void virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
 {
 	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 	struct virtproc_info *vrp = vch->vrp;
@@ -360,8 +360,6 @@ static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
 		if (err)
 			dev_err(dev, "failed to announce service %d\n", err);
 	}
-
-	return err;
 }
 
 static const struct rpmsg_device_ops virtio_rpmsg_ops = {

though it's not obvious for me that the last hunk is sensible. (OTOH the
return code is ignored anyhow as rpmsg_dev_remove() is the only caller.

Best regards and thanks
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v2 4/4] bus: Make remove callback return void

[Bjorn Andersson]

On Tue 06 Jul 13:43 CDT 2021, Uwe Kleine-K?nig wrote:

> Hello Bjorn,
> 
> On Tue, Jul 06, 2021 at 01:08:18PM -0500, Bjorn Andersson wrote:
> > On Tue 06 Jul 10:48 CDT 2021, Uwe Kleine-K?nig wrote:
> > > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > > index c1404d3dae2c..7f6fac618ab2 100644
> > > --- a/drivers/rpmsg/rpmsg_core.c
> > > +++ b/drivers/rpmsg/rpmsg_core.c
> > > @@ -530,7 +530,7 @@ static int rpmsg_dev_probe(struct device *dev)
> > >  	return err;
> > >  }
> > >  
> > > -static int rpmsg_dev_remove(struct device *dev)
> > > +static void rpmsg_dev_remove(struct device *dev)
> > >  {
> > >  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
> > >  	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
> > > @@ -546,8 +546,6 @@ static int rpmsg_dev_remove(struct device *dev)
> > >  
> > >  	if (rpdev->ept)
> > >  		rpmsg_destroy_ept(rpdev->ept);
> > > -
> > > -	return err;
> > 
> > This leaves err assigned but never used, but I don't mind following up
> > with a patch cleaning that up after this has landed.
> 
> Ah, good catch. If I send out a v3 I will fold the following into this
> patch:
> 
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index 7f6fac618ab2..9151836190ce 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -534,10 +534,9 @@ static void rpmsg_dev_remove(struct device *dev)
>  {
>  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
>  	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
> -	int err = 0;
>  
>  	if (rpdev->ops->announce_destroy)
> -		err = rpdev->ops->announce_destroy(rpdev);
> +		rpdev->ops->announce_destroy(rpdev);
>  
>  	if (rpdrv->remove)
>  		rpdrv->remove(rpdev);
> 

Sounds good, feel free to keep my ack on this.

> Maybe .announce_destroy() should then be changed to return void, too?
> Something like:
> 

Yes, I saw this opportunity as well. But that will fan out further, so
let's postpone that until your series has landed and we can follow up
with such changes through the remoteproc tree.

> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> index a76c344253bf..d5204756714c 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -40,7 +40,7 @@ struct rpmsg_device_ops {
>  					    struct rpmsg_channel_info chinfo);
>  
>  	int (*announce_create)(struct rpmsg_device *ept);
> -	int (*announce_destroy)(struct rpmsg_device *ept);
> +	void (*announce_destroy)(struct rpmsg_device *ept);
>  };
>  
>  /**
> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index 8e49a3bacfc7..4e05994634f8 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -340,7 +340,7 @@ static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev)
>  	return err;
>  }
>  
> -static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
> +static void virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
>  {
>  	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
>  	struct virtproc_info *vrp = vch->vrp;
> @@ -360,8 +360,6 @@ static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
>  		if (err)
>  			dev_err(dev, "failed to announce service %d\n", err);
>  	}
> -
> -	return err;
>  }
>  
>  static const struct rpmsg_device_ops virtio_rpmsg_ops = {
> 
> though it's not obvious for me that the last hunk is sensible. (OTOH the
> return code is ignored anyhow as rpmsg_dev_remove() is the only caller.
> 

I need to backtrack a little bit more to figure out why we ended up with
this...

Thanks,
Bjorn

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Re: [PATCH v2 4/4] bus: Make remove callback return void

[William Breathitt Gray]

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On Tue, Jul 06, 2021 at 05:48:03PM +0200, Uwe Kleine-König wrote:
> The driver core ignores the return value of this callback because there
> is only little it can do when a device disappears.
> 
> This is the final bit of a long lasting cleanup quest where several
> buses were converted to also return void from their remove callback.
> Additionally some resource leaks were fixed that were caused by drivers
> returning an error code in the expectation that the driver won't go
> away.
> 
> With struct bus_type::remove returning void it's prevented that newly
> implemented buses return an ignored error code and so don't anticipate
> wrong expectations for driver authors.
> 
> Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> (For ARM, Amba and related parts)
> Acked-by: Mark Brown <broonie@kernel.org>
> Acked-by: Chen-Yu Tsai <wens@csie.org> (for drivers/bus/sunxi-rsb.c)
> Acked-by: Pali Rohár <pali@kernel.org>
> Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org> (for drivers/media)
> Acked-by: Hans de Goede <hdegoede@redhat.com> (For drivers/platform)
> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Acked-By: Vinod Koul <vkoul@kernel.org>
> Acked-by: Juergen Gross <jgross@suse.com> (For Xen)
> Acked-by: Lee Jones <lee.jones@linaro.org> (For drivers/mfd)
> Acked-by: Johannes Thumshirn <jth@kernel.org> (For drivers/mcb)
> Acked-by: Johan Hovold <johan@kernel.org>
> Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> (For drivers/slimbus)
> Acked-by: Kirti Wankhede <kwankhede@nvidia.com> (For drivers/vfio)
> Acked-by: Maximilian Luz <luzmaximilian@gmail.com>
> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> (For ulpi and typec)
> Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com> (For ipack)
> Reviewed-by: Tom Rix <trix@redhat.com> (For fpga)
> Acked-by: Geoff Levand <geoff@infradead.org> (For ps3)
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---

>  drivers/base/isa.c                        | 4 +---

Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>

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