[PATCH] PNP: handle sysfs errors

[PATCH] PNP: handle sysfs errors

[Jeff Garzik]

Signed-off-by: Jeff Garzik <jeff@garzik.org>

---

 drivers/pnp/card.c      |   30 +++++++++++++++++++++---------
 drivers/pnp/interface.c |   17 ++++++++++++++---
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/drivers/pnp/card.c b/drivers/pnp/card.c
index 227600c..91c047a 100644
--- a/drivers/pnp/card.c
+++ b/drivers/pnp/card.c
@@ -164,9 +164,17 @@ static DEVICE_ATTR(card_id,S_IRUGO,pnp_s
 
 static int pnp_interface_attach_card(struct pnp_card *card)
 {
-	device_create_file(&card->dev,&dev_attr_name);
-	device_create_file(&card->dev,&dev_attr_card_id);
+	int rc = device_create_file(&card->dev,&dev_attr_name);
+	if (rc) return rc;
+
+	rc = device_create_file(&card->dev,&dev_attr_card_id);
+	if (rc) goto err_name;
+
 	return 0;
+
+err_name:
+	device_remove_file(&card->dev,&dev_attr_name);
+	return rc;
 }
 
 /**
@@ -306,16 +314,20 @@ found:
 	down_write(&dev->dev.bus->subsys.rwsem);
 	dev->card_link = clink;
 	dev->dev.driver = &drv->link.driver;
-	if (pnp_bus_type.probe(&dev->dev)) {
-		dev->dev.driver = NULL;
-		dev->card_link = NULL;
-		up_write(&dev->dev.bus->subsys.rwsem);
-		return NULL;
-	}
-	device_bind_driver(&dev->dev);
+	if (pnp_bus_type.probe(&dev->dev))
+		goto err_out;
+	if (device_bind_driver(&dev->dev))
+		goto err_out;
+
 	up_write(&dev->dev.bus->subsys.rwsem);
 
 	return dev;
+
+err_out:
+	dev->dev.driver = NULL;
+	dev->card_link = NULL;
+	up_write(&dev->dev.bus->subsys.rwsem);
+	return NULL;
 }
 
 /**
diff --git a/drivers/pnp/interface.c b/drivers/pnp/interface.c
index 9d8b415..ac9fcd4 100644
--- a/drivers/pnp/interface.c
+++ b/drivers/pnp/interface.c
@@ -461,8 +461,19 @@ static DEVICE_ATTR(id,S_IRUGO,pnp_show_c
 
 int pnp_interface_attach_device(struct pnp_dev *dev)
 {
-	device_create_file(&dev->dev,&dev_attr_options);
-	device_create_file(&dev->dev,&dev_attr_resources);
-	device_create_file(&dev->dev,&dev_attr_id);
+	int rc = device_create_file(&dev->dev,&dev_attr_options);
+	if (rc) goto err;
+	rc = device_create_file(&dev->dev,&dev_attr_resources);
+	if (rc) goto err_opt;
+	rc = device_create_file(&dev->dev,&dev_attr_id);
+	if (rc) goto err_res;
+
 	return 0;
+
+err_res:
+	device_remove_file(&dev->dev,&dev_attr_resources);
+err_opt:
+	device_remove_file(&dev->dev,&dev_attr_options);
+err:
+	return rc;
 }

Re: [PATCH] PNP: handle sysfs errors

[Andrew Morton]

On Wed, 11 Oct 2006 17:51:09 -0400
Jeff Garzik <jeff@garzik.org> wrote:

> +	int rc = device_create_file(&dev->dev,&dev_attr_options);
> +	if (rc) goto err;
> +	rc = device_create_file(&dev->dev,&dev_attr_resources);
> +	if (rc) goto err_opt;
> +	rc = device_create_file(&dev->dev,&dev_attr_id);
> +	if (rc) goto err_res;
> +
>  	return 0;
> +
> +err_res:
> +	device_remove_file(&dev->dev,&dev_attr_resources);
> +err_opt:
> +	device_remove_file(&dev->dev,&dev_attr_options);
> +err:
> +	return rc;

That's a common pattern, isn't it?

I wonder if we could create some sort of automatic-unwinding engine:

int pnp_interface_attach_device(struct pnp_dev *dev)
{
	struct unwind_engine *u = NULL;
	int err;

	u = UNWINDABLE(u, err, device_create_file(&dev->dev,&dev_attr_options),
			device_remove_file, &dev->dev, &dev_attr_options);
	u = UNWINDABLE(u, err, device_create_file(&dev->dev,&dev_attr_id)
			device_remove_file, &dev->dev, &dev_attr_options);
	u = UNWINDABLE(u, err, device_create_file(&dev->dev,&dev_attr_id),
			device_remove_file, &dev->dev, &dev_attr_id);
	err = unwind(err, u);
	return err;
}

and, umm,

#define UNWINDABLE(u, err, expr, undo_fn, arg1, arg2)
	if (err == 0) {
		err = (expr);
		if (err == 0)
			u = add_unwind(u, undo_fn, arg1, arg2);
	}
	u;

int unwind(int err, struct unwind_engine *u)
{
	if (err == 0)
		return 0;
	for (all entries in u in opposite order) {
		u->fn(u->arg0, u>arg1);
		kfree(u);
	}
	return err;
}


I dunno - probably too crappy to live, but it'd encourage/help people to
dtrt.

Re: [PATCH] PNP: handle sysfs errors

[Dmitry Torokhov]

On Wednesday 11 October 2006 18:45, Andrew Morton wrote:
> On Wed, 11 Oct 2006 17:51:09 -0400
> Jeff Garzik <jeff@garzik.org> wrote:
> 
> > +	int rc = device_create_file(&dev->dev,&dev_attr_options);
> > +	if (rc) goto err;
> > +	rc = device_create_file(&dev->dev,&dev_attr_resources);
> > +	if (rc) goto err_opt;
> > +	rc = device_create_file(&dev->dev,&dev_attr_id);
> > +	if (rc) goto err_res;
> > +
> >  	return 0;
> > +
> > +err_res:
> > +	device_remove_file(&dev->dev,&dev_attr_resources);
> > +err_opt:
> > +	device_remove_file(&dev->dev,&dev_attr_options);
> > +err:
> > +	return rc;
> 
> That's a common pattern, isn't it?
> 
> I wonder if we could create some sort of automatic-unwinding engine:
> 
> int pnp_interface_attach_device(struct pnp_dev *dev)
> {
> 	struct unwind_engine *u = NULL;
> 	int err;
> 
> 	u = UNWINDABLE(u, err, device_create_file(&dev->dev,&dev_attr_options),
> 			device_remove_file, &dev->dev, &dev_attr_options);
> 	u = UNWINDABLE(u, err, device_create_file(&dev->dev,&dev_attr_id)
> 			device_remove_file, &dev->dev, &dev_attr_options);
> 	u = UNWINDABLE(u, err, device_create_file(&dev->dev,&dev_attr_id),
> 			device_remove_file, &dev->dev, &dev_attr_id);
> 	err = unwind(err, u);
> 	return err;
> }
> 
> and, umm,
> 
> #define UNWINDABLE(u, err, expr, undo_fn, arg1, arg2)
> 	if (err == 0) {
> 		err = (expr);
> 		if (err == 0)
> 			u = add_unwind(u, undo_fn, arg1, arg2);
> 	}
> 	u;
> 
> int unwind(int err, struct unwind_engine *u)
> {
> 	if (err == 0)
> 		return 0;
> 	for (all entries in u in opposite order) {
> 		u->fn(u->arg0, u>arg1);
> 		kfree(u);
> 	}
> 	return err;
> }
> 
> 
> I dunno - probably too crappy to live, but it'd encourage/help people to
> dtrt.

The best solution is to switch drivers with more than 2 attributes
to use arribute groups which collapses unwinding nicely.

-- 
Dmitry