ptp: create "pins" together with the rest of attributes

BugLink: https://bugs.launchpad.net/bugs/1881356

commit 85a66e55 upstream.

Let's switch to using device_create_with_groups(), which will allow us to
create "pins" attribute group together with the rest of ptp device
attributes, and before userspace gets notified about ptp device creation.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

drivers/ptp/ptp_clock.c

@@ -214,16 +214,17 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	mutex_init(&ptp->pincfg_mux);
 	init_waitqueue_head(&ptp->tsev_wq);
 
+	err = ptp_populate_pin_groups(ptp);
+	if (err)
+		goto no_pin_groups;
+
 	/* Create a new device in our class. */
-	ptp->dev = device_create(ptp_class, parent, ptp->devid, ptp,
+	ptp->dev = device_create_with_groups(ptp_class, parent, ptp->devid,
+					     ptp, ptp->pin_attr_groups,
 					     "ptp%d", ptp->index);
 	if (IS_ERR(ptp->dev))
 		goto no_device;
 
-	err = ptp_populate_sysfs(ptp);
-	if (err)
-		goto no_sysfs;
-
 	/* Register a new PPS source. */
 	if (info->pps) {
 		struct pps_source_info pps;
@@ -251,10 +252,10 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (ptp->pps_source)
 		pps_unregister_source(ptp->pps_source);
 no_pps:
-	ptp_cleanup_sysfs(ptp);
-no_sysfs:
 	device_destroy(ptp_class, ptp->devid);
 no_device:
+	ptp_cleanup_pin_groups(ptp);
+no_pin_groups:
 	mutex_destroy(&ptp->tsevq_mux);
 	mutex_destroy(&ptp->pincfg_mux);
 no_slot:
@@ -272,8 +273,9 @@ int ptp_clock_unregister(struct ptp_clock *ptp)
 	/* Release the clock's resources. */
 	if (ptp->pps_source)
 		pps_unregister_source(ptp->pps_source);
-	ptp_cleanup_sysfs(ptp);
+
 	device_destroy(ptp_class, ptp->devid);
+	ptp_cleanup_pin_groups(ptp);
 
 	posix_clock_unregister(&ptp->clock);
 	return 0;

drivers/ptp/ptp_private.h

@@ -54,6 +54,8 @@ struct ptp_clock {
 	struct device_attribute *pin_dev_attr;
 	struct attribute **pin_attr;
 	struct attribute_group pin_attr_group;
+	/* 1st entry is a pointer to the real group, 2nd is NULL terminator */
+	const struct attribute_group *pin_attr_groups[2];
 };
 
 /*
@@ -94,8 +96,7 @@ uint ptp_poll(struct posix_clock *pc,
 
 extern const struct attribute_group *ptp_groups[];
 
-int ptp_cleanup_sysfs(struct ptp_clock *ptp);
-
-int ptp_populate_sysfs(struct ptp_clock *ptp);
+int ptp_populate_pin_groups(struct ptp_clock *ptp);
+void ptp_cleanup_pin_groups(struct ptp_clock *ptp);
 
 #endif

drivers/ptp/ptp_sysfs.c

@@ -268,24 +268,13 @@ static ssize_t ptp_pin_store(struct device *dev, struct device_attribute *attr,
 	return count;
 }
 
-int ptp_cleanup_sysfs(struct ptp_clock *ptp)
+int ptp_populate_pin_groups(struct ptp_clock *ptp)
 {
-	struct device *dev = ptp->dev;
 	struct ptp_clock_info *info = ptp->info;
+	int err = -ENOMEM, i, n_pins = info->n_pins;
 
-	if (info->n_pins) {
-		sysfs_remove_group(&dev->kobj, &ptp->pin_attr_group);
-		kfree(ptp->pin_attr);
-		kfree(ptp->pin_dev_attr);
-	}
+	if (!n_pins)
 		return 0;
-}
-
-static int ptp_populate_pins(struct ptp_clock *ptp)
-{
-	struct device *dev = ptp->dev;
-	struct ptp_clock_info *info = ptp->info;
-	int err = -ENOMEM, i, n_pins = info->n_pins;
 
 	ptp->pin_dev_attr = kzalloc(n_pins * sizeof(*ptp->pin_dev_attr),
 				    GFP_KERNEL);
@@ -310,28 +299,18 @@ static int ptp_populate_pins(struct ptp_clock *ptp)
 	ptp->pin_attr_group.name = "pins";
 	ptp->pin_attr_group.attrs = ptp->pin_attr;
 
-	err = sysfs_create_group(&dev->kobj, &ptp->pin_attr_group);
-	if (err)
-		goto no_group;
+	ptp->pin_attr_groups[0] = &ptp->pin_attr_group;
+
 	return 0;
 
-no_group:
-	kfree(ptp->pin_attr);
 no_pin_attr:
 	kfree(ptp->pin_dev_attr);
 no_dev_attr:
 	return err;
 }
 
-int ptp_populate_sysfs(struct ptp_clock *ptp)
+void ptp_cleanup_pin_groups(struct ptp_clock *ptp)
 {
-	struct ptp_clock_info *info = ptp->info;
-	int err;
-
-	if (info->n_pins) {
-		err = ptp_populate_pins(ptp);
-		if (err)
-			return err;
-	}
-	return 0;
+	kfree(ptp->pin_attr);
+	kfree(ptp->pin_dev_attr);
 }