Merge branch 'ptp-attribute-cleanup'

Dmitry Torokhov says:

====================
PTP attribute handling cleanup

PTP core was creating some attributes, such as "period" and "fifo", and the
entire "pins" attribute group, after creating class deevice, which creates
a race for userspace: uevent may arrive before all attributes are created.

This series of patches switches PTP to use is_visible() to control
visibility of attributes in a group, and device_create_with_groups() to
ensure that attributes are created before we notify userspace of a new
device.

v2:
- added Richard's acked-by to patch #1
- removed use of kmalloc_array in favor of kcalloc in patch #2 at
  Richard's request
- added a cover letter

v1:
- initial patch set
====================
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_clock.c

@@ -221,18 +221,17 @@ 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%d", ptp->index);
+	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;
 
-	dev_set_drvdata(ptp->dev, ptp);
-
-	err = ptp_populate_sysfs(ptp);
-	if (err)
-		goto no_sysfs;
-
 	/* Register a new PPS source. */
 	if (info->pps) {
 		struct pps_source_info pps;
@@ -260,10 +259,10 @@ 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);
 	ida_simple_remove(&ptp_clocks_map, index);
@@ -282,8 +281,9 @@ 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

@@ -46,27 +46,6 @@ PTP_SHOW_INT(n_periodic_outputs, n_per_out);
 PTP_SHOW_INT(n_programmable_pins, n_pins);
 PTP_SHOW_INT(pps_available, pps);
 
-static struct attribute *ptp_attrs[] = {
-	&dev_attr_clock_name.attr,
-	&dev_attr_max_adjustment.attr,
-	&dev_attr_n_alarms.attr,
-	&dev_attr_n_external_timestamps.attr,
-	&dev_attr_n_periodic_outputs.attr,
-	&dev_attr_n_programmable_pins.attr,
-	&dev_attr_pps_available.attr,
-	NULL,
-};
-
-static const struct attribute_group ptp_group = {
-	.attrs = ptp_attrs,
-};
-
-const struct attribute_group *ptp_groups[] = {
-	&ptp_group,
-	NULL,
-};
-
-
 static ssize_t extts_enable_store(struct device *dev,
 				  struct device_attribute *attr,
 				  const char *buf, size_t count)
@@ -91,6 +70,7 @@ static ssize_t extts_enable_store(struct device *dev,
 out:
 	return err;
 }
+static DEVICE_ATTR(extts_enable, 0220, NULL, extts_enable_store);
 
 static ssize_t extts_fifo_show(struct device *dev,
 			       struct device_attribute *attr, char *page)
@@ -124,6 +104,7 @@ static ssize_t extts_fifo_show(struct device *dev,
 	mutex_unlock(&ptp->tsevq_mux);
 	return cnt;
 }
+static DEVICE_ATTR(fifo, 0444, extts_fifo_show, NULL);
 
 static ssize_t period_store(struct device *dev,
 			    struct device_attribute *attr,
@@ -151,6 +132,7 @@ static ssize_t period_store(struct device *dev,
 out:
 	return err;
 }
+static DEVICE_ATTR(period, 0220, NULL, period_store);
 
 static ssize_t pps_enable_store(struct device *dev,
 				struct device_attribute *attr,
@@ -177,6 +159,57 @@ static ssize_t pps_enable_store(struct device *dev,
 out:
 	return err;
 }
+static DEVICE_ATTR(pps_enable, 0220, NULL, pps_enable_store);
+
+static struct attribute *ptp_attrs[] = {
+	&dev_attr_clock_name.attr,
+
+	&dev_attr_max_adjustment.attr,
+	&dev_attr_n_alarms.attr,
+	&dev_attr_n_external_timestamps.attr,
+	&dev_attr_n_periodic_outputs.attr,
+	&dev_attr_n_programmable_pins.attr,
+	&dev_attr_pps_available.attr,
+
+	&dev_attr_extts_enable.attr,
+	&dev_attr_fifo.attr,
+	&dev_attr_period.attr,
+	&dev_attr_pps_enable.attr,
+	NULL
+};
+
+static umode_t ptp_is_attribute_visible(struct kobject *kobj,
+					struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_clock_info *info = ptp->info;
+	umode_t mode = attr->mode;
+
+	if (attr == &dev_attr_extts_enable.attr ||
+	    attr == &dev_attr_fifo.attr) {
+		if (!info->n_ext_ts)
+			mode = 0;
+	} else if (attr == &dev_attr_period.attr) {
+		if (!info->n_per_out)
+			mode = 0;
+	} else if (attr == &dev_attr_pps_enable.attr) {
+		if (!info->pps)
+			mode = 0;
+	}
+
+	return mode;
+}
+
+static const struct attribute_group ptp_group = {
+	.is_visible	= ptp_is_attribute_visible,
+	.attrs		= ptp_attrs,
+};
+
+const struct attribute_group *ptp_groups[] = {
+	&ptp_group,
+	NULL
+};
 
 static int ptp_pin_name2index(struct ptp_clock *ptp, const char *name)
 {
@@ -235,47 +268,20 @@ static ssize_t ptp_pin_store(struct device *dev, struct device_attribute *attr,
 	return count;
 }
 
-static DEVICE_ATTR(extts_enable, 0220, NULL, extts_enable_store);
-static DEVICE_ATTR(fifo,         0444, extts_fifo_show, NULL);
-static DEVICE_ATTR(period,       0220, NULL, period_store);
-static DEVICE_ATTR(pps_enable,   0220, NULL, pps_enable_store);
-
-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;
-
-	if (info->n_ext_ts) {
-		device_remove_file(dev, &dev_attr_extts_enable);
-		device_remove_file(dev, &dev_attr_fifo);
-	}
-	if (info->n_per_out)
-		device_remove_file(dev, &dev_attr_period);
-
-	if (info->pps)
-		device_remove_file(dev, &dev_attr_pps_enable);
-
-	if (info->n_pins) {
-		sysfs_remove_group(&dev->kobj, &ptp->pin_attr_group);
-		kfree(ptp->pin_attr);
-		kfree(ptp->pin_dev_attr);
-	}
-	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),
+	if (!n_pins)
+		return 0;
+
+	ptp->pin_dev_attr = kcalloc(n_pins, sizeof(*ptp->pin_dev_attr),
 				    GFP_KERNEL);
 	if (!ptp->pin_dev_attr)
 		goto no_dev_attr;
 
-	ptp->pin_attr = kzalloc((1 + n_pins) * sizeof(struct attribute *),
-				GFP_KERNEL);
+	ptp->pin_attr = kcalloc(1 + n_pins, sizeof(*ptp->pin_attr), GFP_KERNEL);
 	if (!ptp->pin_attr)
 		goto no_pin_attr;
 
@@ -292,61 +298,18 @@ 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 device *dev = ptp->dev;
-	struct ptp_clock_info *info = ptp->info;
-	int err;
-
-	if (info->n_ext_ts) {
-		err = device_create_file(dev, &dev_attr_extts_enable);
-		if (err)
-			goto out1;
-		err = device_create_file(dev, &dev_attr_fifo);
-		if (err)
-			goto out2;
-	}
-	if (info->n_per_out) {
-		err = device_create_file(dev, &dev_attr_period);
-		if (err)
-			goto out3;
-	}
-	if (info->pps) {
-		err = device_create_file(dev, &dev_attr_pps_enable);
-		if (err)
-			goto out4;
-	}
-	if (info->n_pins) {
-		err = ptp_populate_pins(ptp);
-		if (err)
-			goto out5;
-	}
-	return 0;
-out5:
-	if (info->pps)
-		device_remove_file(dev, &dev_attr_pps_enable);
-out4:
-	if (info->n_per_out)
-		device_remove_file(dev, &dev_attr_period);
-out3:
-	if (info->n_ext_ts)
-		device_remove_file(dev, &dev_attr_fifo);
-out2:
-	if (info->n_ext_ts)
-		device_remove_file(dev, &dev_attr_extts_enable);
-out1:
-	return err;
+	kfree(ptp->pin_attr);
+	kfree(ptp->pin_dev_attr);
 }