[RFC v5 1/3] workqueue: Simplify unbound sysfs attribute registration

[Tvrtko Ursulin]

Instead of manually registering each attribute we can put them in an
attribute group with a visibility check and device core will handle the
rest, which simplifies the registration and error unwind.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Cc: Bradley Morgan <include@xxxxxxxxx>
Cc: Chia-I Wu <olv@xxxxxxxxxx>
Cc: Liviu Dudau <liviu.dudau@xxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
 kernel/workqueue.c | 98 ++++++++++++++++++++++++----------------------
 1 file changed, 52 insertions(+), 46 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e618108c6127..e3a4ad56dae8 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -7599,8 +7599,8 @@ static const struct attribute_group wq_sysfs_group = {
 };
 __ATTRIBUTE_GROUPS(wq_sysfs);
 
-static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
-			    char *buf)
+static ssize_t nice_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	int written;
@@ -7627,8 +7627,8 @@ static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
 	return attrs;
 }
 
-static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
-			     const char *buf, size_t count)
+static ssize_t nice_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t count)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	struct workqueue_attrs *attrs;
@@ -7652,8 +7652,8 @@ static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
 	return ret ?: count;
 }
 
-static ssize_t wq_cpumask_show(struct device *dev,
-			       struct device_attribute *attr, char *buf)
+static ssize_t unbound_cpumask_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	int written;
@@ -7665,9 +7665,9 @@ static ssize_t wq_cpumask_show(struct device *dev,
 	return written;
 }
 
-static ssize_t wq_cpumask_store(struct device *dev,
-				struct device_attribute *attr,
-				const char *buf, size_t count)
+static ssize_t unbound_cpumask_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	struct workqueue_attrs *attrs;
@@ -7689,8 +7689,8 @@ static ssize_t wq_cpumask_store(struct device *dev,
 	return ret ?: count;
 }
 
-static ssize_t wq_affn_scope_show(struct device *dev,
-				  struct device_attribute *attr, char *buf)
+static ssize_t affn_scope_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	int written;
@@ -7708,9 +7708,9 @@ static ssize_t wq_affn_scope_show(struct device *dev,
 	return written;
 }
 
-static ssize_t wq_affn_scope_store(struct device *dev,
-				   struct device_attribute *attr,
-				   const char *buf, size_t count)
+static ssize_t affn_scope_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	struct workqueue_attrs *attrs;
@@ -7731,8 +7731,8 @@ static ssize_t wq_affn_scope_store(struct device *dev,
 	return ret ?: count;
 }
 
-static ssize_t wq_affinity_strict_show(struct device *dev,
-				       struct device_attribute *attr, char *buf)
+static ssize_t affinity_strict_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 
@@ -7740,9 +7740,9 @@ static ssize_t wq_affinity_strict_show(struct device *dev,
 			 wq->attrs->affn_strict);
 }
 
-static ssize_t wq_affinity_strict_store(struct device *dev,
-					struct device_attribute *attr,
-					const char *buf, size_t count)
+static ssize_t affinity_strict_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
 {
 	struct workqueue_struct *wq = dev_to_wq(dev);
 	struct workqueue_attrs *attrs;
@@ -7762,14 +7762,40 @@ static ssize_t wq_affinity_strict_store(struct device *dev,
 	return ret ?: count;
 }
 
-static struct device_attribute wq_sysfs_unbound_attrs[] = {
-	__ATTR(nice, 0644, wq_nice_show, wq_nice_store),
-	__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
-	__ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store),
-	__ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store),
-	__ATTR_NULL,
+static DEVICE_ATTR_RW(nice);
+static DEVICE_ATTR_RW(affn_scope);
+static DEVICE_ATTR_RW(affinity_strict);
+/* Avoid naming clash with the other cpumask */
+static struct device_attribute dev_attr_unbound_cpumask =
+	__ATTR(cpumask, 0644, unbound_cpumask_show, unbound_cpumask_store);
+
+static struct attribute *wq_sysfs_unbound_attrs[] = {
+	&dev_attr_nice.attr,
+	&dev_attr_unbound_cpumask.attr,
+	&dev_attr_affn_scope.attr,
+	&dev_attr_affinity_strict.attr,
+	NULL,
 };
 
+static umode_t wq_sysfs_unbound_group_visible(struct kobject *kobj,
+					      struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct workqueue_struct *wq = dev_to_wq(dev);
+
+	if (!(wq->flags & WQ_UNBOUND))
+		return SYSFS_GROUP_INVISIBLE;
+
+	return attr->mode;
+}
+
+static const struct attribute_group wq_sysfs_unbound_group = {
+	.is_visible = wq_sysfs_unbound_group_visible,
+	.attrs = wq_sysfs_unbound_attrs,
+};
+
+__ATTRIBUTE_GROUPS(wq_sysfs_unbound);
+
 static const struct bus_type wq_subsys = {
 	.name				= "workqueue",
 	.dev_groups			= wq_sysfs_groups,
@@ -7907,14 +7933,9 @@ int workqueue_sysfs_register(struct workqueue_struct *wq)
 	wq_dev->wq = wq;
 	wq_dev->dev.bus = &wq_subsys;
 	wq_dev->dev.release = wq_device_release;
+	wq_dev->dev.groups = wq_sysfs_unbound_groups;
 	dev_set_name(&wq_dev->dev, "%s", wq->name);
 
-	/*
-	 * attrs are created separately.  Suppress uevent until
-	 * everything is ready.
-	 */
-	dev_set_uevent_suppress(&wq_dev->dev, true);
-
 	ret = device_register(&wq_dev->dev);
 	if (ret) {
 		put_device(&wq_dev->dev);
@@ -7922,21 +7943,6 @@ int workqueue_sysfs_register(struct workqueue_struct *wq)
 		return ret;
 	}
 
-	if (wq->flags & WQ_UNBOUND) {
-		struct device_attribute *attr;
-
-		for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
-			ret = device_create_file(&wq_dev->dev, attr);
-			if (ret) {
-				device_unregister(&wq_dev->dev);
-				wq->wq_dev = NULL;
-				return ret;
-			}
-		}
-	}
-
-	dev_set_uevent_suppress(&wq_dev->dev, false);
-	kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
 	return 0;
 }
 
-- 
2.55.0