coldplug - emit hotplug events from sysfs

RFC In review Kay Sievers 7 participants 17 messages Oct 1, 2005 – Oct 29, 2005

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Kay Sievers

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2005-10-01 12:49 UTC #0 lore raw

RFC 1/1 coldplug - emit hotplug events from sysfs

Here is another approach to address the coldplug problem. After playing around with "udevsythesize" it felt stupid to try to compose all the events from sysfs values which will never be exactly the same as the kernel event.
This patch adds a "uevent" file to all class/block/bus-devices. Writing to this file, will just emit the hotplug event from the kernel again. udevstart and all the coldplug logic can be 3 lines of shell-script now. Boots fine and is _very_ fast on my box.

What do you think?

Thanks,
Kay

------------
From: Kay Sievers <[email protected]>
Subject: add sysfs attr to re-emit device hotplug event

A "coldplug + udevstart" can be simple like this:
for i in /sys/block/*/*/uevent; do echo 1 > $i; done for i in /sys/class/*/*/uevent; do echo 1 > $i; done for i in /sys/bus/*/devices/*/uevent; do echo 1 > $i; done

Signed-off-by Kay Sievers <[email protected]>

---

drivers/base/class.c +14 -2

@@ -442,6 +442,13 @@ static ssize_t show_dev(struct class_dev
 	return print_dev_t(buf, class_dev->devt);
 }
 
+static ssize_t store_uevent(struct class_device *class_dev,
+			    const char *buf, size_t count)
+{
+	kobject_hotplug(&class_dev->kobj, KOBJ_ADD);
+	return count;
+}
+
 void class_device_initialize(struct class_device *class_dev)
 {
 	kobj_set_kset_s(class_dev, class_obj_subsys);

@@ -497,6 +504,12 @@ int class_device_add(struct class_device
 		goto register_done;
 
 	/* add the needed attributes to this device */
+	class_dev->uevent_attr.attr.name = "uevent";
+	class_dev->uevent_attr.attr.mode = S_IWUSR;
+	class_dev->uevent_attr.attr.owner = parent->owner;
+	class_dev->uevent_attr.store = store_uevent;
+	class_device_create_file(class_dev, &class_dev->uevent_attr);
+
 	if (MAJOR(class_dev->devt)) {
 		struct class_device_attribute *attr;
 		attr = kzalloc(sizeof(*attr), GFP_KERNEL);

@@ -505,12 +518,10 @@ int class_device_add(struct class_device
 			kobject_del(&class_dev->kobj);
 			goto register_done;
 		}
-
 		attr->attr.name = "dev";
 		attr->attr.mode = S_IRUGO;
 		attr->attr.owner = parent->owner;
 		attr->show = show_dev;
-		attr->store = NULL;
 		class_device_create_file(class_dev, attr);
 		class_dev->devt_attr = attr;
 	}

@@ -620,6 +631,7 @@ void class_device_del(struct class_devic
 		sysfs_remove_link(&class_dev->kobj, "device");
 		sysfs_remove_link(&class_dev->dev->kobj, class_name);
 	}
+	class_device_remove_file(class_dev, &class_dev->uevent_attr);
 	if (class_dev->devt_attr)
 		class_device_remove_file(class_dev, class_dev->devt_attr);
 	class_device_remove_attrs(class_dev);

drivers/base/core.c +16 -0

@@ -154,6 +154,13 @@ static struct kset_hotplug_ops device_ho
 	.hotplug =	dev_hotplug,
 };
 
+static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	kobject_hotplug(&dev->kobj, KOBJ_ADD);
+	return count;
+}
+
 /**
  *	device_subsys - structure to be registered with kobject core.
  */

@@ -258,6 +265,14 @@ int device_add(struct device *dev)
 
 	if ((error = kobject_add(&dev->kobj)))
 		goto Error;
+
+	dev->uevent_attr.attr.name = "uevent";
+	dev->uevent_attr.attr.mode = S_IWUSR;
+	if (dev->driver)
+		dev->uevent_attr.attr.owner = dev->driver->owner;
+	dev->uevent_attr.store = store_uevent;
+	device_create_file(dev, &dev->uevent_attr);
+
 	kobject_hotplug(&dev->kobj, KOBJ_ADD);
 	if ((error = device_pm_add(dev)))
 		goto PMError;

@@ -349,6 +364,7 @@ void device_del(struct device * dev)
 
 	if (parent)
 		klist_del(&dev->knode_parent);
+	device_remove_file(dev, &dev->uevent_attr);
 
 	/* Notify the platform of the removal, in case they
 	 * need to do anything...

drivers/block/genhd.c +24 -0

@@ -337,10 +337,30 @@ static ssize_t disk_attr_show(struct kob
 	return ret;
 }
 
+static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
+			       const char *page, size_t count)
+{
+	struct gendisk *disk = to_disk(kobj);
+	struct disk_attribute *disk_attr +		container_of(attr,struct disk_attribute,attr);
+	ssize_t ret = 0;
+
+	if (disk_attr->store)
+		ret = disk_attr->store(disk, page, count);
+	return ret;
+}
+
 static struct sysfs_ops disk_sysfs_ops = {
 	.show	= &disk_attr_show,
+	.store	= &disk_attr_store,
 };
 
+static ssize_t disk_uevent_store(struct gendisk * disk,
+				 const char *buf, size_t count)
+{
+	kobject_hotplug(&disk->kobj, KOBJ_ADD);
+	return count;
+}
 static ssize_t disk_dev_read(struct gendisk * disk, char *page)
 {
 	dev_t base = MKDEV(disk->major, disk->first_minor);

@@ -382,6 +402,10 @@ static ssize_t disk_stats_read(struct ge
 		jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
 		jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
 }
+static struct disk_attribute disk_attr_uevent = {
+	.attr = {.name = "uevent", .mode = S_IWUSR },
+	.store	= disk_uevent_store
+};
 static struct disk_attribute disk_attr_dev = {
 	.attr = {.name = "dev", .mode = S_IRUGO },
 	.show	= disk_dev_read

@@ -404,6 +428,7 @@ static struct disk_attribute disk_attr_s
 };
 
 static struct attribute * default_attrs[] = {
+	&disk_attr_uevent.attr,
 	&disk_attr_dev.attr,
 	&disk_attr_range.attr,
 	&disk_attr_removable.attr,

fs/partitions/check.c +26 -1

@@ -192,6 +192,7 @@ check_partition(struct gendisk *hd, stru
 struct part_attribute {
 	struct attribute attr;
 	ssize_t (*show)(struct hd_struct *,char *);
+	ssize_t (*store)(struct hd_struct *,const char *, size_t);
 };
 
 static ssize_t

@@ -201,14 +202,33 @@ part_attr_show(struct kobject * kobj, st
 	struct part_attribute * part_attr = container_of(attr,struct part_attribute,attr);
 	ssize_t ret = 0;
 	if (part_attr->show)
-		ret = part_attr->show(p,page);
+		ret = part_attr->show(p, page);
+	return ret;
+}
+static ssize_t
+part_attr_store(struct kobject * kobj, struct attribute * attr,
+		const char *page, size_t count)
+{
+	struct hd_struct * p = container_of(kobj,struct hd_struct,kobj);
+	struct part_attribute * part_attr = container_of(attr,struct part_attribute,attr);
+	ssize_t ret = 0;
+
+	if (part_attr->store)
+		ret = part_attr->store(p, page, count);
 	return ret;
 }
 
 static struct sysfs_ops part_sysfs_ops = {
 	.show	=	part_attr_show,
+	.store	=	part_attr_store,
 };
 
+static ssize_t part_uevent_store(struct hd_struct * p,
+				 const char *page, size_t count)
+{
+	kobject_hotplug(&p->kobj, KOBJ_ADD);
+	return count;
+}
 static ssize_t part_dev_read(struct hd_struct * p, char *page)
 {
 	struct gendisk *disk = container_of(p->kobj.parent,struct gendisk,kobj);

@@ -229,6 +249,10 @@ static ssize_t part_stat_read(struct hd_
 		       p->reads, (unsigned long long)p->read_sectors,
 		       p->writes, (unsigned long long)p->write_sectors);
 }
+static struct part_attribute part_attr_uevent = {
+	.attr = {.name = "uevent", .mode = S_IWUSR },
+	.store	= part_uevent_store
+};
 static struct part_attribute part_attr_dev = {
 	.attr = {.name = "dev", .mode = S_IRUGO },
 	.show	= part_dev_read

@@ -247,6 +271,7 @@ static struct part_attribute part_attr_s
 };
 
 static struct attribute * default_attrs[] = {
+	&part_attr_uevent.attr,
 	&part_attr_dev.attr,
 	&part_attr_start.attr,
 	&part_attr_size.attr,

include/linux/device.h +28 ~~-29~~

93 lines not on this page · raw message

include/linux/genhd.h +1 -0

@@ -132,6 +132,7 @@ struct gendisk {
 struct disk_attribute {
 	struct attribute attr;
 	ssize_t (*show)(struct gendisk *, char *);
+	ssize_t (*store)(struct gendisk *, const char *, size_t);
 };
 
 /*

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Scott James Remnant

2005-10-03 10:03 UTC #1 lore raw

Quoted 7 lines · Kay Sievers

This patch adds a "uevent" file to all class/block/bus-devices. Writing to this file, will just emit the hotplug event from the kernel again. udevstart and all the coldplug logic can be 3 lines of shell-script now. Boots fine and is _very_ fast on my box.
What do you think?

Cute :) Seems like a much more efficient way of doing it, just use the kernel's own code again.

Scott

Signature · 2 lines

Scott James Remnant
[email protected]

Olivier Blin

2005-10-03 10:29 UTC #2 lore raw