Re: [PATCH] USB and Driver Core patches for 2.6.10

[Greg KH <greg@kroah.com>]

ChangeSet 1.1938.444.1, 2004/12/15 10:48:19-08:00, rml@novell.com

[PATCH] add class_device to miscdevice

Currently misc_register() throws away the return from
class_simple_device_add().  This makes it impossible to get to the
class_device of the directories in /sys/class/misc and, for example,
thus impossible to add attributes to those directories.

Attached patch adds a class_device structure to the miscdevice structure
and assigns to it the value returned from class_simple_device_add() in
misc_register(), thus caching the value and allowing us to f.e. later
call class_device_create_file().

We need this for inotify, but I can see plenty of other misc. devices
wanting this and consider it missing but required functionality.


Add the class_device structure to miscdevice so that we can add sysfs
attributes to /sys/class/misc/foo

Signed-Off-By: Robert Love <rml@novell.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>


 drivers/char/misc.c        |   14 ++++++--------
 include/linux/miscdevice.h |    5 +++--
 2 files changed, 9 insertions(+), 10 deletions(-)


diff -Nru a/drivers/char/misc.c b/drivers/char/misc.c
--- a/drivers/char/misc.c	2005-01-07 15:52:07 -08:00
+++ b/drivers/char/misc.c	2005-01-07 15:52:07 -08:00
@@ -207,10 +207,9 @@
 int misc_register(struct miscdevice * misc)
 {
 	struct miscdevice *c;
-	struct class_device *class;
 	dev_t dev;
 	int err;
-	
+
 	down(&misc_sem);
 	list_for_each_entry(c, &misc_list, list) {
 		if (c->minor == misc->minor) {
@@ -224,8 +223,7 @@
 		while (--i >= 0)
 			if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
 				break;
-		if (i<0)
-		{
+		if (i<0) {
 			up(&misc_sem);
 			return -EBUSY;
 		}
@@ -240,10 +238,10 @@
 	}
 	dev = MKDEV(MISC_MAJOR, misc->minor);
 
-	class = class_simple_device_add(misc_class, dev,
-					misc->dev, misc->name);
-	if (IS_ERR(class)) {
-		err = PTR_ERR(class);
+	misc->class = class_simple_device_add(misc_class, dev,
+					      misc->dev, misc->name);
+	if (IS_ERR(misc->class)) {
+		err = PTR_ERR(misc->class);
 		goto out;
 	}
 
diff -Nru a/include/linux/miscdevice.h b/include/linux/miscdevice.h
--- a/include/linux/miscdevice.h	2005-01-07 15:52:07 -08:00
+++ b/include/linux/miscdevice.h	2005-01-07 15:52:07 -08:00
@@ -2,6 +2,7 @@
 #define _LINUX_MISCDEVICE_H
 #include <linux/module.h>
 #include <linux/major.h>
+#include <linux/device.h>
 
 #define PSMOUSE_MINOR  1
 #define MS_BUSMOUSE_MINOR 2
@@ -32,13 +33,13 @@
 
 struct device;
 
-struct miscdevice 
-{
+struct miscdevice  {
 	int minor;
 	const char *name;
 	struct file_operations *fops;
 	struct list_head list;
 	struct device *dev;
+	struct class_device *class;
 	char devfs_name[64];
 };