[PATCH] add IGNORE rule type

On Wed, Dec 31, 2003 at 11:24:53AM -0800, Greg KH wrote:

> > There should be a possibility to tell udev not to create a device node.
> >
> > device-mapper: Usually set up by libdevmapper (or EVMS tools) which
> > creates the device node on its own under /dev/mapper/<name>.
> >
> > With udev a second device is created named /dev/dm-<minor> which is not
> > really needed.
>
> Good point.  Ok, I'll agree with you.  Care to make up a patch for this
> kind of feature?

Yes, I can try.

There was no way to tell not to do anything so I created one. Errors
are signalled via negative return values, so I thought that a positive,
non-zero one could mean to ignore the device. I don't like it but
perhaps you have a better solution.

etc/udev/udev.rules

@@ -49,4 +49,5 @@ REPLACE, KERNEL="ttyUSB0", NAME="pl2303"
 # if this is a ide cdrom, name it the default name, and create a symlink to cdrom
 CALLOUT, BUS="ide", PROGRAM="/bin/cat /proc/ide/%k/media", ID="cdrom", NAME="%k", SYMLINK="cdrom" 
 
-
+# device mapper creates its own device nodes
+IGNORE, KERNEL="dm-[0-9]*"

etc/udev/udev.rules.devfs

@@ -41,3 +41,6 @@ REPLACE, KERNEL="video[0-9]*", NAME="v4l/video%n"
 REPLACE, KERNEL="radio[0-9]*", NAME="v4l/radio%n"
 REPLACE, KERNEL="vbi[0-9]*",   NAME="v4l/vbi%n"
 REPLACE, KERNEL="vtx[0-9]*",   NAME="v4l/vtx%n"
+
+# dm devices
+IGNORE, KERNEL="dm-[0-9]*"

namedev.c

@@ -298,6 +298,27 @@ exit:
 	return; /* here to prevent compiler warning... */
 }
 
+static int do_ignore(struct sysfs_class_device *class_dev, struct udevice *udev, struct sysfs_device *sysfs_device)
+{
+	struct config_device *dev;
+	struct list_head *tmp;
+
+	list_for_each(tmp, &config_device_list) {
+		dev = list_entry(tmp, struct config_device, node);
+		if (dev->type != IGNORE)
+			continue;
+
+		dbg("compare name '%s' with '%s'", dev->kernel_name, class_dev->name);
+		if (strcmp_pattern(dev->kernel_name, class_dev->name) != 0)
+			continue;
+
+		dbg("found name, '%s' will be ignored", dev->kernel_name);
+
+		return 0;
+	}
+	return -ENODEV;
+}
+
 static int exec_callout(struct config_device *dev, char *value, int len)
 {
 	int retval;
@@ -734,6 +755,12 @@ int namedev_name_device(struct sysfs_class_device *class_dev, struct udevice *ud
 	dbg("kernel_number='%s'", udev->kernel_number);
 
 	/* rules are looked at in priority order */
+	retval = do_ignore(class_dev, udev, sysfs_device);
+	if (retval == 0) {
+		dbg("name, '%s' is being ignored", class_dev->name);
+		return 1;
+	}
+
 	retval = do_callout(class_dev, udev, sysfs_device);
 	if (retval == 0)
 		goto found;

namedev.h

@@ -36,6 +36,7 @@ enum config_type {
 	TOPOLOGY	= 3,
 	REPLACE		= 4,
 	CALLOUT		= 5,
+	IGNORE		= 6,
 };
 
 #define BUS_SIZE	30
@@ -50,6 +51,7 @@ enum config_type {
 #define TYPE_TOPOLOGY	"TOPOLOGY"
 #define TYPE_REPLACE	"REPLACE"
 #define TYPE_CALLOUT	"CALLOUT"
+#define TYPE_IGNORE	"IGNORE"
 
 #define FIELD_BUS	"BUS"
 #define FIELD_ID	"ID"

namedev_parse.c

@@ -110,6 +110,10 @@ void dump_config_dev(struct config_device *dev)
 		dbg_parse("CALLOUT name='%s', bus='%s', program='%s', id='%s'",
 			  dev->name, dev->bus, dev->exec_program, dev->id);
 		break;
+	case IGNORE:
+		dbg_parse("IGNORE name='%s', kernel_name='%s'",
+			  dev->name, dev->kernel_name);
+		break;
 	default:
 		dbg_parse("unknown type of method");
 	}
@@ -209,6 +213,11 @@ int namedev_init_rules(void)
 			goto keys;
 		}
 
+		if (strcasecmp(temp2, TYPE_IGNORE) == 0) {
+			dev.type = IGNORE;
+			goto keys;
+		}
+
 		dbg_parse("unknown type of method '%s'", temp2);
 		goto error;
 keys:
@@ -323,6 +332,12 @@ keys:
 			    (*dev.exec_program == '\0'))
 				goto error;
 			break;
+		case IGNORE:
+			dbg_parse(TYPE_IGNORE "name='%s', kernel_name='%s'",
+				  dev.name, dev.kernel_name);
+			if ((*dev.kernel_name == '\0'))
+				goto error;
+			break;
 		default:
 			dbg_parse("unknown type of method");
 			goto error;

udev.8

@@ -161,9 +161,15 @@ device position on bus, like physical port of USB device
 string replacement of the kernel device name
 .br
 .RB "key: " KERNEL
+.TP
+.B IGNORE
+tell udev to not care about creation of this device, e.g. because the
+device is already handled by another program
+.br
+.RB "key: " KERNEL
 .P
 The methods are applied in the following order:
-.BR CALLOUT ", " LABEL ", " NUMBER ", " TOPOLOGY ", " REPLACE "."
+.BR IGNORE ", " CALLOUT ", " LABEL ", " NUMBER ", " TOPOLOGY ", " REPLACE "."
 .P
 .RB "The " NAME " ," SYMLINK " and " PROGRAM
 fields support simple printf-like string substitution:

udev.c

@@ -221,6 +221,9 @@ exit_sysbus:
 	sysbus_disconnect();
 
 exit:
+	if (retval > 0)
+		retval = 0;
+
 	return -retval;
 }