[PATCH] hmm, handle net devices with udev?

Hmm, Arndt Bergmann sent a patch like this one a few weeks ago and
I want to bring the question back, if we want to handle net device
naming with udev.

With this patch it is actually possible to specify something like this
in udev.rules:

  KERNEL="dummy*", SYSFS{address}="00:00:00:00:00:00", SYSFS{features}="0x0", NAME="blind%n"
  KERNEL="eth*", SYSFS{address}="00:0d:60:77:30:91", NAME="private"

and you will get:

  [root@pim udev.kay]# cat /proc/net/dev
  Inter-|   Receive                                                | Transmit
   face |bytes    packets errs drop fifo frame compressed multicast|bytes   packets errs drop fifo colls carrier compressed
       lo:    1500     30    0    0    0     0          0         0    1500      30    0    0    0     0       0          0
  private:  278393   1114    0    0    0     0          0         0  153204    1468    0    0    0     0       0          0
     sit0:       0      0    0    0    0     0          0         0       0       0    0    0    0     0       0          0
   blind0:       0      0    0    0    0     0          0         0       0       0    0    0    0     0       0          0


The udevinfo program is also working:

  [root@pim udev.kay]# ./udevinfo -a -p /sys/class/net/private
    looking at class device '/sys/class/net/private':
      SYSFS{addr_len}="6"
      SYSFS{address}="00:0d:60:77:30:91"
      SYSFS{broadcast}="ff:ff:ff:ff:ff:ff"
      SYSFS{features}="0x3a9"
      SYSFS{flags}="0x1003"
      SYSFS{ifindex}="2"
      SYSFS{iflink}="2"
      SYSFS{mtu}="1500"
      SYSFS{tx_queue_len}="1000"
      SYSFS{type}="1"

  follow the class device's "device"
    looking at the device chain at '/sys/devices/pci0000:00/0000:00:1e.0/0000:02:01.0':
      BUS="pci"
      ID="0000:02:01.0"
      SYSFS{class}="0x020000"
      SYSFS{detach_state}="0"
      SYSFS{device}="0x101e"
      SYSFS{irq}="11"
      SYSFS{subsystem_device}="0x0549"
      SYSFS{subsystem_vendor}="0x1014"
      SYSFS{vendor}="0x8086"


The matching device will be renamed to the given name. The device name
will not be put into the udev database, cause the kernel renames the
device and the sysfs name disappears.

I like it, cause it plugs in nicely. We have all the naming features
and sysfs queries and walks inside of  udev. The sysfs timing races
are already solved and the management tools are working for net devices
too. nameif can only match the MAC address now. udev can match any sysfs
value of the device tree the net device is connected to.
But right, net devices do not have device nodes :)

1 files changed, 15 insertions, 9 deletions

diff --git a/udevinfo.c b/udevinfo.c
index 800882eb1a..b23f9d0aef 100644
--- a/udevinfo.c
+++ b/udevinfo.c
@@ -138,6 +138,10 @@ static int print_device_chain(const char *path)
 	struct sysfs_device *sysfs_dev;
 	struct sysfs_device *sysfs_dev_parent;
 	int retval = 0;
+	char type;
+
+	type = get_device_type(path, "");
+	dbg("device type is %c", type);
 
 	/*  get the class dev */
 	class_dev = sysfs_open_class_device_path(path);
@@ -146,21 +150,23 @@ static int print_device_chain(const char *path)
 		return -1;
 	}
 
-	/* read the 'dev' file for major/minor*/
-	attr = sysfs_get_classdev_attr(class_dev, "dev");
-	if (attr == NULL) {
-		printf("couldn't get the \"dev\" file\n");
-		retval = -1;
-		goto exit;
-	}
-
 	printf("\nudevinfo starts with the device the node belongs to and then walks up the\n"
 	       "device chain, to print for every device found, all possibly useful attributes\n"
 	       "in the udev key format.\n"
 	       "Only attributes within one device section may be used together in one rule,\n"
 	       "to match the device for which the node will be created.\n"
 	       "\n");
-	printf("device '%s' has major:minor %s", class_dev->path, attr->value);
+
+	if (type == 'b' || type =='c') {
+		/* read the 'dev' file for major/minor*/
+		attr = sysfs_get_classdev_attr(class_dev, "dev");
+		if (attr == NULL) {
+			printf("couldn't get the \"dev\" file\n");
+			retval = -1;
+			goto exit;
+		}
+		printf("device '%s' has major:minor %s", class_dev->path, attr->value);
+	}
 
 	/* open sysfs class device directory and print all attributes */
 	printf("  looking at class device '%s':\n", class_dev->path);