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udev/net_id: Introduce predictable network names for Linux on System z

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Use the bus-ID to create predicatable devices names for network interfaces
on Linux on System z instances.  The bus-ID identifies a device in the s390
channel subsystem.

Network interfaces of device type Ethernet are named as:
    enccw0.0.1234    (13 characters)
up to
    enccwff.7.ffff   (14 characters)

CTC network devices of device type SLIP, use a different prefix as follows:
    slccw0.0.1234    (13 characters)

See also Red Hat Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=870859
[tomegun: typical problem of netdevs switching names between reboots.]
This commit is contained in:
Hendrik Brueckner 2014-01-09 11:28:12 +01:00 committed by Tom Gundersen
parent 2a61aaac66
commit e0d4a0ac06
1 changed files with 62 additions and 2 deletions
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64
src/udev/udev-builtin-net_id.c
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@ -28,6 +28,7 @@
*
* Two character prefixes based on the type of interface:
* en -- ethernet
* sl -- serial line IP (slip)
* wl -- wlan
* ww -- wwan
*
@ -102,6 +103,7 @@ enum netname_type{
NET_USB,
NET_BCMA,
NET_VIRTIO,
NET_CCWGROUP,
};
struct netnames {
@ -121,6 +123,8 @@ struct netnames {
char bcma_core[IFNAMSIZ];
char virtio_core[IFNAMSIZ];
char ccw_core[IFNAMSIZ];
};
/* retrieve on-board index number and label from firmware */
@ -366,6 +370,44 @@ static int names_virtio(struct udev_device *dev, struct netnames *names) {
return 0;
}
static int names_ccw(struct udev_device *dev, struct netnames *names) {
struct udev_device *cdev;
const char *bus_id;
size_t bus_id_len;
int rc;
/* Retrieve the associated CCW device */
cdev = udev_device_get_parent(dev);
if (!cdev)
return -ENOENT;
/* Network devices are always grouped CCW devices */
if (!streq_ptr("ccwgroup", udev_device_get_subsystem(cdev)))
return -ENOENT;
/* Retrieve bus-ID of the grouped CCW device. The bus-ID uniquely
* identifies the network device on the Linux on System z channel
* subsystem. Note that the bus-ID contains lowercase characters.
*/
bus_id = udev_device_get_sysname(cdev);
if (!bus_id)
return -ENOENT;
/* Check the length of the bus-ID. Rely on that the kernel provides
* a correct bus-ID; alternatively, improve this check and parse and
* verify each bus-ID part...
*/
bus_id_len = strlen(bus_id);
if (!bus_id_len || bus_id_len < 8 || bus_id_len > 9)
return -EINVAL;
/* Store the CCW bus-ID for use as network device name */
rc = snprintf(names->ccw_core, sizeof(names->ccw_core), "ccw%s", bus_id);
if (rc >= 0 && rc < (int)sizeof(names->ccw_core))
names->type = NET_CCWGROUP;
return 0;
}
static int names_mac(struct udev_device *dev, struct netnames *names) {
const char *s;
unsigned int i;
@ -424,13 +466,21 @@ static int builtin_net_id(struct udev_device *dev, int argc, char *argv[], bool
struct netnames names = {};
int err;
/* handle only ARPHRD_ETHER devices */
/* handle only ARPHRD_ETHER and ARPHRD_SLIP devices */
s = udev_device_get_sysattr_value(dev, "type");
if (!s)
return EXIT_FAILURE;
i = strtoul(s, NULL, 0);
if (i != 1)
switch (i) {
case 1: /* ARPHRD_ETHER */
prefix = "en";
break;
case 256: /* ARPHRD_SLIP */
prefix = "sl";
break;
default:
return 0;
}
/* skip stacked devices, like VLANs, ... */
s = udev_device_get_sysattr_value(dev, "ifindex");
@ -462,6 +512,16 @@ static int builtin_net_id(struct udev_device *dev, int argc, char *argv[], bool
ieee_oui(dev, &names, test);
}
/* get path names for Linux on System z network devices */
err = names_ccw(dev, &names);
if (err >= 0 && names.type == NET_CCWGROUP) {
char str[IFNAMSIZ];
if (snprintf(str, sizeof(str), "%s%s", prefix, names.ccw_core) < (int)sizeof(str))
udev_builtin_add_property(dev, test, "ID_NET_NAME_PATH", str);
goto out;
}
/* get PCI based path names, we compose only PCI based paths */
err = names_pci(dev, &names);
if (err < 0)