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udevHandleOneDevice: Remove old instance of device on "move"

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When a device is "move"-d (this basically means it was renamed),
we add the new device onto our list but keep the old there too.
Fortunately, udev sets this DEVPATH_OLD property which points to
the old device path. We can use it to remove the old instance.

To test this try renaming an interface, for instance:

  # ip link set tunl0 name tunl1
  # ip link set tunl1 name tunl0

One problem with udev is that it sends old ifname in INTERFACE
property, which creates a problem for us, the property is where
we get the ifname from and use it then to query all kind of info
about the interface. Well, if it is non-existent then we can't
query anything. This happens if ifname rename is suppressed
(net.ifnames=0 on kernel cmd line for instance). Fortunately, we
can use "kernel" source for udev events which has always the
fresh info.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
This commit is contained in:
Michal Privoznik 2020-04-20 16:12:03 +02:00
parent bfa8cf4b29
commit 9a13704818
1 changed files with 9 additions and 2 deletions
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11
src/node_device/node_device_udev.c
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@ -1507,7 +1507,14 @@ udevHandleOneDevice(struct udev_device *device)
return udevRemoveOneDevice(device);
if (STREQ(action, "move")) {
/* TODO: implement a way of finding and removing the old device */
const char *devpath_old = udevGetDeviceProperty(device, "DEVPATH_OLD");
if (devpath_old) {
g_autofree char *devpath_old_fixed = g_strdup_printf("/sys%s", devpath_old);
udevRemoveOneDeviceSysPath(devpath_old_fixed);
}
return udevAddOneDevice(device);
}
@ -1872,7 +1879,7 @@ nodeStateInitialize(bool privileged,
virObjectLock(priv);
priv->udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
priv->udev_monitor = udev_monitor_new_from_netlink(udev, "kernel");
if (!priv->udev_monitor) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("udev_monitor_new_from_netlink returned NULL"));