Message ID | 1405348645-1995-1-git-send-email-teg@jklm.no |
---|---|
State | Accepted, archived |
Delegated to: | David Miller |
Headers | show |
From: Tom Gundersen <teg@jklm.no> Date: Mon, 14 Jul 2014 16:37:22 +0200 > Based on a patch by David Herrmann. > > The name_assign_type attribute gives hints where the interface name of a > given net-device comes from. These values are currently defined: ... > The aim of these patches is to improve user-space renaming of interfaces. As > a general rule, userspace must rename interfaces to guarantee that names stay > the same every time a given piece of hardware appears (at boot, or when > attaching it). However, there are several situations where userspace should > not perform the renaming, and that depends on both the policy of the local > admin, but crucially also on the nature of the current interface name. > > If an interface was created in repsonse to a userspace request, and userspace > already provided a name, we most probably want to leave that name alone. The > main instance of this is wifi-P2P devices created over nl80211, which currently > have a long-standing bug where they are getting renamed by udev. We label such > names NET_NAME_USER. > > If an interface, unbeknown to us, has already been renamed from userspace, we > most probably want to leave also that alone. This will typically happen when > third-party plugins (for instance to udev, but the interface is generic so could > be from anywhere) renames the interface without informing udev about it. A > typical situation is when you switch root from an installer or an initrd to the > real system and the new instance of udev does not know what happened before > the switch. These types of problems have caused repeated issues in the past. To > solve this, once an interface has been renamed, its name is labelled > NET_NAME_RENAMED. > > In many cases, the kernel is actually able to name interfaces in such a > way that there is no need for userspace to rename them. This is the case when > the enumeration order of devices, or in fact any other (non-parent) device on > the system, can not influence the name of the interface. Examples include > statically created devices, or any naming schemes based on hardware properties > of the interface. In this case the admin may prefer to use the kernel-provided > names, and to make that possible we label such names NET_NAME_PREDICTABLE. > We want the kernel to have tho possibilty of performing predictable interface > naming itself (and exposing to userspace that it has), as the information > necessary for a proper naming scheme for a certain class of devices may not > be exposed to userspace. > > The case where renaming is almost certainly desired, is when the kernel has > given the interface a name using global device enumeration based on order of > discovery (ethX, wlanY, etc). These naming schemes are labelled NET_NAME_ENUM. > > Lastly, a fallback is left as NET_NAME_UNKNOWN, to indicate that a driver has > not yet been ported. This is mostly useful as a transitionary measure, allowing > us to label the various naming schemes bit by bit. > > v8: minor documentation fixes > v9: move comment to the right commit > > Signed-off-by: Tom Gundersen <teg@jklm.no> > Reviewed-by: David Herrmann <dh.herrmann@gmail.com> > Reviewed-by: Kay Sievers <kay@vrfy.org> Applied. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net index 416c5d5..d322b05 100644 --- a/Documentation/ABI/testing/sysfs-class-net +++ b/Documentation/ABI/testing/sysfs-class-net @@ -1,3 +1,14 @@ +What: /sys/class/net/<iface>/name_assign_type +Date: July 2014 +KernelVersion: 3.17 +Contact: netdev@vger.kernel.org +Description: + Indicates the name assignment type. Possible values are: + 1: enumerated by the kernel, possibly in an unpredictable way + 2: predictably named by the kernel + 3: named by userspace + 4: renamed + What: /sys/class/net/<iface>/addr_assign_type Date: July 2010 KernelVersion: 3.2 diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 66f9a04..551e187 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1379,6 +1379,8 @@ struct net_device { struct kset *queues_kset; #endif + unsigned char name_assign_type; + bool uc_promisc; unsigned int promiscuity; unsigned int allmulti; diff --git a/include/uapi/linux/netdevice.h b/include/uapi/linux/netdevice.h index fdfbd1c..5581854 100644 --- a/include/uapi/linux/netdevice.h +++ b/include/uapi/linux/netdevice.h @@ -37,6 +37,12 @@ #define INIT_NETDEV_GROUP 0 +/* interface name assignment types (sysfs name_assign_type attribute) */ +#define NET_NAME_UNKNOWN 0 /* unknown origin (not exposed to userspace) */ +#define NET_NAME_ENUM 1 /* enumerated by kernel */ +#define NET_NAME_PREDICTABLE 2 /* predictably named by the kernel */ +#define NET_NAME_USER 3 /* provided by user-space */ +#define NET_NAME_RENAMED 4 /* renamed by user-space */ /* Media selection options. */ enum { diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 1cac29e..7752f2a 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -112,6 +112,25 @@ NETDEVICE_SHOW_RO(ifindex, fmt_dec); NETDEVICE_SHOW_RO(type, fmt_dec); NETDEVICE_SHOW_RO(link_mode, fmt_dec); +static ssize_t format_name_assign_type(const struct net_device *net, char *buf) +{ + return sprintf(buf, fmt_dec, net->name_assign_type); +} + +static ssize_t name_assign_type_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct net_device *net = to_net_dev(dev); + ssize_t ret = -EINVAL; + + if (net->name_assign_type != NET_NAME_UNKNOWN) + ret = netdev_show(dev, attr, buf, format_name_assign_type); + + return ret; +} +static DEVICE_ATTR_RO(name_assign_type); + /* use same locking rules as GIFHWADDR ioctl's */ static ssize_t address_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -387,6 +406,7 @@ static struct attribute *net_class_attrs[] = { &dev_attr_dev_port.attr, &dev_attr_iflink.attr, &dev_attr_ifindex.attr, + &dev_attr_name_assign_type.attr, &dev_attr_addr_assign_type.attr, &dev_attr_addr_len.attr, &dev_attr_link_mode.attr,