[PATCH 1/4] net: add name_assign_type netdev attribute
From: David Herrmann <hidden>
Date: 2014-02-27 14:47:35
Also in:
linux-wireless, lkml
Subsystem:
networking drivers, networking [general], the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The name_assign_type attribute gives hints where the interface name of a
given net-device comes from. Three different values are currently defined:
NET_NAME_ENUM:
This is the default. The ifname is provided by the kernel with an
enumerated suffix. Names may be reused and unstable.
NET_NAME_USER:
The ifname was provided by user-space during net-device setup.
NET_NAME_RENAMED:
The net-device has been renamed via RTNL. Once this type is set, it
cannot change again.
This attribute comes in handy for reliable net-device names. If an ifname
is provided by user-space, we can safely assume that the naming-policy
avoids reuse and is stable. Only if it was set by the kernel, the
interfaces might need to be renamed.
The NET_NAME_RENAMED value allows us to detect whether some-one else
already renamed the device, in which case we shouldn't touch it again. The
NET_NAME_USER value allows us to detect whether some other naming policy
created the device, in which case there's no need to rename it.
The most significant use-case is to detect virtual wifi-P2P devices, which
are named by wpa_supplicant et al. We shouldn't rename them as wpas
already provides a proper naming-policy.
Note that this patch only provides the core infrastructure. The different
net-dev types need to be manually fixed to use NET_NAME_USER instead of
the default (NET_NAME_ENUM). NET_NAME_ENUM is the least restrictive,
though, so it seems safe to use it as fallback for non-converted net-dev
types.
Signed-off-by: David Herrmann <redacted>
---
include/linux/netdevice.h | 6 ++++++
net/core/dev.c | 7 +++++++
net/core/net-sysfs.c | 2 ++
net/core/rtnetlink.c | 2 ++
4 files changed, 17 insertions(+)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e8eeebd..d3a11c8 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h@@ -74,6 +74,11 @@ void netdev_set_default_ethtool_ops(struct net_device *dev, #define NET_RX_SUCCESS 0 /* keep 'em coming, baby */ #define NET_RX_DROP 1 /* packet dropped */ +/* interface name assignment types */ +#define NET_NAME_ENUM 0 /* enumerated by kernel (default) */ +#define NET_NAME_USER 1 /* provided by user-space */ +#define NET_NAME_RENAMED 2 /* renamed by user-space */ + /* * Transmit return codes: transmit return codes originate from three different * namespaces:
@@ -1165,6 +1170,7 @@ struct net_device { * of the interface. */ char name[IFNAMSIZ]; + unsigned char name_assign_type; /* name assignment type */ /* device name hash chain, please keep it close to name[] */ struct hlist_node name_hlist;
diff --git a/net/core/dev.c b/net/core/dev.c
index b1b0c8d..3608fb2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -1083,6 +1083,7 @@ static int dev_get_valid_name(struct net *net, int dev_change_name(struct net_device *dev, const char *newname) { char oldname[IFNAMSIZ]; + unsigned char old_assign_type; int err = 0; int ret; struct net *net;
@@ -1109,10 +1110,14 @@ int dev_change_name(struct net_device *dev, const char *newname) return err; } + old_assign_type = dev->name_assign_type; + dev->name_assign_type = NET_NAME_RENAMED; + rollback: ret = device_rename(&dev->dev, dev->name); if (ret) { memcpy(dev->name, oldname, IFNAMSIZ); + dev->name_assign_type = old_assign_type; write_seqcount_end(&devnet_rename_seq); return ret; }
@@ -1141,6 +1146,8 @@ rollback: write_seqcount_begin(&devnet_rename_seq); memcpy(dev->name, oldname, IFNAMSIZ); memcpy(oldname, newname, IFNAMSIZ); + dev->name_assign_type = old_assign_type; + old_assign_type = NET_NAME_RENAMED; goto rollback; } else { pr_err("%s: name change rollback failed: %d\n",
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 9388624..72a8ce5 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c@@ -104,6 +104,7 @@ static ssize_t netdev_store(struct device *dev, struct device_attribute *attr, } NETDEVICE_SHOW_RO(dev_id, fmt_hex); +NETDEVICE_SHOW_RO(name_assign_type, fmt_dec); NETDEVICE_SHOW_RO(addr_assign_type, fmt_dec); NETDEVICE_SHOW_RO(addr_len, fmt_dec); NETDEVICE_SHOW_RO(iflink, fmt_dec);
@@ -375,6 +376,7 @@ static struct attribute *net_class_attrs[] = { &dev_attr_dev_id.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,
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 1a0dac2..e10baa0 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c@@ -1962,6 +1962,8 @@ replay: } dev->ifindex = ifm->ifi_index; + if (tb[IFLA_IFNAME]) + dev->name_assign_type = NET_NAME_USER; if (ops->newlink) { err = ops->newlink(net, dev, tb, data);
--
1.9.0