Return-path: Received: from mail-bk0-f51.google.com ([209.85.214.51]:59221 "EHLO mail-bk0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753739AbaCZNFn (ORCPT ); Wed, 26 Mar 2014 09:05:43 -0400 From: David Herrmann To: netdev@vger.kernel.org Cc: "David S. Miller" , Tom Gundersen , Johannes berg , linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, David Herrmann Subject: [PATCH v5 1/4] net: add name_assign_type netdev attribute Date: Wed, 26 Mar 2014 14:05:14 +0100 Message-Id: <1395839117-20090-2-git-send-email-dh.herrmann@gmail.com> (sfid-20140326_140625_673382_BCA275A6) In-Reply-To: <1395839117-20090-1-git-send-email-dh.herrmann@gmail.com> References: <1395839117-20090-1-git-send-email-dh.herrmann@gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 Acked-by: Tom Gundersen --- include/linux/netdevice.h | 2 ++ include/uapi/linux/netdevice.h | 4 ++++ net/core/dev.c | 7 +++++++ net/core/net-sysfs.c | 2 ++ net/core/rtnetlink.c | 2 ++ 5 files changed, 17 insertions(+) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 4b6d12c..48e1c15 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1376,6 +1376,8 @@ struct net_device { struct kset *queues_kset; #endif + unsigned char name_assign_type; /* name assignment 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 6b9500b..ea963e4 100644 --- a/include/uapi/linux/netdevice.h +++ b/include/uapi/linux/netdevice.h @@ -36,6 +36,10 @@ /* Initial net device group. All devices belong to group 0 by default. */ #define INIT_NETDEV_GROUP 0 +/* interface name assignment types (sysfs name_assign_type attribute) */ +#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 */ /* Media selection options. */ diff --git a/net/core/dev.c b/net/core/dev.c index 55f8e64..ee0231e 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 daed9a6..886403e 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -105,6 +105,7 @@ static ssize_t netdev_store(struct device *dev, struct device_attribute *attr, NETDEVICE_SHOW_RO(dev_id, fmt_hex); NETDEVICE_SHOW_RO(dev_port, fmt_dec); +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); @@ -377,6 +378,7 @@ 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, diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index e7c6006..4dd2a64 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1967,6 +1967,8 @@ 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); -- 1.9.1