[PATCH v4 0/4] Provide netdev naming-policy via sysfs

[PATCH v4 0/4] Provide netdev naming-policy via sysfs

[David Herrmann]

Hi

This is v4 of the netdev naming-policy series. You can find v1 here:
  http://thread.gmane.org/gmane.linux.kernel/1657015
Changes since v1:
  - fix mac80211 core to set NET_NAME_ENUM for wlan%d kernel-provided names
  - acked-by udev developers
  - avoid padding after name_assign_type in "struct net_device" (David Laight)
  - move API constants to uapi header (Ben Hutchings)


This series implements a new sysfs attribute for netdevs called
"name_assign_type". It provides an integer that describes where an interface
name comes from. See Patch #1 for a description of this attribute. It is
modelled after the existing "addr_assign_type" attribute.

The main use-case is to allow udev to skip applying reliable ifnames to virtual
devices. For instance, if wifi-P2P devices are created, wpas already provides a
suitable naming-policy and udev shouldn't touch these devices. Same is true for
other virtual devices.
The idea is that if a device-name was provided by user-space, we should always
prefer fixing this naming-policy instead of making udev rename the device. For
kernel provided names that's hardly possible, though. Providing the
naming-policy source via sysfs is thus a simple way to see whether renames are
needed.

Additionally, this field allows to detect whether a netdev has been manually
renamed, which is quite useful for debugging and during crash-recovery.
Furthermore, it fixes real udev bugs if a netdev is already renamed in the
initrd and udev only runs in the real root. Detecting renames avoids overwriting
custom user provided names.

Thanks
David

David Herrmann (4):
  net: add name_assign_type netdev attribute
  mac80211: set NET_NAME_USER for user-space created ifs
  ath6kl: set NET_NAME_USER for P2P ifs
  brcmfmac: set NET_NAME_USER for P2P ifs

 drivers/net/wireless/ath/ath6kl/cfg80211.c    | 5 ++++-
 drivers/net/wireless/ath/ath6kl/cfg80211.h    | 1 +
 drivers/net/wireless/ath/ath6kl/core.c        | 4 ++--
 drivers/net/wireless/brcm80211/brcmfmac/p2p.c | 1 +
 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 ++
 net/mac80211/cfg.c                            | 2 +-
 net/mac80211/ieee80211_i.h                    | 1 +
 net/mac80211/iface.c                          | 2 ++
 net/mac80211/main.c                           | 2 +-
 13 files changed, 30 insertions(+), 5 deletions(-)

-- 
1.9.0

[PATCH v4 1/4] net: add name_assign_type netdev attribute

[David Herrmann]

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 <dh.herrmann@gmail.com>
Acked-by: Tom Gundersen <teg@jklm.no>
---
v3:
 - move api constants to uapi header (Ben Hutchings)
v4:
 - move name_assign_type so we avoid needless padding (David Laight)

 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 b8d8c80..1d48cee 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 587f9fb..4a2b360 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 fc122fd..f1bd0fe 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);
-- 
1.9.0

[PATCH v4 2/4] mac80211: set NET_NAME_USER for user-space created ifs

[David Herrmann]

The nl80211 interface allows creating new netdevs from user-space. The
name is *always* provided by user-space, so we should set NET_NAME_USER to
provide that information via sysfs. But we must not set it for the default
wlan%d names as these are kernel-provided names.

This allows udev to not rename dynamically created wifi devices (like wifi
P2P devices).

Cc: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Tom Gundersen <teg@jklm.no>
---
 net/mac80211/cfg.c         | 2 +-
 net/mac80211/ieee80211_i.h | 1 +
 net/mac80211/iface.c       | 2 ++
 net/mac80211/main.c        | 2 +-
 4 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 1acb291..34f10fe 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -31,7 +31,7 @@ static struct wireless_dev *ieee80211_add_iface(struct wiphy *wiphy,
 	struct ieee80211_sub_if_data *sdata;
 	int err;
 
-	err = ieee80211_if_add(local, name, &wdev, type, params);
+	err = ieee80211_if_add(local, name, NET_NAME_USER, &wdev, type, params);
 	if (err)
 		return ERR_PTR(err);
 
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 0d1a0f8..96f453a 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1469,6 +1469,7 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 int ieee80211_iface_init(void);
 void ieee80211_iface_exit(void);
 int ieee80211_if_add(struct ieee80211_local *local, const char *name,
+		     unsigned char name_assign_type,
 		     struct wireless_dev **new_wdev, enum nl80211_iftype type,
 		     struct vif_params *params);
 int ieee80211_if_change_type(struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index b8d331e..fe84853 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1574,6 +1574,7 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
 }
 
 int ieee80211_if_add(struct ieee80211_local *local, const char *name,
+		     unsigned char name_assign_type,
 		     struct wireless_dev **new_wdev, enum nl80211_iftype type,
 		     struct vif_params *params)
 {
@@ -1617,6 +1618,7 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 					+ IEEE80211_ENCRYPT_HEADROOM;
 		ndev->needed_tailroom = IEEE80211_ENCRYPT_TAILROOM;
 
+		ndev->name_assign_type = name_assign_type;
 		ret = dev_alloc_name(ndev, ndev->name);
 		if (ret < 0) {
 			free_netdev(ndev);
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index b055f6a5..ee32a83 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1012,7 +1012,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 
 	/* add one default STA interface if supported */
 	if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_STATION)) {
-		result = ieee80211_if_add(local, "wlan%d", NULL,
+		result = ieee80211_if_add(local, "wlan%d", NET_NAME_ENUM, NULL,
 					  NL80211_IFTYPE_STATION, NULL);
 		if (result)
 			wiphy_warn(local->hw.wiphy,
-- 
1.9.0

[PATCH v4 2/4] mac80211: set NET_NAME_USER for user-space created ifs

[David Herrmann]

The nl80211 interface allows creating new netdevs from user-space. The
name is *always* provided by user-space, so we should set NET_NAME_USER to
provide that information via sysfs. But we must not set it for the default
wlan%d names as these are kernel-provided names.

This allows udev to not rename dynamically created wifi devices (like wifi
P2P devices).

Cc: Johannes Berg <johannes.berg-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: David Herrmann <dh.herrmann-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Acked-by: Tom Gundersen <teg-B22kvLQNl6c@public.gmane.org>
---
 net/mac80211/cfg.c         | 2 +-
 net/mac80211/ieee80211_i.h | 1 +
 net/mac80211/iface.c       | 2 ++
 net/mac80211/main.c        | 2 +-
 4 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 1acb291..34f10fe 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -31,7 +31,7 @@ static struct wireless_dev *ieee80211_add_iface(struct wiphy *wiphy,
 	struct ieee80211_sub_if_data *sdata;
 	int err;
 
-	err = ieee80211_if_add(local, name, &wdev, type, params);
+	err = ieee80211_if_add(local, name, NET_NAME_USER, &wdev, type, params);
 	if (err)
 		return ERR_PTR(err);
 
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 0d1a0f8..96f453a 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1469,6 +1469,7 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 int ieee80211_iface_init(void);
 void ieee80211_iface_exit(void);
 int ieee80211_if_add(struct ieee80211_local *local, const char *name,
+		     unsigned char name_assign_type,
 		     struct wireless_dev **new_wdev, enum nl80211_iftype type,
 		     struct vif_params *params);
 int ieee80211_if_change_type(struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index b8d331e..fe84853 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1574,6 +1574,7 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
 }
 
 int ieee80211_if_add(struct ieee80211_local *local, const char *name,
+		     unsigned char name_assign_type,
 		     struct wireless_dev **new_wdev, enum nl80211_iftype type,
 		     struct vif_params *params)
 {
@@ -1617,6 +1618,7 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 					+ IEEE80211_ENCRYPT_HEADROOM;
 		ndev->needed_tailroom = IEEE80211_ENCRYPT_TAILROOM;
 
+		ndev->name_assign_type = name_assign_type;
 		ret = dev_alloc_name(ndev, ndev->name);
 		if (ret < 0) {
 			free_netdev(ndev);
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index b055f6a5..ee32a83 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1012,7 +1012,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 
 	/* add one default STA interface if supported */
 	if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_STATION)) {
-		result = ieee80211_if_add(local, "wlan%d", NULL,
+		result = ieee80211_if_add(local, "wlan%d", NET_NAME_ENUM, NULL,
 					  NL80211_IFTYPE_STATION, NULL);
 		if (result)
 			wiphy_warn(local->hw.wiphy,
-- 
1.9.0

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[PATCH v4 3/4] ath6kl: set NET_NAME_USER for P2P ifs

[David Herrmann]

P2P netdevs and other devices that are created via nl80211 from user-space
have a name provided by user-space. Therefore, set NET_NAME_USER so this
is correctly shown in sysfs.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Kalle Valo <kvalo@qca.qualcomm.com>
Acked-by: Tom Gundersen <teg@jklm.no>
---
 drivers/net/wireless/ath/ath6kl/cfg80211.c | 5 ++++-
 drivers/net/wireless/ath/ath6kl/cfg80211.h | 1 +
 drivers/net/wireless/ath/ath6kl/core.c     | 4 ++--
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath6kl/cfg80211.c b/drivers/net/wireless/ath/ath6kl/cfg80211.c
index c2c6f46..131d8ab 100644
--- a/drivers/net/wireless/ath/ath6kl/cfg80211.c
+++ b/drivers/net/wireless/ath/ath6kl/cfg80211.c
@@ -1512,7 +1512,8 @@ static struct wireless_dev *ath6kl_cfg80211_add_iface(struct wiphy *wiphy,
 		return ERR_PTR(-EINVAL);
 	}
 
-	wdev = ath6kl_interface_add(ar, name, type, if_idx, nw_type);
+	wdev = ath6kl_interface_add(ar, name, NET_NAME_USER, type,
+				    if_idx, nw_type);
 	if (!wdev)
 		return ERR_PTR(-ENOMEM);
 
@@ -3630,6 +3631,7 @@ void ath6kl_cfg80211_vif_cleanup(struct ath6kl_vif *vif)
 }
 
 struct wireless_dev *ath6kl_interface_add(struct ath6kl *ar, const char *name,
+					  unsigned char name_assign_type,
 					  enum nl80211_iftype type,
 					  u8 fw_vif_idx, u8 nw_type)
 {
@@ -3666,6 +3668,7 @@ struct wireless_dev *ath6kl_interface_add(struct ath6kl *ar, const char *name,
 			ndev->dev_addr[4] ^= 0x80;
 	}
 
+	ndev->name_assign_type = name_assign_type;
 	init_netdev(ndev);
 
 	ath6kl_init_control_info(vif);
diff --git a/drivers/net/wireless/ath/ath6kl/cfg80211.h b/drivers/net/wireless/ath/ath6kl/cfg80211.h
index b59becd..5aa57a7 100644
--- a/drivers/net/wireless/ath/ath6kl/cfg80211.h
+++ b/drivers/net/wireless/ath/ath6kl/cfg80211.h
@@ -25,6 +25,7 @@ enum ath6kl_cfg_suspend_mode {
 };
 
 struct wireless_dev *ath6kl_interface_add(struct ath6kl *ar, const char *name,
+					  unsigned char name_assign_type,
 					  enum nl80211_iftype type,
 					  u8 fw_vif_idx, u8 nw_type);
 void ath6kl_cfg80211_ch_switch_notify(struct ath6kl_vif *vif, int freq,
diff --git a/drivers/net/wireless/ath/ath6kl/core.c b/drivers/net/wireless/ath/ath6kl/core.c
index 4b46adb..3cc8145 100644
--- a/drivers/net/wireless/ath/ath6kl/core.c
+++ b/drivers/net/wireless/ath/ath6kl/core.c
@@ -195,8 +195,8 @@ int ath6kl_core_init(struct ath6kl *ar, enum ath6kl_htc_type htc_type)
 	rtnl_lock();
 
 	/* Add an initial station interface */
-	wdev = ath6kl_interface_add(ar, "wlan%d", NL80211_IFTYPE_STATION, 0,
-				    INFRA_NETWORK);
+	wdev = ath6kl_interface_add(ar, "wlan%d", NET_NAME_ENUM,
+				    NL80211_IFTYPE_STATION, 0, INFRA_NETWORK);
 
 	rtnl_unlock();
 
-- 
1.9.0

[PATCH v4 4/4] brcmfmac: set NET_NAME_USER for P2P ifs

[David Herrmann]

Netdevs created via nl80211 (currently only P2P ifs) have names provided
by user-space. Therefore, set the naming-policy to NET_NAME_USER so it is
correctly shown in sysfs.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Arend van Spriel <arend@broadcom.com>
Acked-by: Tom Gundersen <teg@jklm.no>
---
 drivers/net/wireless/brcm80211/brcmfmac/p2p.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireless/brcm80211/brcmfmac/p2p.c b/drivers/net/wireless/brcm80211/brcmfmac/p2p.c
index fc4f98b..6af4d26 100644
--- a/drivers/net/wireless/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/p2p.c
@@ -2310,6 +2310,7 @@ struct wireless_dev *brcmf_p2p_add_vif(struct wiphy *wiphy, const char *name,
 		goto fail;
 	}
 
+	ifp->ndev->name_assign_type = NET_NAME_USER;
 	strncpy(ifp->ndev->name, name, sizeof(ifp->ndev->name) - 1);
 	err = brcmf_net_attach(ifp, true);
 	if (err) {
-- 
1.9.0

Re: [PATCH v4 0/4] Provide netdev naming-policy via sysfs

[David Herrmann]

Hi Dave

Any comments on this?

Thanks
David

On Mon, Mar 17, 2014 at 8:42 PM, David Herrmann <dh.herrmann@gmail.com> wrote:
> Hi
>
> This is v4 of the netdev naming-policy series. You can find v1 here:
>   http://thread.gmane.org/gmane.linux.kernel/1657015
> Changes since v1:
>   - fix mac80211 core to set NET_NAME_ENUM for wlan%d kernel-provided names
>   - acked-by udev developers
>   - avoid padding after name_assign_type in "struct net_device" (David Laight)
>   - move API constants to uapi header (Ben Hutchings)
>
>
> This series implements a new sysfs attribute for netdevs called
> "name_assign_type". It provides an integer that describes where an interface
> name comes from. See Patch #1 for a description of this attribute. It is
> modelled after the existing "addr_assign_type" attribute.
>
> The main use-case is to allow udev to skip applying reliable ifnames to virtual
> devices. For instance, if wifi-P2P devices are created, wpas already provides a
> suitable naming-policy and udev shouldn't touch these devices. Same is true for
> other virtual devices.
> The idea is that if a device-name was provided by user-space, we should always
> prefer fixing this naming-policy instead of making udev rename the device. For
> kernel provided names that's hardly possible, though. Providing the
> naming-policy source via sysfs is thus a simple way to see whether renames are
> needed.
>
> Additionally, this field allows to detect whether a netdev has been manually
> renamed, which is quite useful for debugging and during crash-recovery.
> Furthermore, it fixes real udev bugs if a netdev is already renamed in the
> initrd and udev only runs in the real root. Detecting renames avoids overwriting
> custom user provided names.
>
> Thanks
> David
>
> David Herrmann (4):
>   net: add name_assign_type netdev attribute
>   mac80211: set NET_NAME_USER for user-space created ifs
>   ath6kl: set NET_NAME_USER for P2P ifs
>   brcmfmac: set NET_NAME_USER for P2P ifs
>
>  drivers/net/wireless/ath/ath6kl/cfg80211.c    | 5 ++++-
>  drivers/net/wireless/ath/ath6kl/cfg80211.h    | 1 +
>  drivers/net/wireless/ath/ath6kl/core.c        | 4 ++--
>  drivers/net/wireless/brcm80211/brcmfmac/p2p.c | 1 +
>  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 ++
>  net/mac80211/cfg.c                            | 2 +-
>  net/mac80211/ieee80211_i.h                    | 1 +
>  net/mac80211/iface.c                          | 2 ++
>  net/mac80211/main.c                           | 2 +-
>  13 files changed, 30 insertions(+), 5 deletions(-)
>
> --
> 1.9.0
>

Re: [PATCH v4 0/4] Provide netdev naming-policy via sysfs

[David Miller]

From: David Herrmann <dh.herrmann@gmail.com>
Date: Mon, 24 Mar 2014 09:59:18 +0100

> Any comments on this?

You had feedback that requested changes, so I'm waiting for you to post
a new series that incorporates those requested changes.

Re: [PATCH v4 0/4] Provide netdev naming-policy via sysfs

[David Herrmann]

Hi David

On Mon, Mar 24, 2014 at 5:52 PM, David Miller <davem@davemloft.net> wrote:
> From: David Herrmann <dh.herrmann@gmail.com>
> Date: Mon, 24 Mar 2014 09:59:18 +0100
>
>> Any comments on this?
>
> You had feedback that requested changes, so I'm waiting for you to post
> a new series that incorporates those requested changes.

v4 includes all suggested fixes or what are you referring to in particular?

Thanks
David

Re: [PATCH v4 0/4] Provide netdev naming-policy via sysfs

[David Miller]

From: David Herrmann <dh.herrmann@gmail.com>
Date: Mon, 24 Mar 2014 17:56:28 +0100

> v4 includes all suggested fixes or what are you referring to in particular?

If your patch series is in "Changes Requested" state in patchwork,
which this one is, you must repost it.

You can check this yourself and therefore you won't have to ask me
these kinds of things.  That's what patchwork is for, to decrease my
workload.

[PATCH v2 1/4] net: add name_assign_type netdev attribute

[David Herrmann]

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 <dh.herrmann@gmail.com>
Acked-by: Tom Gundersen <teg@jklm.no>
---
 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 b8d8c80..d3040c5 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:
@@ -1248,6 +1253,7 @@ 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 587f9fb..4a2b360 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 fc122fd..f1bd0fe 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);
-- 
1.9.0

[PATCH v4 1/4] net: add name_assign_type netdev attribute

[David Herrmann]

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 <dh.herrmann@gmail.com>
Acked-by: Tom Gundersen <teg@jklm.no>
---
v3:
 - move constants to uapi header (Ben Hutchings)
v4:
 - avoid padding after "name_assign_type" by moving it around (David Laight)

 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 b8d8c80..1d48cee 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 587f9fb..4a2b360 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 fc122fd..f1bd0fe 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);
-- 
1.9.0

Re: [PATCH v4 1/4] net: add name_assign_type netdev attribute

[David Miller]

When you post new versions of patches, you should post the entire series
again.

This way it is unambiguous what patches go which which others.

Thanks.

Re: [PATCH v4 1/4] net: add name_assign_type netdev attribute

[David Miller]

When you post new versions of patches, you should post the entire series
again.

This way it is unambiguous what patches go which which others.

Thanks.
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