[PATCH v6 0/4] Provide netdev naming-policy via sysfs

[PATCH v6 0/4] Provide netdev naming-policy via sysfs

[David Herrmann]

Hi

This is v6 of the name_assign_type attribute for netdevs. Changes since v5 [1]:
 - Acked-by: Kay Sievers
 - rebased on net-next of today

Aimed for 3.15, but feel free to delay for 3.16 if you want it in -next for some
more time.

Thanks
David

[1] http://thread.gmane.org/gmane.linux.kernel/1673169

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(-)

-- 
1.9.1

[PATCH v6 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>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
---
 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 775cc95..e016edd 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1372,6 +1372,8 @@ 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 fdfbd1c..af50a04 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 48d81e4..b901aaa 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 4623962..a39ae01 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);
@@ -387,6 +388,7 @@ 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 d4ff417..2e4be7f 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1971,6 +1971,8 @@ 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

[PATCH v6 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>
Acked-by: Kay Sievers <kay.sievers@vrfy.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 aaa59d7..804cf0a 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 222c28b..1a938c3 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1470,6 +1470,7 @@ 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,
-- 
1.9.1

[PATCH v6 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>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
---
 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();
 
-- 
1.9.1

[PATCH v6 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Acked-by: Arend van Spriel <arend-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
Acked-by: Tom Gundersen <teg-B22kvLQNl6c@public.gmane.org>
Acked-by: Kay Sievers <kay.sievers-tD+1rO4QERM@public.gmane.org>
---
 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 f3445ac..f721ed6 100644
--- a/drivers/net/wireless/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/p2p.c
@@ -2308,6 +2308,7 @@ 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) {
-- 
1.9.1

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Re: [PATCH v6 0/4] Provide netdev naming-policy via sysfs

[David Miller]

From: David Herrmann <dh.herrmann-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Date: Wed,  2 Apr 2014 11:58:22 +0200

> This is v6 of the name_assign_type attribute for netdevs. Changes since v5 [1]:
>  - Acked-by: Kay Sievers
>  - rebased on net-next of today
> 
> Aimed for 3.15, but feel free to delay for 3.16 if you want it in -next for some
> more time.

I'm fine with the basic idea, but the implementation needs work and
this will be deferred to 3.16 in any event.

We really need to specify the name allocation type at alloc_netdev()
time, I know that's more work but that's the only way you can be sure
you caught all such cases.

I know you missed the ISDN layer, where the name can come from the
user via an ioctl().  I'm sure there were several more.

You can even do something like make alloc_netdev_enumerated()
be a shorthand for alloc_netdev(size, name, NET_NAME_ENUM, ...)

Thanks.
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