Re: [PATCH net-next] net sysfs: remove deprecated empty wireless directory

[Heiner Kallweit <hkallweit1@gmail.com>]

On 09.11.2026 21:40, netdev-bot+sashiko@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 3 potential
> issue(s) to consider.
> 
> Critical: 0 · High: 0 · Medium: 2 · Low: 1
> 
> If you believe none of the issues are legitimate, please reply to each
> issue of Medium severity or higher and explain why the AI is wrong.
> If any of them are legitimate and you plan to respin, please let patchwork
> know by including "pw-bot: cr" as a separate line at the end of your reply
> (one such reply per series is enough).
> 
> - [Medium] The patch removes the empty /sys/class/net/<iface>/wireless
>   directory, which userspace can see.
> - [Medium] The removed wireless_group_needed() matched WEXT-only netdevs,
>   i.e. those with `ndev->wireless_handlers` set and no cfg80211…
> - [Low] The kernel-doc for struct net_device::sysfs_groups in
>   include/linux/netdevice.h still says "Space for optional device,…
> 
> --
> 
> net sysfs: remove deprecated empty wireless directory
> 
> This patch removes the empty "wireless" attribute group that
> netdev_register_kobject() created for cfg80211 and wireless extensions
> netdevs. It also shrinks net_device::sysfs_groups from 5 entries to 4.
> 
> Link: https://github.com/fedora-sysv/initscripts/commit/4e96fcecee7ab70295a5f2c52748cd57cbab60bb
> 
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index 435be7880d7e5..ac943798abca6 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -2484,7 +2484,7 @@ struct net_device {
>>  	struct dm_hw_stat_delta __rcu *dm_private;
>>  #endif
>>  	struct device		dev;
>> -	const struct attribute_group *sysfs_groups[5];
>> +	const struct attribute_group *sysfs_groups[4];
> 
> [Severity: Low]
> This isn't a bug, but should the kernel-doc for this field be updated as
> well? It still says:
> 
>  *	@sysfs_groups:	Space for optional device, statistics and wireless
>  *			sysfs groups
> 
> After this patch, netdev_register_kobject() stores only the optional
> driver group, netstat_group, netdev_phys_group and the NULL terminator.
> The comment still lists a wireless slot that nothing fills, and it does
> not mention the phys group.
> 
>>  	const struct attribute_group *sysfs_rx_queue_group;
>>  
>>  	const struct rtnl_link_ops *rtnl_link_ops;
>> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
>> index 5c0402389c6d1..cb8c82d1a4da8 100644
>> --- a/net/core/net-sysfs.c
>> +++ b/net/core/net-sysfs.c
>> @@ -910,28 +910,6 @@ static const struct attribute_group netstat_group = {
>>  	.attrs  = netstat_attrs,
>>  };
>>  
>> -static struct attribute *wireless_attrs[] = {
>> -	NULL
>> -};
>> -
>> -static const struct attribute_group wireless_group = {
>> -	.name = "wireless",
>> -	.attrs = wireless_attrs,
>> -};
> 
> [Severity: Medium]
> Could this cause a userspace regression? The group has no attributes,
> so the existence of /sys/class/net/<iface>/wireless is the whole
> interface. A script that tests for it with something like
> "[ -d /sys/class/net/$IF/wireless ]" would quietly stop finding wireless
> interfaces, without any error.
> 
> This removal has been done and reverted once before. Commit 35b2a113cb02
> removed the directory. Commit 38c1a01cf10c, which the commit message
> cites, added it back because the removal "broke (at least) Fedora's
> networking scripts", and that fix was tagged for stable 3.6.
> 
> The commit message says:
> 
>   Last known user of this deprecated feature was Fedora, until 2012.
> 
> The 2012 commit said "at least", so it did not claim Fedora was the only
> user. I can't confirm from the tree whether any current tools or local
> scripts still do this check. raspi-config's list_wlan_interfaces is one
> example worth checking.

Good catch, this script actually still checks for the wireless directory.

> 
> There also seems to be no deprecation period and no Documentation/ABI
> entry for this directory. Would it make sense for the commit message to
> mention the earlier regression and revert? It could also point users to
> the replacements: the phy80211 symlink and DEVTYPE=wlan set in
> net/wireless/core.c, or nl80211.
> 
>> -
>> -static bool wireless_group_needed(struct net_device *ndev)
>> -{
>> -#if IS_ENABLED(CONFIG_CFG80211)
>> -	if (ndev->ieee80211_ptr)
>> -		return true;
>> -#endif
>> -#if IS_ENABLED(CONFIG_WIRELESS_EXT)
>> -	if (ndev->wireless_handlers)
>> -		return true;
>> -#endif
> 
> [Severity: Medium]
> What about netdevs that use only wireless extensions? For these, the
> wireless directory appears to be the only sign in sysfs that the device
> is wireless.
> 
> One example is ps3_gelic_wireless:
> 
> drivers/net/ethernet/toshiba/ps3_gelic_wireless.c:gelic_wl_setup_netdev_ops() {
>     ...
> 	netdev->wireless_handlers = &gelic_wl_wext_handler_def;
>     ...
> }
> 
> This driver never sets ieee80211_ptr. net/wireless/core.c adds the
> phy80211 symlink and SET_NETDEV_DEVTYPE(dev, &wiphy_type) only for
> cfg80211 wdevs, so this device gets neither.
> 
> After this patch, sysfs and uevents seem to give no way to tell that
> such a device is wireless. Only /proc/net/wireless or wext ioctls like
> SIOCGIWNAME would remain.
> 
> The ipw2x00 drivers also set wireless_handlers, but they get
> ieee80211_ptr through libipw, so they keep phy80211.
> 
> Commit 38c1a01cf10c covered this case on purpose: "Also do it for both
> drivers based on the old wireless extensions and cfg80211". Should the
> commit message discuss the wext-only case, since these devices have no
> sysfs replacement?
> 
>> -	return false;
>> -}
>> -
> 
> [ ... ]
> 
--
pw-bot: cr