On Mon, 2022-05-16 at 19:12 -0700, Florian Fainelli wrote:
>
> On 5/16/2022 2:56 PM, Jakub Kicinski wrote:
> > Most protocol-specific pointers in struct net_device are under
> > a respective ifdef. Wireless is the notable exception. Since
> > there's a sizable number of custom-built kernels for datacenter
> > workloads which don't build wireless it seems reasonable to
> > ifdefy those pointers as well.
> >
> > While at it move IPv4 and IPv6 pointers up, those are special
> > for obvious reasons.
> >
> > Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
>
> Could not we move to an union of pointers in the future since in many
> cases a network device can only have one of those pointers at any given
> time?
Then at the very least we'd need some kind of type that we can assign to
disambiguate, because today e.g. we have a netdev notifier (and other
code) that could get a non-wireless netdev and check like this:
static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
unsigned long state, void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct wireless_dev *wdev = dev->ieee80211_ptr;
[...]
if (!wdev)
return NOTIFY_DONE;
We could probably use the netdev->dev.type for this though, that's just
a pointer we can compare to. We'd have to set it differently (today
cfg80211 sets it based on whether or not you have ieee80211_ptr, we'd
have to turn that around), but that's not terribly hard, especially
since wireless drivers now have to call cfg80211_register_netdevice()
anyway, rather than register_netdevice() directly.
Something like the patch below might do that, but I haven't carefully
checked it yet, nor checked if there are any paths in mac80211/drivers
that might be doing this check - and it looks from Jakub's patch that
batman code would like to check this too.
johannes
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 3e5d12040726..6ea2a597f4ca 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1192,7 +1192,7 @@ void cfg80211_unregister_wdev(struct wireless_dev *wdev)
}
EXPORT_SYMBOL(cfg80211_unregister_wdev);
-static const struct device_type wiphy_type = {
+const struct device_type wiphy_type = {
.name = "wlan",
};
@@ -1369,6 +1369,9 @@ int cfg80211_register_netdevice(struct net_device *dev)
lockdep_assert_held(&rdev->wiphy.mtx);
+ /* this lets us identify our netdevs in the future */
+ SET_NETDEV_DEVTYPE(dev, &wiphy_type);
+
/* we'll take care of this */
wdev->registered = true;
wdev->registering = true;
@@ -1394,7 +1397,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
struct cfg80211_registered_device *rdev;
struct cfg80211_sched_scan_request *pos, *tmp;
- if (!wdev)
+ if (!netdev_is_wireless(dev))
return NOTIFY_DONE;
rdev = wiphy_to_rdev(wdev->wiphy);
@@ -1403,7 +1406,6 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
switch (state) {
case NETDEV_POST_INIT:
- SET_NETDEV_DEVTYPE(dev, &wiphy_type);
wdev->netdev = dev;
/* can only change netns with wiphy */
dev->features |= NETIF_F_NETNS_LOCAL;
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 2c195067ddff..e256ea5caf49 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -219,6 +219,13 @@ void cfg80211_init_wdev(struct wireless_dev *wdev);
void cfg80211_register_wdev(struct cfg80211_registered_device *rdev,
struct wireless_dev *wdev);
+extern const struct device_type wiphy_type;
+
+static inline bool netdev_is_wireless(struct net_device *dev)
+{
+ return dev && dev->dev.type == &wiphy_type && dev->ieee80211_ptr;
+}
+
static inline void wdev_lock(struct wireless_dev *wdev)
__acquires(wdev)
{
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 342dfefb6eca..58bc3750c380 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -182,7 +182,7 @@ __cfg80211_rdev_from_attrs(struct net *netns, struct nlattr **attrs)
netdev = __dev_get_by_index(netns, ifindex);
if (netdev) {
- if (netdev->ieee80211_ptr)
+ if (netdev_is_wireless(netdev))
tmp = wiphy_to_rdev(
netdev->ieee80211_ptr->wiphy);
else
@@ -2978,7 +2978,7 @@ static int nl80211_dump_wiphy_parse(struct sk_buff *skb,
ret = -ENODEV;
goto out;
}
- if (netdev->ieee80211_ptr) {
+ if (netdev_is_wireless(netdev)) {
rdev = wiphy_to_rdev(
netdev->ieee80211_ptr->wiphy);
state->filter_wiphy = rdev->wiphy_idx;
@@ -3364,7 +3364,7 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
int ifindex = nla_get_u32(info->attrs[NL80211_ATTR_IFINDEX]);
netdev = __dev_get_by_index(genl_info_net(info), ifindex);
- if (netdev && netdev->ieee80211_ptr)
+ if (netdev_is_wireless(netdev))
rdev = wiphy_to_rdev(netdev->ieee80211_ptr->wiphy);
else
netdev = NULL;
