cfg80211: advertise possible interface combinations

Add the ability to advertise interface combinations in nl80211.
This allows the driver to indicate what the combinations are
that it supports. "Combinations" of just a single interface are
implicit, as previously. Note that cfg80211 will enforce that
the restrictions are met, but not for all drivers yet (once all
drivers are updated, we can remove the flag and enforce for all).

When no combinations are actually supported, an empty list will
be exported so that userspace can know if the kernel exported
this info or not (although it isn't clear to me what tools using
the info should do if the kernel didn't export it).

Since some interface types are purely virtual/software and don't
fit the restrictions, those are exposed in a new list of pure SW
types, not subject to restrictions. This mainly exists to handle
AP-VLAN and monitor interfaces in mac80211.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 7f89011fa22d..79a2281678bf 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -685,7 +685,7 @@ EXPORT_SYMBOL(ieee80211_alloc_hw);
 int ieee80211_register_hw(struct ieee80211_hw *hw)
 {
         struct ieee80211_local *local = hw_to_local(hw);
-        int result;
+        int result, i;
         enum ieee80211_band band;
         int channels, max_bitrates;
         bool supp_ht;
@@ -743,11 +743,19 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
                 return -ENOMEM;
 
         /* if low-level driver supports AP, we also support VLAN */
-        if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_AP))
-                local->hw.wiphy->interface_modes |= BIT(NL80211_IFTYPE_AP_VLAN);
+        if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_AP)) {
+                hw->wiphy->interface_modes |= BIT(NL80211_IFTYPE_AP_VLAN);
+                hw->wiphy->software_iftypes |= BIT(NL80211_IFTYPE_AP_VLAN);
+        }
 
         /* mac80211 always supports monitor */
-        local->hw.wiphy->interface_modes |= BIT(NL80211_IFTYPE_MONITOR);
+        hw->wiphy->interface_modes |= BIT(NL80211_IFTYPE_MONITOR);
+        hw->wiphy->software_iftypes |= BIT(NL80211_IFTYPE_MONITOR);
+
+        /* mac80211 doesn't support more than 1 channel */
+        for (i = 0; i < hw->wiphy->n_iface_combinations; i++)
+                if (hw->wiphy->iface_combinations[i].num_different_channels > 1)
+                        return -EINVAL;
 
 #ifndef CONFIG_MAC80211_MESH
         /* mesh depends on Kconfig, but drivers should set it if they want */