wifi: mac80211: implement link switching

Implement an API function and debugfs file to switch
active links.

Also provide an async version of the API so drivers
can call it in arbitrary contexts, e.g. while in the
authorized callback.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 873e81a45a97..ac2bad57933f 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -7184,4 +7184,45 @@ static inline bool ieee80211_is_tx_data(struct sk_buff *skb)
 	       ieee80211_is_data(hdr->frame_control);
 }
 
+/**
+ * ieee80211_set_active_links - set active links in client mode
+ * @vif: interface to set active links on
+ * @active_links: the new active links bitmap
+ *
+ * This changes the active links on an interface. The interface
+ * must be in client mode (in AP mode, all links are always active),
+ * and @active_links must be a subset of the vif's valid_links.
+ *
+ * If a link is switched off and another is switched on at the same
+ * time (e.g. active_links going from 0x1 to 0x10) then you will get
+ * a sequence of calls like
+ *  - change_vif_links(0x11)
+ *  - unassign_vif_chanctx(link_id=0)
+ *  - change_sta_links(0x11) for each affected STA (the AP)
+ *    (TDLS connections on now inactive links should be torn down)
+ *  - remove group keys on the old link (link_id 0)
+ *  - add new group keys (GTK/IGTK/BIGTK) on the new link (link_id 4)
+ *  - change_sta_links(0x10) for each affected STA (the AP)
+ *  - assign_vif_chanctx(link_id=4)
+ *  - change_vif_links(0x10)
+ *
+ * Note: This function acquires some mac80211 locks and must not
+ *	 be called with any driver locks held that could cause a
+ *	 lock dependency inversion. Best call it without locks.
+ */
+int ieee80211_set_active_links(struct ieee80211_vif *vif, u16 active_links);
+
+/**
+ * ieee80211_set_active_links_async - asynchronously set active links
+ * @vif: interface to set active links on
+ * @active_links: the new active links bitmap
+ *
+ * See ieee80211_set_active_links() for more information, the only
+ * difference here is that the link change is triggered async and
+ * can be called in any context, but the link switch will only be
+ * completed after it returns.
+ */
+void ieee80211_set_active_links_async(struct ieee80211_vif *vif,
+				      u16 active_links);
+
 #endif /* MAC80211_H */