mac80211: station state transition error handling

In the future, when we start notifying drivers,
state transitions could potentially fail. To make
it easier to distinguish between programming bugs
and driver failures:
 * rename sta_info_move_state() to
   sta_info_pre_move_state() which can only be
   called before the station is inserted (and
   check this with a new station flag).
 * rename sta_info_move_state_checked() to just
   plain sta_info_move_state(), as it will be
   the regular function that can fail for more
   than just one reason (bad transition or an
   error from the driver)

This makes the programming model easier -- one of
the functions can only be called before insertion
and can't fail, the other can fail.

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

1 files changed, 12 insertions, 5 deletions

diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 6f77f12dc3fc..381de37d2478 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -52,6 +52,7 @@
  * @WLAN_STA_SP: Station is in a service period, so don't try to
  *      reply to other uAPSD trigger frames or PS-Poll.
  * @WLAN_STA_4ADDR_EVENT: 4-addr event was already sent for this frame.
+ * @WLAN_STA_INSERTED: This station is inserted into the hash table.
  */
 enum ieee80211_sta_info_flags {
         WLAN_STA_AUTH,
@@ -71,6 +72,7 @@ enum ieee80211_sta_info_flags {
         WLAN_STA_UAPSD,
         WLAN_STA_SP,
         WLAN_STA_4ADDR_EVENT,
+        WLAN_STA_INSERTED,
 };
 
 enum ieee80211_sta_state {
@@ -427,13 +429,17 @@ static inline int test_and_set_sta_flag(struct sta_info *sta,
         return test_and_set_bit(flag, &sta->_flags);
 }
 
-int sta_info_move_state_checked(struct sta_info *sta,
-                                enum ieee80211_sta_state new_state);
+int sta_info_move_state(struct sta_info *sta,
+                        enum ieee80211_sta_state new_state);
 
-static inline void sta_info_move_state(struct sta_info *sta,
-                                       enum ieee80211_sta_state new_state)
+static inline void sta_info_pre_move_state(struct sta_info *sta,
+                                           enum ieee80211_sta_state new_state)
 {
-        int ret = sta_info_move_state_checked(sta, new_state);
+        int ret;
+
+        WARN_ON_ONCE(test_sta_flag(sta, WLAN_STA_INSERTED));
+
+        ret = sta_info_move_state(sta, new_state);
         WARN_ON_ONCE(ret);
 }
 
@@ -544,6 +550,7 @@ int sta_info_insert(struct sta_info *sta);
 int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU);
 int sta_info_reinsert(struct sta_info *sta);
 
+int __must_check __sta_info_destroy(struct sta_info *sta);
 int sta_info_destroy_addr(struct ieee80211_sub_if_data *sdata,
                           const u8 *addr);
 int sta_info_destroy_addr_bss(struct ieee80211_sub_if_data *sdata,