mac80211: add sta_state callback

(based on Eliad's patch)

Add a callback to notify the low-level driver whenever
the state of a station changes. The driver is only
notified when the station is actually in the mac80211
hash table, not for pre-insert state transitions.

To allow the driver to replace sta_add/remove calls
with this, call extra transitions with the NOTEXIST
state.

This callback can fail, so we need to be careful in
handling it when a station is inserted, particularly
in the IBSS case where we still keep the station entry
around for mac80211 purposes.

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

7 files changed, 164 insertions, 28 deletions

diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index b8673f6100df..4bd266ec5333 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -478,6 +478,28 @@ static inline void drv_sta_remove(struct ieee80211_local *local,
         trace_drv_return_void(local);
 }
 
+static inline __must_check
+int drv_sta_state(struct ieee80211_local *local,
+                  struct ieee80211_sub_if_data *sdata,
+                  struct sta_info *sta,
+                  enum ieee80211_sta_state old_state,
+                  enum ieee80211_sta_state new_state)
+{
+        int ret = 0;
+
+        might_sleep();
+
+        sdata = get_bss_sdata(sdata);
+        check_sdata_in_driver(sdata);
+
+        trace_drv_sta_state(local, sdata, &sta->sta, old_state, new_state);
+        if (local->ops->sta_state)
+                ret = local->ops->sta_state(&local->hw, &sdata->vif, &sta->sta,
+                                            old_state, new_state);
+        trace_drv_return_int(local, ret);
+        return ret;
+}
+
 static inline int drv_conf_tx(struct ieee80211_local *local,
                               struct ieee80211_sub_if_data *sdata, u16 queue,
                               const struct ieee80211_tx_queue_params *params)
diff --git a/net/mac80211/driver-trace.h b/net/mac80211/driver-trace.h
index 6e9df8fd8fb8..384e2f08c187 100644
--- a/net/mac80211/driver-trace.h
+++ b/net/mac80211/driver-trace.h
@@ -635,6 +635,38 @@ TRACE_EVENT(drv_sta_notify,
         )
 );
 
+TRACE_EVENT(drv_sta_state,
+        TP_PROTO(struct ieee80211_local *local,
+                 struct ieee80211_sub_if_data *sdata,
+                 struct ieee80211_sta *sta,
+                 enum ieee80211_sta_state old_state,
+                 enum ieee80211_sta_state new_state),
+
+        TP_ARGS(local, sdata, sta, old_state, new_state),
+
+        TP_STRUCT__entry(
+                LOCAL_ENTRY
+                VIF_ENTRY
+                STA_ENTRY
+                __field(u32, old_state)
+                __field(u32, new_state)
+        ),
+
+        TP_fast_assign(
+                LOCAL_ASSIGN;
+                VIF_ASSIGN;
+                STA_ASSIGN;
+                __entry->old_state = old_state;
+                __entry->new_state = new_state;
+        ),
+
+        TP_printk(
+                LOCAL_PR_FMT  VIF_PR_FMT  STA_PR_FMT " state: %d->%d",
+                LOCAL_PR_ARG, VIF_PR_ARG, STA_PR_ARG,
+                __entry->old_state, __entry->new_state
+        )
+);
+
 TRACE_EVENT(drv_sta_add,
         TP_PROTO(struct ieee80211_local *local,
                  struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 6192caadfab9..f4fc540aac17 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -535,6 +535,9 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
         int priv_size, i;
         struct wiphy *wiphy;
 
+        if (WARN_ON(ops->sta_state && (ops->sta_add || ops->sta_remove)))
+                return NULL;
+
         /* Ensure 32-byte alignment of our private data and hw private data.
          * We use the wiphy priv data for both our ieee80211_local and for
          * the driver's private data
diff --git a/net/mac80211/pm.c b/net/mac80211/pm.c
index c65ff471acce..af49ac4f0826 100644
--- a/net/mac80211/pm.c
+++ b/net/mac80211/pm.c
@@ -97,9 +97,17 @@ int __ieee80211_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
         /* tear down aggregation sessions and remove STAs */
         mutex_lock(&local->sta_mtx);
         list_for_each_entry(sta, &local->sta_list, list) {
-                if (sta->uploaded)
+                if (sta->uploaded) {
+                        enum ieee80211_sta_state state;
+
                         drv_sta_remove(local, sta->sdata, &sta->sta);
 
+                        state = sta->sta_state;
+                        for (; state > IEEE80211_STA_NOTEXIST; state--)
+                                WARN_ON(drv_sta_state(local, sdata, sta,
+                                                      state, state - 1));
+                }
+
                 mesh_plink_quiesce(sta);
         }
         mutex_unlock(&local->sta_mtx);
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 464bc691644b..fcd9027c6699 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -351,6 +351,38 @@ static int sta_info_insert_check(struct sta_info *sta)
         return 0;
 }
 
+static int sta_info_insert_drv_state(struct ieee80211_local *local,
+                                     struct ieee80211_sub_if_data *sdata,
+                                     struct sta_info *sta)
+{
+        enum ieee80211_sta_state state;
+        int err = 0;
+
+        for (state = IEEE80211_STA_NOTEXIST; state < sta->sta_state; state++) {
+                err = drv_sta_state(local, sdata, sta, state, state + 1);
+                if (err)
+                        break;
+        }
+
+        if (!err) {
+                sta->uploaded = true;
+                return 0;
+        }
+
+        if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
+                printk(KERN_DEBUG
+                       "%s: failed to move IBSS STA %pM to state %d (%d) - keeping it anyway.\n",
+                       sdata->name, sta->sta.addr, state + 1, err);
+                err = 0;
+        }
+
+        /* unwind on error */
+        for (; state > IEEE80211_STA_NOTEXIST; state--)
+                WARN_ON(drv_sta_state(local, sdata, sta, state, state - 1));
+
+        return err;
+}
+
 /*
  * should be called with sta_mtx locked
  * this function replaces the mutex lock
@@ -392,8 +424,11 @@ static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU)
                         printk(KERN_DEBUG "%s: failed to add IBSS STA %pM to "
                                           "driver (%d) - keeping it anyway.\n",
                                sdata->name, sta->sta.addr, err);
-                } else
-                        sta->uploaded = true;
+                } else {
+                        err = sta_info_insert_drv_state(local, sdata, sta);
+                        if (err)
+                                goto out_err;
+                }
         }
 
         if (!dummy_reinsert) {
@@ -759,15 +794,19 @@ int __must_check __sta_info_destroy(struct sta_info *sta)
                 RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);
 
         while (sta->sta_state > IEEE80211_STA_NONE) {
-                int err = sta_info_move_state(sta, sta->sta_state - 1);
-                if (err) {
+                ret = sta_info_move_state(sta, sta->sta_state - 1);
+                if (ret) {
                         WARN_ON_ONCE(1);
                         break;
                 }
         }
 
-        if (sta->uploaded)
+        if (sta->uploaded) {
                 drv_sta_remove(local, sdata, &sta->sta);
+                ret = drv_sta_state(local, sdata, sta, IEEE80211_STA_NONE,
+                                    IEEE80211_STA_NOTEXIST);
+                WARN_ON_ONCE(ret != 0);
+        }
 
         /*
          * At this point, after we wait for an RCU grace period,
@@ -1404,20 +1443,58 @@ int sta_info_move_state(struct sta_info *sta,
         if (sta->sta_state == new_state)
                 return 0;
 
+        /* check allowed transitions first */
+
+        switch (new_state) {
+        case IEEE80211_STA_NONE:
+                if (sta->sta_state != IEEE80211_STA_AUTH)
+                        return -EINVAL;
+                break;
+        case IEEE80211_STA_AUTH:
+                if (sta->sta_state != IEEE80211_STA_NONE &&
+                    sta->sta_state != IEEE80211_STA_ASSOC)
+                        return -EINVAL;
+                break;
+        case IEEE80211_STA_ASSOC:
+                if (sta->sta_state != IEEE80211_STA_AUTH &&
+                    sta->sta_state != IEEE80211_STA_AUTHORIZED)
+                        return -EINVAL;
+                break;
+        case IEEE80211_STA_AUTHORIZED:
+                if (sta->sta_state != IEEE80211_STA_ASSOC)
+                        return -EINVAL;
+                break;
+        default:
+                WARN(1, "invalid state %d", new_state);
+                return -EINVAL;
+        }
+
+        printk(KERN_DEBUG "%s: moving STA %pM to state %d\n",
+                sta->sdata->name, sta->sta.addr, new_state);
+
+        /*
+         * notify the driver before the actual changes so it can
+         * fail the transition
+         */
+        if (test_sta_flag(sta, WLAN_STA_INSERTED)) {
+                int err = drv_sta_state(sta->local, sta->sdata, sta,
+                                        sta->sta_state, new_state);
+                if (err)
+                        return err;
+        }
+
+        /* reflect the change in all state variables */
+
         switch (new_state) {
         case IEEE80211_STA_NONE:
                 if (sta->sta_state == IEEE80211_STA_AUTH)
                         clear_bit(WLAN_STA_AUTH, &sta->_flags);
-                else
-                        return -EINVAL;
                 break;
         case IEEE80211_STA_AUTH:
                 if (sta->sta_state == IEEE80211_STA_NONE)
                         set_bit(WLAN_STA_AUTH, &sta->_flags);
                 else if (sta->sta_state == IEEE80211_STA_ASSOC)
                         clear_bit(WLAN_STA_ASSOC, &sta->_flags);
-                else
-                        return -EINVAL;
                 break;
         case IEEE80211_STA_ASSOC:
                 if (sta->sta_state == IEEE80211_STA_AUTH) {
@@ -1426,24 +1503,19 @@ int sta_info_move_state(struct sta_info *sta,
                         if (sta->sdata->vif.type == NL80211_IFTYPE_AP)
                                 atomic_dec(&sta->sdata->u.ap.num_sta_authorized);
                         clear_bit(WLAN_STA_AUTHORIZED, &sta->_flags);
-                } else
-                        return -EINVAL;
+                }
                 break;
         case IEEE80211_STA_AUTHORIZED:
                 if (sta->sta_state == IEEE80211_STA_ASSOC) {
                         if (sta->sdata->vif.type == NL80211_IFTYPE_AP)
                                 atomic_inc(&sta->sdata->u.ap.num_sta_authorized);
                         set_bit(WLAN_STA_AUTHORIZED, &sta->_flags);
-                } else
-                        return -EINVAL;
+                }
                 break;
         default:
-                WARN(1, "invalid state %d", new_state);
-                return -EINVAL;
+                break;
         }
 
-        printk(KERN_DEBUG "%s: moving STA %pM to state %d\n",
-                sta->sdata->name, sta->sta.addr, new_state);
         sta->sta_state = new_state;
 
         return 0;
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index da4b03c1c3bc..2ee808860007 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -75,15 +75,6 @@ enum ieee80211_sta_info_flags {
         WLAN_STA_INSERTED,
 };
 
-enum ieee80211_sta_state {
-        /* NOTE: These need to be ordered correctly! */
-        IEEE80211_STA_NOTEXIST,
-        IEEE80211_STA_NONE,
-        IEEE80211_STA_AUTH,
-        IEEE80211_STA_ASSOC,
-        IEEE80211_STA_AUTHORIZED,
-};
-
 #define STA_TID_NUM 16
 #define ADDBA_RESP_INTERVAL HZ
 #define HT_AGG_MAX_RETRIES              15
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index d4966e88aa49..8f8b4ecc776f 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1184,8 +1184,16 @@ int ieee80211_reconfig(struct ieee80211_local *local)
         /* add STAs back */
         mutex_lock(&local->sta_mtx);
         list_for_each_entry(sta, &local->sta_list, list) {
-                if (sta->uploaded)
+                if (sta->uploaded) {
+                        enum ieee80211_sta_state state;
+
                         WARN_ON(drv_sta_add(local, sta->sdata, &sta->sta));
+
+                        for (state = IEEE80211_STA_NOTEXIST;
+                             state < sta->sta_state - 1; state++)
+                                WARN_ON(drv_sta_state(local, sta->sdata, sta,
+                                                      state, state + 1));
+                }
         }
         mutex_unlock(&local->sta_mtx);