mac80211: use chanctx reservation for STA CSA

Channel switch finalization is now 2-step. First
step is when driver calls chswitch_done(), the
other is when reservation is actually finalized
(which be defered for in-place reservation).

It is now safe to call ieee80211_chswitch_done()
more than once.

Also remove the ieee80211_vif_change_channel()
because it is no longer used.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 65 insertions, 34 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index eccc8492a59c..931330bbe00c 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -940,52 +940,70 @@ static void ieee80211_chswitch_work(struct work_struct *work)
                 container_of(work, struct ieee80211_sub_if_data, u.mgd.chswitch_work);
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
-        u32 changed = 0;
         int ret;
 
         if (!ieee80211_sdata_running(sdata))
                 return;
 
         sdata_lock(sdata);
+        mutex_lock(&local->mtx);
+        mutex_lock(&local->chanctx_mtx);
+
         if (!ifmgd->associated)
                 goto out;
 
-        mutex_lock(&local->mtx);
-        ret = ieee80211_vif_change_channel(sdata, &changed);
-        mutex_unlock(&local->mtx);
-        if (ret) {
+        if (!sdata->vif.csa_active)
+                goto out;
+
+        /*
+         * using reservation isn't immediate as it may be deferred until later
+         * with multi-vif. once reservation is complete it will re-schedule the
+         * work with no reserved_chanctx so verify chandef to check if it
+         * completed successfully
+         */
+
+        if (sdata->reserved_chanctx) {
+                /*
+                 * with multi-vif csa driver may call ieee80211_csa_finish()
+                 * many times while waiting for other interfaces to use their
+                 * reservations
+                 */
+                if (sdata->reserved_ready)
+                        goto out;
+
+                ret = ieee80211_vif_use_reserved_context(sdata);
+                if (ret) {
+                        sdata_info(sdata,
+                                   "failed to use reserved channel context, disconnecting (err=%d)\n",
+                                   ret);
+                        ieee80211_queue_work(&sdata->local->hw,
+                                             &ifmgd->csa_connection_drop_work);
+                        goto out;
+                }
+
+                goto out;
+        }
+
+        if (!cfg80211_chandef_identical(&sdata->vif.bss_conf.chandef,
+                                        &sdata->csa_chandef)) {
                 sdata_info(sdata,
-                           "vif channel switch failed, disconnecting\n");
+                           "failed to finalize channel switch, disconnecting\n");
                 ieee80211_queue_work(&sdata->local->hw,
                                      &ifmgd->csa_connection_drop_work);
                 goto out;
         }
 
-        if (!local->use_chanctx) {
-                local->_oper_chandef = sdata->csa_chandef;
-                /* Call "hw_config" only if doing sw channel switch.
-                 * Otherwise update the channel directly
-                 */
-                if (!local->ops->channel_switch)
-                        ieee80211_hw_config(local, 0);
-                else
-                        local->hw.conf.chandef = local->_oper_chandef;
-        }
-
         /* XXX: shouldn't really modify cfg80211-owned data! */
         ifmgd->associated->channel = sdata->csa_chandef.chan;
 
-        ieee80211_bss_info_change_notify(sdata, changed);
-
-        mutex_lock(&local->mtx);
         sdata->vif.csa_active = false;
+
         /* XXX: wait for a beacon first? */
         if (sdata->csa_block_tx) {
                 ieee80211_wake_vif_queues(local, sdata,
                                           IEEE80211_QUEUE_STOP_REASON_CSA);
                 sdata->csa_block_tx = false;
         }
-        mutex_unlock(&local->mtx);
 
         ifmgd->flags &= ~IEEE80211_STA_CSA_RECEIVED;
 
@@ -993,6 +1011,8 @@ static void ieee80211_chswitch_work(struct work_struct *work)
         ieee80211_sta_reset_conn_monitor(sdata);
 
 out:
+        mutex_unlock(&local->chanctx_mtx);
+        mutex_unlock(&local->mtx);
         sdata_unlock(sdata);
 }
 
@@ -1029,6 +1049,7 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
         struct cfg80211_bss *cbss = ifmgd->associated;
+        struct ieee80211_chanctx_conf *conf;
         struct ieee80211_chanctx *chanctx;
         enum ieee80211_band current_band;
         struct ieee80211_csa_ie csa_ie;
@@ -1072,7 +1093,22 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 
         ifmgd->flags |= IEEE80211_STA_CSA_RECEIVED;
 
+        mutex_lock(&local->mtx);
         mutex_lock(&local->chanctx_mtx);
+        conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+                                         lockdep_is_held(&local->chanctx_mtx));
+        if (!conf) {
+                sdata_info(sdata,
+                           "no channel context assigned to vif?, disconnecting\n");
+                ieee80211_queue_work(&local->hw,
+                                     &ifmgd->csa_connection_drop_work);
+                mutex_unlock(&local->chanctx_mtx);
+                mutex_unlock(&local->mtx);
+                return;
+        }
+
+        chanctx = container_of(conf, struct ieee80211_chanctx, conf);
+
         if (local->use_chanctx) {
                 u32 num_chanctx = 0;
                 list_for_each_entry(chanctx, &local->chanctx_list, list)
@@ -1085,32 +1121,27 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
                         ieee80211_queue_work(&local->hw,
                                              &ifmgd->csa_connection_drop_work);
                         mutex_unlock(&local->chanctx_mtx);
+                        mutex_unlock(&local->mtx);
                         return;
                 }
         }
 
-        if (WARN_ON(!rcu_access_pointer(sdata->vif.chanctx_conf))) {
-                ieee80211_queue_work(&local->hw,
-                                     &ifmgd->csa_connection_drop_work);
-                mutex_unlock(&local->chanctx_mtx);
-                return;
-        }
-        chanctx = container_of(rcu_access_pointer(sdata->vif.chanctx_conf),
-                               struct ieee80211_chanctx, conf);
-        if (ieee80211_chanctx_refcount(local, chanctx) > 1) {
+        res = ieee80211_vif_reserve_chanctx(sdata, &csa_ie.chandef,
+                                            chanctx->mode, false);
+        if (res) {
                 sdata_info(sdata,
-                           "channel switch with multiple interfaces on the same channel, disconnecting\n");
+                           "failed to reserve channel context for channel switch, disconnecting (err=%d)\n",
+                           res);
                 ieee80211_queue_work(&local->hw,
                                      &ifmgd->csa_connection_drop_work);
                 mutex_unlock(&local->chanctx_mtx);
+                mutex_unlock(&local->mtx);
                 return;
         }
         mutex_unlock(&local->chanctx_mtx);
 
-        sdata->csa_chandef = csa_ie.chandef;
-
-        mutex_lock(&local->mtx);
         sdata->vif.csa_active = true;
+        sdata->csa_chandef = csa_ie.chandef;
         sdata->csa_block_tx = csa_ie.mode;
 
         if (sdata->csa_block_tx)