mac80211: use chanctx reservation for AP CSA

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

It is now safe to call ieee80211_csa_finish() more
than once.

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

1 files changed, 55 insertions, 27 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 73c9e1003e25..927b4ea0128b 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2792,17 +2792,35 @@ static int __ieee80211_csa_finalize(struct ieee80211_sub_if_data *sdata)
 
         sdata_assert_lock(sdata);
         lockdep_assert_held(&local->mtx);
+        lockdep_assert_held(&local->chanctx_mtx);
 
-        sdata->radar_required = sdata->csa_radar_required;
-        err = ieee80211_vif_change_channel(sdata, &changed);
-        if (err < 0)
-                return err;
+        /*
+         * 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 (!local->use_chanctx) {
-                local->_oper_chandef = sdata->csa_chandef;
-                ieee80211_hw_config(local, 0);
+        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)
+                        return 0;
+
+                err = ieee80211_vif_use_reserved_context(sdata);
+                if (err)
+                        return err;
+
+                return 0;
         }
 
+        if (!cfg80211_chandef_identical(&sdata->vif.bss_conf.chandef,
+                                        &sdata->csa_chandef))
+                return -EINVAL;
+
         sdata->vif.csa_active = false;
 
         err = ieee80211_set_after_csa_beacon(sdata, &changed);
@@ -2839,6 +2857,7 @@ void ieee80211_csa_finalize_work(struct work_struct *work)
 
         sdata_lock(sdata);
         mutex_lock(&local->mtx);
+        mutex_lock(&local->chanctx_mtx);
 
         /* AP might have been stopped while waiting for the lock. */
         if (!sdata->vif.csa_active)
@@ -2850,6 +2869,7 @@ void ieee80211_csa_finalize_work(struct work_struct *work)
         ieee80211_csa_finalize(sdata);
 
 unlock:
+        mutex_unlock(&local->chanctx_mtx);
         mutex_unlock(&local->mtx);
         sdata_unlock(sdata);
 }
@@ -2995,7 +3015,7 @@ __ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_chanctx_conf *conf;
         struct ieee80211_chanctx *chanctx;
-        int err, num_chanctx, changed = 0;
+        int err, changed = 0;
 
         sdata_assert_lock(sdata);
         lockdep_assert_held(&local->mtx);
@@ -3010,37 +3030,43 @@ __ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
                                        &sdata->vif.bss_conf.chandef))
                 return -EINVAL;
 
+        /* don't allow another channel switch if one is already active. */
+        if (sdata->vif.csa_active)
+                return -EBUSY;
+
         mutex_lock(&local->chanctx_mtx);
         conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
                                          lockdep_is_held(&local->chanctx_mtx));
         if (!conf) {
-                mutex_unlock(&local->chanctx_mtx);
-                return -EBUSY;
+                err = -EBUSY;
+                goto out;
         }
 
-        /* don't handle for multi-VIF cases */
         chanctx = container_of(conf, struct ieee80211_chanctx, conf);
-        if (ieee80211_chanctx_refcount(local, chanctx) > 1) {
-                mutex_unlock(&local->chanctx_mtx);
-                return -EBUSY;
+        if (!chanctx) {
+                err = -EBUSY;
+                goto out;
         }
-        num_chanctx = 0;
-        list_for_each_entry_rcu(chanctx, &local->chanctx_list, list)
-                num_chanctx++;
-        mutex_unlock(&local->chanctx_mtx);
 
-        if (num_chanctx > 1)
-                return -EBUSY;
+        err = ieee80211_vif_reserve_chanctx(sdata, &params->chandef,
+                                            chanctx->mode,
+                                            params->radar_required);
+        if (err)
+                goto out;
 
-        /* don't allow another channel switch if one is already active. */
-        if (sdata->vif.csa_active)
-                return -EBUSY;
+        /* if reservation is invalid then this will fail */
+        err = ieee80211_check_combinations(sdata, NULL, chanctx->mode, 0);
+        if (err) {
+                ieee80211_vif_unreserve_chanctx(sdata);
+                goto out;
+        }
 
         err = ieee80211_set_csa_beacon(sdata, params, &changed);
-        if (err)
-                return err;
+        if (err) {
+                ieee80211_vif_unreserve_chanctx(sdata);
+                goto out;
+        }
 
-        sdata->csa_radar_required = params->radar_required;
         sdata->csa_chandef = params->chandef;
         sdata->csa_block_tx = params->block_tx;
         sdata->vif.csa_active = true;
@@ -3057,7 +3083,9 @@ __ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
                 ieee80211_csa_finalize(sdata);
         }
 
-        return 0;
+out:
+        mutex_unlock(&local->chanctx_mtx);
+        return err;
 }
 
 int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,