mac80211: backport a powersave related fix
authorFelix Fietkau <nbd@openwrt.org>
Tue, 3 Jun 2014 13:59:43 +0000 (13:59 +0000)
committerFelix Fietkau <nbd@openwrt.org>
Tue, 3 Jun 2014 13:59:43 +0000 (13:59 +0000)
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
SVN-Revision: 40995

package/kernel/mac80211/patches/300-pending_work.patch

index 0a2e86b..c621ddb 100644 (file)
@@ -1,3 +1,40 @@
+commit 930b0dffd1731f3f418f9132faea720a23b7af61
+Author: Johannes Berg <johannes.berg@intel.com>
+Date:   Tue Jun 3 11:18:47 2014 +0200
+
+    mac80211: fix station/driver powersave race
+    
+    It is currently possible to have a race due to the station PS
+    unblock work like this:
+     * station goes to sleep with frames buffered in the driver
+     * driver blocks wakeup
+     * station wakes up again
+     * driver flushes/returns frames, and unblocks, which schedules
+       the unblock work
+     * unblock work starts to run, and checks that the station is
+       awake (i.e. that the WLAN_STA_PS_STA flag isn't set)
+     * we process a received frame with PM=1, setting the flag again
+     * ieee80211_sta_ps_deliver_wakeup() runs, delivering all frames
+       to the driver, and then clearing the WLAN_STA_PS_DRIVER and
+       WLAN_STA_PS_STA flags
+    
+    In this scenario, mac80211 will think that the station is awake,
+    while it really is asleep, and any TX'ed frames should be filtered
+    by the device (it will know that the station is sleeping) but then
+    passed to mac80211 again, which will not buffer it either as it
+    thinks the station is awake, and eventually the packets will be
+    dropped.
+    
+    Fix this by moving the clearing of the flags to exactly where we
+    learn about the situation. This creates a problem of reordering,
+    so introduce another flag indicating that delivery is being done,
+    this new flag also queues frames and is cleared only while the
+    spinlock is held (which the queuing code also holds) so that any
+    concurrent delivery/TX is handled correctly.
+    
+    Reported-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
+    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
+
 commit 6df35206bc6c1c6aad1d8077df5786b4a7f77873
 Author: Felix Fietkau <nbd@openwrt.org>
 Date:   Fri May 23 19:58:14 2014 +0200
@@ -101,7 +138,34 @@ Date:   Mon May 19 21:20:49 2014 +0200
                if (!budget--)
 --- a/net/mac80211/sta_info.c
 +++ b/net/mac80211/sta_info.c
-@@ -227,6 +227,7 @@ struct sta_info *sta_info_get_by_idx(str
+@@ -100,7 +100,8 @@ static void __cleanup_single_sta(struct 
+       struct ps_data *ps;
+       if (test_sta_flag(sta, WLAN_STA_PS_STA) ||
+-          test_sta_flag(sta, WLAN_STA_PS_DRIVER)) {
++          test_sta_flag(sta, WLAN_STA_PS_DRIVER) ||
++          test_sta_flag(sta, WLAN_STA_PS_DELIVER)) {
+               if (sta->sdata->vif.type == NL80211_IFTYPE_AP ||
+                   sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+                       ps = &sdata->bss->ps;
+@@ -111,6 +112,7 @@ static void __cleanup_single_sta(struct 
+               clear_sta_flag(sta, WLAN_STA_PS_STA);
+               clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
++              clear_sta_flag(sta, WLAN_STA_PS_DELIVER);
+               atomic_dec(&ps->num_sta_ps);
+               sta_info_recalc_tim(sta);
+@@ -125,7 +127,7 @@ static void __cleanup_single_sta(struct 
+       if (ieee80211_vif_is_mesh(&sdata->vif))
+               mesh_sta_cleanup(sta);
+-      cancel_work_sync(&sta->drv_unblock_wk);
++      cancel_work_sync(&sta->drv_deliver_wk);
+       /*
+        * Destroy aggregation state here. It would be nice to wait for the
+@@ -227,6 +229,7 @@ struct sta_info *sta_info_get_by_idx(str
   */
  void sta_info_free(struct ieee80211_local *local, struct sta_info *sta)
  {
@@ -109,7 +173,7 @@ Date:   Mon May 19 21:20:49 2014 +0200
        int i;
  
        if (sta->rate_ctrl)
-@@ -238,6 +239,10 @@ void sta_info_free(struct ieee80211_loca
+@@ -238,6 +241,10 @@ void sta_info_free(struct ieee80211_loca
                kfree(sta->tx_lat);
        }
  
@@ -120,6 +184,104 @@ Date:   Mon May 19 21:20:49 2014 +0200
        sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr);
  
        kfree(sta);
+@@ -252,33 +259,23 @@ static void sta_info_hash_add(struct iee
+       rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
+ }
+-static void sta_unblock(struct work_struct *wk)
++static void sta_deliver_ps_frames(struct work_struct *wk)
+ {
+       struct sta_info *sta;
+-      sta = container_of(wk, struct sta_info, drv_unblock_wk);
++      sta = container_of(wk, struct sta_info, drv_deliver_wk);
+       if (sta->dead)
+               return;
+-      if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
+-              local_bh_disable();
++      local_bh_disable();
++      if (!test_sta_flag(sta, WLAN_STA_PS_STA))
+               ieee80211_sta_ps_deliver_wakeup(sta);
+-              local_bh_enable();
+-      } else if (test_and_clear_sta_flag(sta, WLAN_STA_PSPOLL)) {
+-              clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
+-
+-              local_bh_disable();
++      else if (test_and_clear_sta_flag(sta, WLAN_STA_PSPOLL))
+               ieee80211_sta_ps_deliver_poll_response(sta);
+-              local_bh_enable();
+-      } else if (test_and_clear_sta_flag(sta, WLAN_STA_UAPSD)) {
+-              clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
+-
+-              local_bh_disable();
++      else if (test_and_clear_sta_flag(sta, WLAN_STA_UAPSD))
+               ieee80211_sta_ps_deliver_uapsd(sta);
+-              local_bh_enable();
+-      } else
+-              clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
++      local_bh_enable();
+ }
+ static int sta_prepare_rate_control(struct ieee80211_local *local,
+@@ -340,7 +337,7 @@ struct sta_info *sta_info_alloc(struct i
+       spin_lock_init(&sta->lock);
+       spin_lock_init(&sta->ps_lock);
+-      INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
++      INIT_WORK(&sta->drv_deliver_wk, sta_deliver_ps_frames);
+       INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
+       mutex_init(&sta->ampdu_mlme.mtx);
+ #ifdef CPTCFG_MAC80211_MESH
+@@ -1140,8 +1137,15 @@ void ieee80211_sta_ps_deliver_wakeup(str
+       }
+       ieee80211_add_pending_skbs(local, &pending);
+-      clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
+-      clear_sta_flag(sta, WLAN_STA_PS_STA);
++
++      /* now we're no longer in the deliver code */
++      clear_sta_flag(sta, WLAN_STA_PS_DELIVER);
++
++      /* The station might have polled and then woken up before we responded,
++       * so clear these flags now to avoid them sticking around.
++       */
++      clear_sta_flag(sta, WLAN_STA_PSPOLL);
++      clear_sta_flag(sta, WLAN_STA_UAPSD);
+       spin_unlock(&sta->ps_lock);
+       atomic_dec(&ps->num_sta_ps);
+@@ -1542,10 +1546,26 @@ void ieee80211_sta_block_awake(struct ie
+       trace_api_sta_block_awake(sta->local, pubsta, block);
+-      if (block)
++      if (block) {
+               set_sta_flag(sta, WLAN_STA_PS_DRIVER);
+-      else if (test_sta_flag(sta, WLAN_STA_PS_DRIVER))
+-              ieee80211_queue_work(hw, &sta->drv_unblock_wk);
++              return;
++      }
++
++      if (!test_sta_flag(sta, WLAN_STA_PS_DRIVER))
++              return;
++
++      if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
++              set_sta_flag(sta, WLAN_STA_PS_DELIVER);
++              clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
++              ieee80211_queue_work(hw, &sta->drv_deliver_wk);
++      } else if (test_sta_flag(sta, WLAN_STA_PSPOLL) ||
++                 test_sta_flag(sta, WLAN_STA_UAPSD)) {
++              /* must be asleep in this case */
++              clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
++              ieee80211_queue_work(hw, &sta->drv_deliver_wk);
++      } else {
++              clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
++      }
+ }
+ EXPORT_SYMBOL(ieee80211_sta_block_awake);
 --- a/net/mac80211/status.c
 +++ b/net/mac80211/status.c
 @@ -541,6 +541,23 @@ static void ieee80211_tx_latency_end_msr
@@ -161,3 +323,64 @@ Date:   Mon May 19 21:20:49 2014 +0200
                        }
                }
  
+--- a/net/mac80211/rx.c
++++ b/net/mac80211/rx.c
+@@ -1107,6 +1107,8 @@ static void sta_ps_end(struct sta_info *
+               return;
+       }
++      set_sta_flag(sta, WLAN_STA_PS_DELIVER);
++      clear_sta_flag(sta, WLAN_STA_PS_STA);
+       ieee80211_sta_ps_deliver_wakeup(sta);
+ }
+--- a/net/mac80211/sta_info.h
++++ b/net/mac80211/sta_info.h
+@@ -82,6 +82,7 @@ enum ieee80211_sta_info_flags {
+       WLAN_STA_TOFFSET_KNOWN,
+       WLAN_STA_MPSP_OWNER,
+       WLAN_STA_MPSP_RECIPIENT,
++      WLAN_STA_PS_DELIVER,
+ };
+ #define ADDBA_RESP_INTERVAL HZ
+@@ -265,7 +266,7 @@ struct ieee80211_tx_latency_stat {
+  * @last_rx_rate_vht_nss: rx status nss of last data packet
+  * @lock: used for locking all fields that require locking, see comments
+  *    in the header file.
+- * @drv_unblock_wk: used for driver PS unblocking
++ * @drv_deliver_wk: used for delivering frames after driver PS unblocking
+  * @listen_interval: listen interval of this station, when we're acting as AP
+  * @_flags: STA flags, see &enum ieee80211_sta_info_flags, do not use directly
+  * @ps_lock: used for powersave (when mac80211 is the AP) related locking
+@@ -345,7 +346,7 @@ struct sta_info {
+       void *rate_ctrl_priv;
+       spinlock_t lock;
+-      struct work_struct drv_unblock_wk;
++      struct work_struct drv_deliver_wk;
+       u16 listen_interval;
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -469,7 +469,8 @@ ieee80211_tx_h_unicast_ps_buf(struct iee
+               return TX_CONTINUE;
+       if (unlikely((test_sta_flag(sta, WLAN_STA_PS_STA) ||
+-                    test_sta_flag(sta, WLAN_STA_PS_DRIVER)) &&
++                    test_sta_flag(sta, WLAN_STA_PS_DRIVER) ||
++                    test_sta_flag(sta, WLAN_STA_PS_DELIVER)) &&
+                    !(info->flags & IEEE80211_TX_CTL_NO_PS_BUFFER))) {
+               int ac = skb_get_queue_mapping(tx->skb);
+@@ -486,7 +487,8 @@ ieee80211_tx_h_unicast_ps_buf(struct iee
+                * ahead and Tx the packet.
+                */
+               if (!test_sta_flag(sta, WLAN_STA_PS_STA) &&
+-                  !test_sta_flag(sta, WLAN_STA_PS_DRIVER)) {
++                  !test_sta_flag(sta, WLAN_STA_PS_DRIVER) &&
++                  !test_sta_flag(sta, WLAN_STA_PS_DELIVER)) {
+                       spin_unlock(&sta->ps_lock);
+                       return TX_CONTINUE;
+               }