mac80211: redefine usage of the mac80211 workqueue

The mac80211 workqueue exists to enable mac80211 and drivers
to queue their own work on a single threaded workqueue. mac80211
takes care to flush the workqueue during suspend but we never
really had requirements on drivers for how they should use
the workqueue in consideration for suspend.

We extend mac80211 to document how the mac80211 workqueue should
be used, how it should not be used and finally move raw access to
the workqueue to mac80211 only. Drivers and mac80211 use helpers
to queue work onto the mac80211 workqueue:

  * ieee80211_queue_work()
  * ieee80211_queue_delayed_work()

These helpers will now warn if mac80211 already completed its
suspend cycle and someone is trying to queue work. mac80211
flushes the mac80211 workqueue prior to suspend a few times,
but we haven't taken the care to ensure drivers won't add more
work after suspend. To help with this we add a warning when
someone tries to add work and mac80211 already completed the
suspend cycle.

Drivers should ensure they cancel any work or delayed work
in the mac80211 stop() callback.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

11 files changed, 92 insertions, 49 deletions

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 6e3cca6..920ec87 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -781,7 +781,7 @@ static void ieee80211_ibss_timer(unsigned long data)
 	}
 
 	set_bit(IEEE80211_IBSS_REQ_RUN, &ifibss->request);
-	queue_work(local->hw.workqueue, &ifibss->work);
+	ieee80211_queue_work(&local->hw, &ifibss->work);
 }
 
 #ifdef CONFIG_PM
@@ -853,7 +853,7 @@ ieee80211_ibss_rx_mgmt(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 	case IEEE80211_STYPE_PROBE_REQ:
 	case IEEE80211_STYPE_AUTH:
 		skb_queue_tail(&sdata->u.ibss.skb_queue, skb);
-		queue_work(local->hw.workqueue, &sdata->u.ibss.work);
+		ieee80211_queue_work(&local->hw, &sdata->u.ibss.work);
 		return RX_QUEUED;
 	}
 
@@ -912,7 +912,7 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
 	ieee80211_recalc_idle(sdata->local);
 
 	set_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);
-	queue_work(sdata->local->hw.workqueue, &sdata->u.ibss.work);
+	ieee80211_queue_work(&sdata->local->hw, &sdata->u.ibss.work);
 
 	return 0;
 }
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index aec6853..316825b 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -614,6 +614,12 @@ struct ieee80211_local {
 
 	const struct ieee80211_ops *ops;
 
+	/*
+	 * private workqueue to mac80211. mac80211 makes this accessible
+	 * via ieee80211_queue_work()
+	 */
+	struct workqueue_struct *workqueue;
+
 	unsigned long queue_stop_reasons[IEEE80211_MAX_QUEUES];
 	/* also used to protect ampdu_ac_queue and amdpu_ac_stop_refcnt */
 	spinlock_t queue_stop_reason_lock;
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index a83087f..8c1284d 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -312,7 +312,7 @@ static int ieee80211_open(struct net_device *dev)
 	 * to fix this.
 	 */
 	if (sdata->vif.type == NL80211_IFTYPE_STATION)
-		queue_work(local->hw.workqueue, &sdata->u.mgd.work);
+		ieee80211_queue_work(&local->hw, &sdata->u.mgd.work);
 
 	netif_tx_start_all_queues(dev);
 
@@ -551,7 +551,7 @@ static int ieee80211_stop(struct net_device *dev)
 
 		ieee80211_led_radio(local, false);
 
-		flush_workqueue(local->hw.workqueue);
+		flush_workqueue(local->workqueue);
 
 		tasklet_disable(&local->tx_pending_tasklet);
 		tasklet_disable(&local->tasklet);
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 5e76dd1..22e0738 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -821,9 +821,9 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	if (hw->queues > IEEE80211_MAX_QUEUES)
 		hw->queues = IEEE80211_MAX_QUEUES;
 
-	local->hw.workqueue =
+	local->workqueue =
 		create_singlethread_workqueue(wiphy_name(local->hw.wiphy));
-	if (!local->hw.workqueue) {
+	if (!local->workqueue) {
 		result = -ENOMEM;
 		goto fail_workqueue;
 	}
@@ -913,7 +913,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	sta_info_stop(local);
  fail_sta_info:
 	debugfs_hw_del(local);
-	destroy_workqueue(local->hw.workqueue);
+	destroy_workqueue(local->workqueue);
  fail_workqueue:
 	wiphy_unregister(local->hw.wiphy);
  fail_wiphy_register:
@@ -955,7 +955,7 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
 	skb_queue_purge(&local->skb_queue);
 	skb_queue_purge(&local->skb_queue_unreliable);
 
-	destroy_workqueue(local->hw.workqueue);
+	destroy_workqueue(local->workqueue);
 	wiphy_unregister(local->hw.wiphy);
 	ieee80211_wep_free(local);
 	ieee80211_led_exit(local);
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 9a38269..2f4f518 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -54,7 +54,7 @@ static void ieee80211_mesh_housekeeping_timer(unsigned long data)
 		return;
 	}
 
-	queue_work(local->hw.workqueue, &ifmsh->work);
+	ieee80211_queue_work(local->hw.workqueue, &ifmsh->work);
 }
 
 /**
@@ -357,7 +357,7 @@ static void ieee80211_mesh_path_timer(unsigned long data)
 		return;
 	}
 
-	queue_work(local->hw.workqueue, &ifmsh->work);
+	ieee80211_queue_work(local->hw.workqueue, &ifmsh->work);
 }
 
 struct mesh_table *mesh_table_grow(struct mesh_table *tbl)
@@ -471,7 +471,7 @@ void ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
 	struct ieee80211_local *local = sdata->local;
 
 	ifmsh->housekeeping = true;
-	queue_work(local->hw.workqueue, &ifmsh->work);
+	ieee80211_queue_work(local->hw.workqueue, &ifmsh->work);
 	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON |
 						BSS_CHANGED_BEACON_ENABLED);
 }
@@ -619,7 +619,7 @@ void ieee80211_mesh_notify_scan_completed(struct ieee80211_local *local)
 	rcu_read_lock();
 	list_for_each_entry_rcu(sdata, &local->interfaces, list)
 		if (ieee80211_vif_is_mesh(&sdata->vif))
-			queue_work(local->hw.workqueue, &sdata->u.mesh.work);
+			ieee80211_queue_work(local->hw.workqueue, &sdata->u.mesh.work);
 	rcu_read_unlock();
 }
 
@@ -692,7 +692,7 @@ ieee80211_mesh_rx_mgmt(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 	case IEEE80211_STYPE_PROBE_RESP:
 	case IEEE80211_STYPE_BEACON:
 		skb_queue_tail(&ifmsh->skb_queue, skb);
-		queue_work(local->hw.workqueue, &ifmsh->work);
+		ieee80211_queue_work(local->hw.workqueue, &ifmsh->work);
 		return RX_QUEUED;
 	}
 
diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index e93c37e..11ab71a 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -660,14 +660,14 @@ static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
 	spin_unlock(&ifmsh->mesh_preq_queue_lock);
 
 	if (time_after(jiffies, ifmsh->last_preq + min_preq_int_jiff(sdata)))
-		queue_work(sdata->local->hw.workqueue, &ifmsh->work);
+		ieee80211_queue_work(sdata->local->hw.workqueue, &ifmsh->work);
 
 	else if (time_before(jiffies, ifmsh->last_preq)) {
 		/* avoid long wait if did not send preqs for a long time
 		 * and jiffies wrapped around
 		 */
 		ifmsh->last_preq = jiffies - min_preq_int_jiff(sdata) - 1;
-		queue_work(sdata->local->hw.workqueue, &ifmsh->work);
+		ieee80211_queue_work(sdata->local->hw.workqueue, &ifmsh->work);
 	} else
 		mod_timer(&ifmsh->mesh_path_timer, ifmsh->last_preq +
 						min_preq_int_jiff(sdata));
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index ee83125..0779ba1 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -565,7 +565,7 @@ static void ieee80211_chswitch_timer(unsigned long data)
 		return;
 	}
 
-	queue_work(sdata->local->hw.workqueue, &ifmgd->chswitch_work);
+	ieee80211_queue_work(&sdata->local->hw, &ifmgd->chswitch_work);
 }
 
 void ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
@@ -597,7 +597,7 @@ void ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 	sdata->local->csa_channel = new_ch;
 
 	if (sw_elem->count <= 1) {
-		queue_work(sdata->local->hw.workqueue, &ifmgd->chswitch_work);
+		ieee80211_queue_work(&sdata->local->hw, &ifmgd->chswitch_work);
 	} else {
 		ieee80211_stop_queues_by_reason(&sdata->local->hw,
 					IEEE80211_QUEUE_STOP_REASON_CSA);
@@ -763,7 +763,7 @@ void ieee80211_dynamic_ps_timer(unsigned long data)
 	if (local->quiescing || local->suspended)
 		return;
 
-	queue_work(local->hw.workqueue, &local->dynamic_ps_enable_work);
+	ieee80211_queue_work(&local->hw, &local->dynamic_ps_enable_work);
 }
 
 /* MLME */
@@ -950,7 +950,7 @@ ieee80211_direct_probe(struct ieee80211_sub_if_data *sdata,
 		 * due to work needing to be done. Hence, queue the STAs work
 		 * again for that.
 		 */
-		queue_work(local->hw.workqueue, &ifmgd->work);
+		ieee80211_queue_work(&local->hw, &ifmgd->work);
 		return RX_MGMT_CFG80211_AUTH_TO;
 	}
 
@@ -995,7 +995,7 @@ ieee80211_authenticate(struct ieee80211_sub_if_data *sdata,
 		 * due to work needing to be done. Hence, queue the STAs work
 		 * again for that.
 		 */
-		queue_work(local->hw.workqueue, &ifmgd->work);
+		ieee80211_queue_work(&local->hw, &ifmgd->work);
 		return RX_MGMT_CFG80211_AUTH_TO;
 	}
 
@@ -1124,7 +1124,7 @@ ieee80211_associate(struct ieee80211_sub_if_data *sdata,
 		 * due to work needing to be done. Hence, queue the STAs work
 		 * again for that.
 		 */
-		queue_work(local->hw.workqueue, &ifmgd->work);
+		ieee80211_queue_work(&local->hw, &ifmgd->work);
 		return RX_MGMT_CFG80211_ASSOC_TO;
 	}
 
@@ -1232,8 +1232,7 @@ void ieee80211_beacon_loss(struct ieee80211_vif *vif)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 
-	queue_work(sdata->local->hw.workqueue,
-		   &sdata->u.mgd.beacon_loss_work);
+	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.beacon_loss_work);
 }
 EXPORT_SYMBOL(ieee80211_beacon_loss);
 
@@ -1888,7 +1887,7 @@ ieee80211_rx_result ieee80211_sta_rx_mgmt(struct ieee80211_sub_if_data *sdata,
 	case IEEE80211_STYPE_DISASSOC:
 	case IEEE80211_STYPE_ACTION:
 		skb_queue_tail(&sdata->u.mgd.skb_queue, skb);
-		queue_work(local->hw.workqueue, &sdata->u.mgd.work);
+		ieee80211_queue_work(&local->hw, &sdata->u.mgd.work);
 		return RX_QUEUED;
 	}
 
@@ -2026,7 +2025,7 @@ static void ieee80211_sta_timer(unsigned long data)
 		return;
 	}
 
-	queue_work(local->hw.workqueue, &ifmgd->work);
+	ieee80211_queue_work(&local->hw, &ifmgd->work);
 }
 
 static void ieee80211_sta_work(struct work_struct *work)
@@ -2051,13 +2050,11 @@ static void ieee80211_sta_work(struct work_struct *work)
 		return;
 
 	/*
-	 * Nothing should have been stuffed into the workqueue during
-	 * the suspend->resume cycle. If this WARN is seen then there
-	 * is a bug with either the driver suspend or something in
-	 * mac80211 stuffing into the workqueue which we haven't yet
-	 * cleared during mac80211's suspend cycle.
+	 * ieee80211_queue_work() should have picked up most cases,
+	 * here we'll pick the the rest.
 	 */
-	if (WARN_ON(local->suspended))
+	if (WARN(local->suspended, "STA MLME work scheduled while "
+		 "going to suspend\n"))
 		return;
 
 	ifmgd = &sdata->u.mgd;
@@ -2113,9 +2110,9 @@ static void ieee80211_sta_work(struct work_struct *work)
 		mutex_unlock(&ifmgd->mtx);
 
 		if (test_and_clear_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request))
-			queue_delayed_work(local->hw.workqueue,
-					   &local->scan_work,
-					   round_jiffies_relative(0));
+			ieee80211_queue_delayed_work(&local->hw,
+						     &local->scan_work,
+						     round_jiffies_relative(0));
 		return;
 	}
 
@@ -2196,8 +2193,7 @@ static void ieee80211_sta_bcn_mon_timer(unsigned long data)
 	if (local->quiescing)
 		return;
 
-	queue_work(sdata->local->hw.workqueue,
-		   &sdata->u.mgd.beacon_loss_work);
+	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.beacon_loss_work);
 }
 
 static void ieee80211_sta_conn_mon_timer(unsigned long data)
@@ -2210,7 +2206,7 @@ static void ieee80211_sta_conn_mon_timer(unsigned long data)
 	if (local->quiescing)
 		return;
 
-	queue_work(local->hw.workqueue, &ifmgd->monitor_work);
+	ieee80211_queue_work(&local->hw, &ifmgd->monitor_work);
 }
 
 static void ieee80211_sta_monitor_work(struct work_struct *work)
@@ -2229,10 +2225,10 @@ static void ieee80211_restart_sta_timer(struct ieee80211_sub_if_data *sdata)
 					IEEE80211_STA_CONNECTION_POLL);
 
 		/* let's probe the connection once */
-		queue_work(sdata->local->hw.workqueue,
+		ieee80211_queue_work(&sdata->local->hw,
 			   &sdata->u.mgd.monitor_work);
 		/* and do all the other regular work too */
-		queue_work(sdata->local->hw.workqueue,
+		ieee80211_queue_work(&sdata->local->hw,
 			   &sdata->u.mgd.work);
 	}
 }
@@ -2393,7 +2389,7 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 	list_add(&wk->list, &sdata->u.mgd.work_list);
 	mutex_unlock(&ifmgd->mtx);
 
-	queue_work(sdata->local->hw.workqueue, &sdata->u.mgd.work);
+	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.work);
 	return 0;
 }
 
@@ -2467,7 +2463,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 	else
 		ifmgd->flags &= ~IEEE80211_STA_CONTROL_PORT;
 
-	queue_work(sdata->local->hw.workqueue, &sdata->u.mgd.work);
+	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.work);
 
 	err = 0;
 
diff --git a/net/mac80211/pm.c b/net/mac80211/pm.c
index 3320f7d..a5d2f1f 100644
--- a/net/mac80211/pm.c
+++ b/net/mac80211/pm.c
@@ -26,7 +26,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw)
 	/* make quiescing visible to timers everywhere */
 	mb();
 
-	flush_workqueue(local->hw.workqueue);
+	flush_workqueue(local->workqueue);
 
 	/* Don't try to run timers while suspended. */
 	del_timer_sync(&local->sta_cleanup);
@@ -117,7 +117,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw)
 	 * shouldn't be doing (or cancel everything in the
 	 * stop callback) that but better safe than sorry.
 	 */
-	flush_workqueue(local->hw.workqueue);
+	flush_workqueue(local->workqueue);
 
 	local->suspended = true;
 	/* need suspended to be visible before quiescing is false */
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 4573100..244f53f 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -385,8 +385,9 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 	spin_unlock_bh(&local->filter_lock);
 
 	/* TODO: start scan as soon as all nullfunc frames are ACKed */
-	queue_delayed_work(local->hw.workqueue, &local->scan_work,
-			   IEEE80211_CHANNEL_TIME);
+	ieee80211_queue_delayed_work(&local->hw,
+				     &local->scan_work,
+				     IEEE80211_CHANNEL_TIME);
 
 	return 0;
 }
@@ -715,8 +716,7 @@ void ieee80211_scan_work(struct work_struct *work)
 		}
 	} while (next_delay == 0);
 
-	queue_delayed_work(local->hw.workqueue, &local->scan_work,
-			   next_delay);
+	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 }
 
 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 4e1b2ba..7cffaa0 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1400,7 +1400,7 @@ static void ieee80211_xmit(struct ieee80211_sub_if_data *sdata,
 		if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 			ieee80211_stop_queues_by_reason(&local->hw,
 					IEEE80211_QUEUE_STOP_REASON_PS);
-			queue_work(local->hw.workqueue,
+			ieee80211_queue_work(&local->hw,
 					&local->dynamic_ps_disable_work);
 		}
 
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 8502936..e55d57f 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -511,6 +511,46 @@ void ieee80211_iterate_active_interfaces_atomic(
 }
 EXPORT_SYMBOL_GPL(ieee80211_iterate_active_interfaces_atomic);
 
+/*
+ * Nothing should have been stuffed into the workqueue during
+ * the suspend->resume cycle. If this WARN is seen then there
+ * is a bug with either the driver suspend or something in
+ * mac80211 stuffing into the workqueue which we haven't yet
+ * cleared during mac80211's suspend cycle.
+ */
+static bool ieee80211_can_queue_work(struct ieee80211_local *local)
+{
+        if (WARN(local->suspended, "queueing ieee80211 work while "
+		 "going to suspend\n"))
+                return false;
+
+	return true;
+}
+
+void ieee80211_queue_work(struct ieee80211_hw *hw, struct work_struct *work)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	if (!ieee80211_can_queue_work(local))
+		return;
+
+	queue_work(local->workqueue, work);
+}
+EXPORT_SYMBOL(ieee80211_queue_work);
+
+void ieee80211_queue_delayed_work(struct ieee80211_hw *hw,
+				  struct delayed_work *dwork,
+				  unsigned long delay)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	if (!ieee80211_can_queue_work(local))
+		return;
+
+	queue_delayed_work(local->workqueue, dwork, delay);
+}
+EXPORT_SYMBOL(ieee80211_queue_delayed_work);
+
 void ieee802_11_parse_elems(u8 *start, size_t len,
 			    struct ieee802_11_elems *elems)
 {
@@ -1114,3 +1154,4 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 #endif
 	return 0;
 }
+