mac80211: allow configure_filter callback to sleep

Over time, a whole bunch of drivers have come up
with their own scheme to delay the configure_filter
operation to a workqueue. To be able to simplify
things, allow configure_filter to sleep, and add
a new prepare_multicast callback that drivers that
need the multicast address list implement. This new
callback must be atomic, but most drivers either
don't care or just calculate a hash which can be
done atomically and then uploaded to the hardware
non-atomically.

A cursory look suggests that at76c50x-usb, ar9170,
mwl8k (which is actually very broken now), rt2x00,
wl1251, wl1271 and zd1211 should make use of this
new capability.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/driver-ops.h

@@ -55,16 +55,32 @@ static inline void drv_bss_info_changed(struct ieee80211_local *local,
 	trace_drv_bss_info_changed(local, vif, info, changed);
 }
 
-static inline void drv_configure_filter(struct ieee80211_local *local,
-					unsigned int changed_flags,
-					unsigned int *total_flags,
+static inline u64 drv_prepare_multicast(struct ieee80211_local *local,
 					int mc_count,
 					struct dev_addr_list *mc_list)
 {
+	u64 ret = 0;
+
+	if (local->ops->prepare_multicast)
+		ret = local->ops->prepare_multicast(&local->hw, mc_count,
+						    mc_list);
+
+	trace_drv_prepare_multicast(local, mc_count, ret);
+
+	return ret;
+}
+
+static inline void drv_configure_filter(struct ieee80211_local *local,
+					unsigned int changed_flags,
+					unsigned int *total_flags,
+					u64 multicast)
+{
+	might_sleep();
+
 	local->ops->configure_filter(&local->hw, changed_flags, total_flags,
-				     mc_count, mc_list);
+				     multicast);
 	trace_drv_configure_filter(local, changed_flags, total_flags,
-					    mc_count);
+				   multicast);
 }
 
 static inline int drv_set_tim(struct ieee80211_local *local,

net/mac80211/driver-trace.h

@@ -191,31 +191,55 @@ TRACE_EVENT(drv_bss_info_changed,
 	)
 );
 
+TRACE_EVENT(drv_prepare_multicast,
+	TP_PROTO(struct ieee80211_local *local, int mc_count, u64 ret),
+
+	TP_ARGS(local, mc_count, ret),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		__field(int, mc_count)
+		__field(u64, ret)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		__entry->mc_count = mc_count;
+		__entry->ret = ret;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT " prepare mc (%d): %llx",
+		LOCAL_PR_ARG, __entry->mc_count,
+		(unsigned long long) __entry->ret
+	)
+);
+
 TRACE_EVENT(drv_configure_filter,
 	TP_PROTO(struct ieee80211_local *local,
 		 unsigned int changed_flags,
 		 unsigned int *total_flags,
-		 int mc_count),
+		 u64 multicast),
 
-	TP_ARGS(local, changed_flags, total_flags, mc_count),
+	TP_ARGS(local, changed_flags, total_flags, multicast),
 
 	TP_STRUCT__entry(
 		LOCAL_ENTRY
 		__field(unsigned int, changed)
 		__field(unsigned int, total)
-		__field(int, mc)
+		__field(u64, multicast)
 	),
 
 	TP_fast_assign(
 		LOCAL_ASSIGN;
 		__entry->changed = changed_flags;
 		__entry->total = *total_flags;
-		__entry->mc = mc_count;
+		__entry->multicast = multicast;
 	),
 
 	TP_printk(
-		LOCAL_PR_FMT " changed:%#x total:%#x mc:%d",
-		LOCAL_PR_ARG, __entry->changed, __entry->total, __entry->mc
+		LOCAL_PR_FMT " changed:%#x total:%#x",
+		LOCAL_PR_ARG, __entry->changed, __entry->total
 	)
 );
 

net/mac80211/ieee80211_i.h

@@ -636,6 +636,9 @@ struct ieee80211_local {
 	/* protects the aggregated multicast list and filter calls */
 	spinlock_t filter_lock;
 
+	/* used for uploading changed mc list */
+	struct work_struct reconfig_filter;
+
 	/* aggregated multicast list */
 	struct dev_addr_list *mc_list;
 	int mc_count;

net/mac80211/iface.c

@@ -227,9 +227,7 @@ static int ieee80211_open(struct net_device *dev)
 		if (sdata->u.mntr_flags & MONITOR_FLAG_OTHER_BSS)
 			local->fif_other_bss++;
 
-		spin_lock_bh(&local->filter_lock);
 		ieee80211_configure_filter(local);
-		spin_unlock_bh(&local->filter_lock);
 		break;
 	default:
 		conf.vif = &sdata->vif;
@@ -241,17 +239,13 @@ static int ieee80211_open(struct net_device *dev)
 
 		if (ieee80211_vif_is_mesh(&sdata->vif)) {
 			local->fif_other_bss++;
-			spin_lock_bh(&local->filter_lock);
 			ieee80211_configure_filter(local);
-			spin_unlock_bh(&local->filter_lock);
 
 			ieee80211_start_mesh(sdata);
 		} else if (sdata->vif.type == NL80211_IFTYPE_AP) {
 			local->fif_pspoll++;
 
-			spin_lock_bh(&local->filter_lock);
 			ieee80211_configure_filter(local);
-			spin_unlock_bh(&local->filter_lock);
 		}
 
 		changed |= ieee80211_reset_erp_info(sdata);
@@ -404,10 +398,11 @@ static int ieee80211_stop(struct net_device *dev)
 	spin_lock_bh(&local->filter_lock);
 	__dev_addr_unsync(&local->mc_list, &local->mc_count,
 			  &dev->mc_list, &dev->mc_count);
-	ieee80211_configure_filter(local);
 	spin_unlock_bh(&local->filter_lock);
 	netif_addr_unlock_bh(dev);
 
+	ieee80211_configure_filter(local);
+
 	del_timer_sync(&local->dynamic_ps_timer);
 	cancel_work_sync(&local->dynamic_ps_enable_work);
 
@@ -458,9 +453,7 @@ static int ieee80211_stop(struct net_device *dev)
 		if (sdata->u.mntr_flags & MONITOR_FLAG_OTHER_BSS)
 			local->fif_other_bss--;
 
-		spin_lock_bh(&local->filter_lock);
 		ieee80211_configure_filter(local);
-		spin_unlock_bh(&local->filter_lock);
 		break;
 	case NL80211_IFTYPE_STATION:
 		del_timer_sync(&sdata->u.mgd.chswitch_timer);
@@ -503,9 +496,7 @@ static int ieee80211_stop(struct net_device *dev)
 			local->fif_other_bss--;
 			atomic_dec(&local->iff_allmultis);
 
-			spin_lock_bh(&local->filter_lock);
 			ieee80211_configure_filter(local);
-			spin_unlock_bh(&local->filter_lock);
 
 			ieee80211_stop_mesh(sdata);
 		}
@@ -622,8 +613,8 @@ static void ieee80211_set_multicast_list(struct net_device *dev)
 	spin_lock_bh(&local->filter_lock);
 	__dev_addr_sync(&local->mc_list, &local->mc_count,
 			&dev->mc_list, &dev->mc_count);
-	ieee80211_configure_filter(local);
 	spin_unlock_bh(&local->filter_lock);
+	ieee80211_queue_work(&local->hw, &local->reconfig_filter);
 }
 
 /*

net/mac80211/main.c

@@ -50,9 +50,9 @@ struct ieee80211_tx_status_rtap_hdr {
 } __attribute__ ((packed));
 
 
-/* must be called under mdev tx lock */
 void ieee80211_configure_filter(struct ieee80211_local *local)
 {
+	u64 mc;
 	unsigned int changed_flags;
 	unsigned int new_flags = 0;
 
@@ -62,7 +62,7 @@ void ieee80211_configure_filter(struct ieee80211_local *local)
 	if (atomic_read(&local->iff_allmultis))
 		new_flags |= FIF_ALLMULTI;
 
-	if (local->monitors)
+	if (local->monitors || local->scanning)
 		new_flags |= FIF_BCN_PRBRESP_PROMISC;
 
 	if (local->fif_fcsfail)
@@ -80,20 +80,30 @@ void ieee80211_configure_filter(struct ieee80211_local *local)
 	if (local->fif_pspoll)
 		new_flags |= FIF_PSPOLL;
 
+	spin_lock_bh(&local->filter_lock);
 	changed_flags = local->filter_flags ^ new_flags;
 
+	mc = drv_prepare_multicast(local, local->mc_count, local->mc_list);
+	spin_unlock_bh(&local->filter_lock);
+
 	/* be a bit nasty */
 	new_flags |= (1<<31);
 
-	drv_configure_filter(local, changed_flags, &new_flags,
-			     local->mc_count,
-			     local->mc_list);
+	drv_configure_filter(local, changed_flags, &new_flags, mc);
 
 	WARN_ON(new_flags & (1<<31));
 
 	local->filter_flags = new_flags & ~(1<<31);
 }
 
+static void ieee80211_reconfig_filter(struct work_struct *work)
+{
+	struct ieee80211_local *local =
+		container_of(work, struct ieee80211_local, reconfig_filter);
+
+	ieee80211_configure_filter(local);
+}
+
 int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 {
 	struct ieee80211_channel *chan, *scan_chan;
@@ -692,6 +702,8 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
 
 	INIT_WORK(&local->restart_work, ieee80211_restart_work);
 
+	INIT_WORK(&local->reconfig_filter, ieee80211_reconfig_filter);
+
 	INIT_WORK(&local->dynamic_ps_enable_work,
 		  ieee80211_dynamic_ps_enable_work);
 	INIT_WORK(&local->dynamic_ps_disable_work,
@@ -946,6 +958,8 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
 
 	rtnl_unlock();
 
+	cancel_work_sync(&local->reconfig_filter);
+
 	ieee80211_clear_tx_pending(local);
 	sta_info_stop(local);
 	rate_control_deinitialize(local);

net/mac80211/scan.c

@@ -292,13 +292,7 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 	if (was_hw_scan)
 		goto done;
 
-	spin_lock_bh(&local->filter_lock);
-	local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
-	drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
-			     &local->filter_flags,
-			     local->mc_count,
-			     local->mc_list);
-	spin_unlock_bh(&local->filter_lock);
+	ieee80211_configure_filter(local);
 
 	drv_sw_scan_complete(local);
 
@@ -376,13 +370,7 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 	local->next_scan_state = SCAN_DECISION;
 	local->scan_channel_idx = 0;
 
-	spin_lock_bh(&local->filter_lock);
-	local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
-	drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
-			     &local->filter_flags,
-			     local->mc_count,
-			     local->mc_list);
-	spin_unlock_bh(&local->filter_lock);
+	ieee80211_configure_filter(local);
 
 	/* TODO: start scan as soon as all nullfunc frames are ACKed */
 	ieee80211_queue_delayed_work(&local->hw,

net/mac80211/util.c

@@ -1076,9 +1076,7 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 	/* reconfigure hardware */
 	ieee80211_hw_config(local, ~0);
 
-	spin_lock_bh(&local->filter_lock);
 	ieee80211_configure_filter(local);
-	spin_unlock_bh(&local->filter_lock);
 
 	/* Finally also reconfigure all the BSS information */
 	list_for_each_entry(sdata, &local->interfaces, list) {