mac80211: Stop forwarding mesh traffic when tx queues are full

Tx flow control for non-mesh modes of operation only needs to act on the
net device queues: when the hardware queues are full we stop accepting
traffic from the net device.  In mesh, however, we also need to stop
forwarding traffic.  This patch checks the hardware queues before
attempting to forward a mesh frame.
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/debugfs_netdev.c

@@ -340,6 +340,8 @@ IEEE80211_IF_FILE(fwded_mcast, u.mesh.mshstats.fwded_mcast, DEC);
 IEEE80211_IF_FILE(fwded_unicast, u.mesh.mshstats.fwded_unicast, DEC);
 IEEE80211_IF_FILE(fwded_frames, u.mesh.mshstats.fwded_frames, DEC);
 IEEE80211_IF_FILE(dropped_frames_ttl, u.mesh.mshstats.dropped_frames_ttl, DEC);
+IEEE80211_IF_FILE(dropped_frames_congestion,
+		u.mesh.mshstats.dropped_frames_congestion, DEC);
 IEEE80211_IF_FILE(dropped_frames_no_route,
 		u.mesh.mshstats.dropped_frames_no_route, DEC);
 IEEE80211_IF_FILE(estab_plinks, u.mesh.mshstats.estab_plinks, ATOMIC);
@@ -463,6 +465,7 @@ static void add_mesh_stats(struct ieee80211_sub_if_data *sdata)
 	MESHSTATS_ADD(fwded_frames);
 	MESHSTATS_ADD(dropped_frames_ttl);
 	MESHSTATS_ADD(dropped_frames_no_route);
+	MESHSTATS_ADD(dropped_frames_congestion);
 	MESHSTATS_ADD(estab_plinks);
 #undef MESHSTATS_ADD
 }

net/mac80211/ieee80211_i.h

@@ -261,6 +261,7 @@ struct mesh_stats {
 	__u32 fwded_frames;		/* Mesh total forwarded frames */
 	__u32 dropped_frames_ttl;	/* Not transmitted since mesh_ttl == 0*/
 	__u32 dropped_frames_no_route;	/* Not transmitted, no route found */
+	__u32 dropped_frames_congestion;/* Not forwarded due to congestion */
 	atomic_t estab_plinks;
 };
 

net/mac80211/rx.c

@@ -1844,6 +1844,12 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 		/* illegal frame */
 		return RX_DROP_MONITOR;
 
+	if (ieee80211_queue_stopped(&local->hw, skb_get_queue_mapping(skb))) {
+		IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.mesh,
+						dropped_frames_congestion);
+		return RX_DROP_MONITOR;
+	}
+
 	if (mesh_hdr->flags & MESH_FLAGS_AE) {
 		struct mesh_path *mppath;
 		char *proxied_addr;