3 files changed, 71 insertions, 54 deletions

diff --git a/include/net/fq.h b/include/net/fq.h
index 5df100b77099..2eccbbd2b559 100644
--- a/include/net/fq.h
+++ b/include/net/fq.h
@@ -19,8 +19,6 @@ struct fq_tin;
  * @flowchain: can be linked to fq_tin's new_flows or old_flows. Used for DRR++
  *	(deficit round robin) based round robin queuing similar to the one
  *	found in net/sched/sch_fq_codel.c
- * @backlogchain: can be linked to other fq_flow and fq. Used to keep track of
- *	fat flows and efficient head-dropping if packet limit is reached
  * @queue: sk_buff queue to hold packets
  * @backlog: number of bytes pending in the queue. The number of packets can be
  *	found in @queue.qlen
@@ -29,7 +27,6 @@ struct fq_tin;
 struct fq_flow {
 	struct fq_tin *tin;
 	struct list_head flowchain;
-	struct list_head backlogchain;
 	struct sk_buff_head queue;
 	u32 backlog;
 	int deficit;
@@ -47,6 +44,7 @@ struct fq_flow {
 struct fq_tin {
 	struct list_head new_flows;
 	struct list_head old_flows;
+	struct list_head tin_list;
 	struct fq_flow default_flow;
 	u32 backlog_bytes;
 	u32 backlog_packets;
@@ -60,14 +58,14 @@ struct fq_tin {
 /**
  * struct fq - main container for fair queuing purposes
  *
- * @backlogs: linked to fq_flows. Used to maintain fat flows for efficient
- *	head-dropping when @backlog reaches @limit
  * @limit: max number of packets that can be queued across all flows
  * @backlog: number of packets queued across all flows
  */
 struct fq {
 	struct fq_flow *flows;
-	struct list_head backlogs;
+	unsigned long *flows_bitmap;
+
+	struct list_head tin_backlog;
 	spinlock_t lock;
 	u32 flows_cnt;
 	u32 limit;
diff --git a/include/net/fq_impl.h b/include/net/fq_impl.h
index dd374c7f0fe5..a5f67a2c0c73 100644
--- a/include/net/fq_impl.h
+++ b/include/net/fq_impl.h
@@ -17,12 +17,24 @@ __fq_adjust_removal(struct fq *fq, struct fq_flow *flow, unsigned int packets,
 		    unsigned int bytes, unsigned int truesize)
 {
 	struct fq_tin *tin = flow->tin;
+	int idx;
 
 	tin->backlog_bytes -= bytes;
 	tin->backlog_packets -= packets;
 	flow->backlog -= bytes;
 	fq->backlog -= packets;
 	fq->memory_usage -= truesize;
+
+	if (flow->backlog)
+		return;
+
+	if (flow == &tin->default_flow) {
+		list_del_init(&tin->tin_list);
+		return;
+	}
+
+	idx = flow - fq->flows;
+	__clear_bit(idx, fq->flows_bitmap);
 }
 
 static void fq_adjust_removal(struct fq *fq,
@@ -32,24 +44,6 @@ static void fq_adjust_removal(struct fq *fq,
 	__fq_adjust_removal(fq, flow, 1, skb->len, skb->truesize);
 }
 
-static void fq_rejigger_backlog(struct fq *fq, struct fq_flow *flow)
-{
-	struct fq_flow *i;
-
-	if (flow->backlog == 0) {
-		list_del_init(&flow->backlogchain);
-	} else {
-		i = flow;
-
-		list_for_each_entry_continue(i, &fq->backlogs, backlogchain)
-			if (i->backlog < flow->backlog)
-				break;
-
-		list_move_tail(&flow->backlogchain,
-			       &i->backlogchain);
-	}
-}
-
 static struct sk_buff *fq_flow_dequeue(struct fq *fq,
 				       struct fq_flow *flow)
 {
@@ -62,7 +56,6 @@ static struct sk_buff *fq_flow_dequeue(struct fq *fq,
 		return NULL;
 
 	fq_adjust_removal(fq, flow, skb);
-	fq_rejigger_backlog(fq, flow);
 
 	return skb;
 }
@@ -90,7 +83,6 @@ static int fq_flow_drop(struct fq *fq, struct fq_flow *flow,
 	} while (packets < pending);
 
 	__fq_adjust_removal(fq, flow, packets, bytes, truesize);
-	fq_rejigger_backlog(fq, flow);
 
 	return packets;
 }
@@ -170,22 +162,36 @@ static struct fq_flow *fq_flow_classify(struct fq *fq,
 	return flow;
 }
 
-static void fq_recalc_backlog(struct fq *fq,
-			      struct fq_tin *tin,
-			      struct fq_flow *flow)
+static struct fq_flow *fq_find_fattest_flow(struct fq *fq)
 {
-	struct fq_flow *i;
+	struct fq_tin *tin;
+	struct fq_flow *flow = NULL;
+	u32 len = 0;
+	int i;
 
-	if (list_empty(&flow->backlogchain))
-		list_add_tail(&flow->backlogchain, &fq->backlogs);
+	for_each_set_bit(i, fq->flows_bitmap, fq->flows_cnt) {
+		struct fq_flow *cur = &fq->flows[i];
+		unsigned int cur_len;
 
-	i = flow;
-	list_for_each_entry_continue_reverse(i, &fq->backlogs,
-					     backlogchain)
-		if (i->backlog > flow->backlog)
-			break;
+		cur_len = cur->backlog;
+		if (cur_len <= len)
+			continue;
+
+		flow = cur;
+		len = cur_len;
+	}
+
+	list_for_each_entry(tin, &fq->tin_backlog, tin_list) {
+		unsigned int cur_len = tin->default_flow.backlog;
 
-	list_move(&flow->backlogchain, &i->backlogchain);
+		if (cur_len <= len)
+			continue;
+
+		flow = &tin->default_flow;
+		len = cur_len;
+	}
+
+	return flow;
 }
 
 static void fq_tin_enqueue(struct fq *fq,
@@ -200,6 +206,13 @@ static void fq_tin_enqueue(struct fq *fq,
 
 	flow = fq_flow_classify(fq, tin, idx, skb);
 
+	if (!flow->backlog) {
+		if (flow != &tin->default_flow)
+			__set_bit(idx, fq->flows_bitmap);
+		else if (list_empty(&tin->tin_list))
+			list_add(&tin->tin_list, &fq->tin_backlog);
+	}
+
 	flow->tin = tin;
 	flow->backlog += skb->len;
 	tin->backlog_bytes += skb->len;
@@ -207,8 +220,6 @@ static void fq_tin_enqueue(struct fq *fq,
 	fq->memory_usage += skb->truesize;
 	fq->backlog++;
 
-	fq_recalc_backlog(fq, tin, flow);
-
 	if (list_empty(&flow->flowchain)) {
 		flow->deficit = fq->quantum;
 		list_add_tail(&flow->flowchain,
@@ -218,9 +229,7 @@ static void fq_tin_enqueue(struct fq *fq,
 	__skb_queue_tail(&flow->queue, skb);
 	oom = (fq->memory_usage > fq->memory_limit);
 	while (fq->backlog > fq->limit || oom) {
-		flow = list_first_entry_or_null(&fq->backlogs,
-						struct fq_flow,
-						backlogchain);
+		flow = fq_find_fattest_flow(fq);
 		if (!flow)
 			return;
 
@@ -255,8 +264,6 @@ static void fq_flow_filter(struct fq *fq,
 		fq_adjust_removal(fq, flow, skb);
 		free_func(fq, tin, flow, skb);
 	}
-
-	fq_rejigger_backlog(fq, flow);
 }
 
 static void fq_tin_filter(struct fq *fq,
@@ -279,16 +286,18 @@ static void fq_flow_reset(struct fq *fq,
 			  struct fq_flow *flow,
 			  fq_skb_free_t free_func)
 {
+	struct fq_tin *tin = flow->tin;
 	struct sk_buff *skb;
 
 	while ((skb = fq_flow_dequeue(fq, flow)))
-		free_func(fq, flow->tin, flow, skb);
+		free_func(fq, tin, flow, skb);
 
-	if (!list_empty(&flow->flowchain))
+	if (!list_empty(&flow->flowchain)) {
 		list_del_init(&flow->flowchain);
-
-	if (!list_empty(&flow->backlogchain))
-		list_del_init(&flow->backlogchain);
+		if (list_empty(&tin->new_flows) &&
+		    list_empty(&tin->old_flows))
+			list_del_init(&tin->tin_list);
+	}
 
 	flow->tin = NULL;
 
@@ -314,6 +323,7 @@ static void fq_tin_reset(struct fq *fq,
 		fq_flow_reset(fq, flow, free_func);
 	}
 
+	WARN_ON_ONCE(!list_empty(&tin->tin_list));
 	WARN_ON_ONCE(tin->backlog_bytes);
 	WARN_ON_ONCE(tin->backlog_packets);
 }
@@ -321,7 +331,6 @@ static void fq_tin_reset(struct fq *fq,
 static void fq_flow_init(struct fq_flow *flow)
 {
 	INIT_LIST_HEAD(&flow->flowchain);
-	INIT_LIST_HEAD(&flow->backlogchain);
 	__skb_queue_head_init(&flow->queue);
 }
 
@@ -329,6 +338,7 @@ static void fq_tin_init(struct fq_tin *tin)
 {
 	INIT_LIST_HEAD(&tin->new_flows);
 	INIT_LIST_HEAD(&tin->old_flows);
+	INIT_LIST_HEAD(&tin->tin_list);
 	fq_flow_init(&tin->default_flow);
 }
 
@@ -337,8 +347,8 @@ static int fq_init(struct fq *fq, int flows_cnt)
 	int i;
 
 	memset(fq, 0, sizeof(fq[0]));
-	INIT_LIST_HEAD(&fq->backlogs);
 	spin_lock_init(&fq->lock);
+	INIT_LIST_HEAD(&fq->tin_backlog);
 	fq->flows_cnt = max_t(u32, flows_cnt, 1);
 	fq->quantum = 300;
 	fq->limit = 8192;
@@ -348,6 +358,14 @@ static int fq_init(struct fq *fq, int flows_cnt)
 	if (!fq->flows)
 		return -ENOMEM;
 
+	fq->flows_bitmap = kcalloc(BITS_TO_LONGS(fq->flows_cnt), sizeof(long),
+				   GFP_KERNEL);
+	if (!fq->flows_bitmap) {
+		kvfree(fq->flows);
+		fq->flows = NULL;
+		return -ENOMEM;
+	}
+
 	for (i = 0; i < fq->flows_cnt; i++)
 		fq_flow_init(&fq->flows[i]);
 
@@ -364,6 +382,9 @@ static void fq_reset(struct fq *fq,
 
 	kvfree(fq->flows);
 	fq->flows = NULL;
+
+	kfree(fq->flows_bitmap);
+	fq->flows_bitmap = NULL;
 }
 
 #endif
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 935a9ce65749..d981647c2863 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3337,8 +3337,6 @@ out_recalc:
 	if (head->len != orig_len) {
 		flow->backlog += head->len - orig_len;
 		tin->backlog_bytes += head->len - orig_len;
-
-		fq_recalc_backlog(fq, tin, flow);
 	}
 out:
 	spin_unlock_bh(&fq->lock);