net: add rb_to_skb() and other rb tree helpers

Geeralize private netem_rb_to_skb()

TCP rtx queue will soon be converted to rb-tree,
so we will need skb_rbtree_walk() helpers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 18a4c0e)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: edumazet

include/linux/skbuff.h

@@ -3169,6 +3169,12 @@ static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
 
 #define rb_to_skb(rb) rb_entry_safe(rb, struct sk_buff, rbnode)
 
+#define rb_to_skb(rb) rb_entry_safe(rb, struct sk_buff, rbnode)
+#define skb_rb_first(root) rb_to_skb(rb_first(root))
+#define skb_rb_last(root)  rb_to_skb(rb_last(root))
+#define skb_rb_next(skb)   rb_to_skb(rb_next(&(skb)->rbnode))
+#define skb_rb_prev(skb)   rb_to_skb(rb_prev(&(skb)->rbnode))
+
 #define skb_queue_walk(queue, skb) \
 		for (skb = (queue)->next;					\
 		     skb != (struct sk_buff *)(queue);				\
@@ -3183,6 +3189,18 @@ static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
 		for (; skb != (struct sk_buff *)(queue);			\
 		     skb = skb->next)
 
+#define skb_rbtree_walk(skb, root)						\
+		for (skb = skb_rb_first(root); skb != NULL;			\
+		     skb = skb_rb_next(skb))
+
+#define skb_rbtree_walk_from(skb)						\
+		for (; skb != NULL;						\
+		     skb = skb_rb_next(skb))
+
+#define skb_rbtree_walk_from_safe(skb, tmp)					\
+		for (; tmp = skb ? skb_rb_next(skb) : NULL, (skb != NULL);	\
+		     skb = tmp)
+
 #define skb_queue_walk_from_safe(queue, skb, tmp)				\
 		for (tmp = skb->next;						\
 		     skb != (struct sk_buff *)(queue);				\

net/ipv4/tcp_fastopen.c

@@ -458,17 +458,15 @@ bool tcp_fastopen_active_should_disable(struct sock *sk)
 void tcp_fastopen_active_disable_ofo_check(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct rb_node *p;
-	struct sk_buff *skb;
 	struct dst_entry *dst;
+	struct sk_buff *skb;
 
 	if (!tp->syn_fastopen)
 		return;
 
 	if (!tp->data_segs_in) {
-		p = rb_first(&tp->out_of_order_queue);
-		if (p && !rb_next(p)) {
-			skb = rb_entry(p, struct sk_buff, rbnode);
+		skb = skb_rb_first(&tp->out_of_order_queue);
+		if (skb && !skb_rb_next(skb)) {
 			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
 				tcp_fastopen_active_disable(sk);
 				return;

net/ipv4/tcp_input.c

@@ -4372,7 +4372,7 @@ static void tcp_ofo_queue(struct sock *sk)
 
 	p = rb_first(&tp->out_of_order_queue);
 	while (p) {
-		skb = rb_entry(p, struct sk_buff, rbnode);
+		skb = rb_to_skb(p);
 		if (after(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
 			break;
 
@@ -4440,7 +4440,7 @@ static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
 static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct rb_node **p, *q, *parent;
+	struct rb_node **p, *parent;
 	struct sk_buff *skb1;
 	u32 seq, end_seq;
 	bool fragstolen;
@@ -4503,7 +4503,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 	parent = NULL;
 	while (*p) {
 		parent = *p;
-		skb1 = rb_entry(parent, struct sk_buff, rbnode);
+		skb1 = rb_to_skb(parent);
 		if (before(seq, TCP_SKB_CB(skb1)->seq)) {
 			p = &parent->rb_left;
 			continue;
@@ -4548,9 +4548,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 
 merge_right:
 	/* Remove other segments covered by skb. */
-	while ((q = rb_next(&skb->rbnode)) != NULL) {
-		skb1 = rb_entry(q, struct sk_buff, rbnode);
-
+	while ((skb1 = skb_rb_next(skb)) != NULL) {
 		if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
 			break;
 		if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
@@ -4565,7 +4563,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 		tcp_drop(sk, skb1);
 	}
 	/* If there is no skb after us, we are the last_skb ! */
-	if (!q)
+	if (!skb1)
 		tp->ooo_last_skb = skb;
 
 add_sack:
@@ -4749,7 +4747,7 @@ static struct sk_buff *tcp_skb_next(struct sk_buff *skb, struct sk_buff_head *li
 	if (list)
 		return !skb_queue_is_last(list, skb) ? skb->next : NULL;
 
-	return rb_entry_safe(rb_next(&skb->rbnode), struct sk_buff, rbnode);
+	return skb_rb_next(skb);
 }
 
 static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb,
@@ -4778,7 +4776,7 @@ static void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb)
 
 	while (*p) {
 		parent = *p;
-		skb1 = rb_entry(parent, struct sk_buff, rbnode);
+		skb1 = rb_to_skb(parent);
 		if (before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb1)->seq))
 			p = &parent->rb_left;
 		else
@@ -4898,27 +4896,20 @@ static void tcp_collapse_ofo_queue(struct sock *sk)
 	struct tcp_sock *tp = tcp_sk(sk);
 	u32 range_truesize, sum_tiny = 0;
 	struct sk_buff *skb, *head;
-	struct rb_node *p;
 	u32 start, end;
 
-	p = rb_first(&tp->out_of_order_queue);
-	skb = rb_entry_safe(p, struct sk_buff, rbnode);
+	skb = skb_rb_first(&tp->out_of_order_queue);
 new_range:
 	if (!skb) {
-		p = rb_last(&tp->out_of_order_queue);
-		/* Note: This is possible p is NULL here. We do not
-		 * use rb_entry_safe(), as ooo_last_skb is valid only
-		 * if rbtree is not empty.
-		 */
-		tp->ooo_last_skb = rb_entry(p, struct sk_buff, rbnode);
+		tp->ooo_last_skb = skb_rb_last(&tp->out_of_order_queue);
 		return;
 	}
 	start = TCP_SKB_CB(skb)->seq;
 	end = TCP_SKB_CB(skb)->end_seq;
 	range_truesize = skb->truesize;
 
 	for (head = skb;;) {
-		skb = tcp_skb_next(skb, NULL);
+		skb = skb_rb_next(skb);
 
 		/* Range is terminated when we see a gap or when
 		 * we are at the queue end.
@@ -4974,7 +4965,7 @@ static bool tcp_prune_ofo_queue(struct sock *sk)
 		prev = rb_prev(node);
 		rb_erase(node, &tp->out_of_order_queue);
 		goal -= rb_to_skb(node)->truesize;
-		tcp_drop(sk, rb_entry(node, struct sk_buff, rbnode));
+		tcp_drop(sk, rb_to_skb(node));
 		if (!prev || goal <= 0) {
 			sk_mem_reclaim(sk);
 			if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
@@ -4984,7 +4975,7 @@ static bool tcp_prune_ofo_queue(struct sock *sk)
 		}
 		node = prev;
 	} while (node);
-	tp->ooo_last_skb = rb_entry(prev, struct sk_buff, rbnode);
+	tp->ooo_last_skb = rb_to_skb(prev);
 
 	/* Reset SACK state.  A conforming SACK implementation will
 	 * do the same at a timeout based retransmit.  When a connection

net/sched/sch_netem.c

@@ -149,12 +149,6 @@ struct netem_skb_cb {
 	ktime_t		tstamp_save;
 };
 
-
-static struct sk_buff *netem_rb_to_skb(struct rb_node *rb)
-{
-	return rb_entry(rb, struct sk_buff, rbnode);
-}
-
 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
 {
 	/* we assume we can use skb next/prev/tstamp as storage for rb_node */
@@ -365,7 +359,7 @@ static void tfifo_reset(struct Qdisc *sch)
 	struct rb_node *p;
 
 	while ((p = rb_first(&q->t_root))) {
-		struct sk_buff *skb = netem_rb_to_skb(p);
+		struct sk_buff *skb = rb_to_skb(p);
 
 		rb_erase(p, &q->t_root);
 		rtnl_kfree_skbs(skb, skb);
@@ -382,7 +376,7 @@ static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
 		struct sk_buff *skb;
 
 		parent = *p;
-		skb = netem_rb_to_skb(parent);
+		skb = rb_to_skb(parent);
 		if (tnext >= netem_skb_cb(skb)->time_to_send)
 			p = &parent->rb_right;
 		else
@@ -538,7 +532,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 				struct sk_buff *t_skb;
 				struct netem_skb_cb *t_last;
 
-				t_skb = netem_rb_to_skb(rb_last(&q->t_root));
+				t_skb = skb_rb_last(&q->t_root);
 				t_last = netem_skb_cb(t_skb);
 				if (!last ||
 				    t_last->time_to_send > last->time_to_send) {
@@ -618,7 +612,7 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 	if (p) {
 		psched_time_t time_to_send;
 
-		skb = netem_rb_to_skb(p);
+		skb = rb_to_skb(p);
 
 		/* if more time remaining? */
 		time_to_send = netem_skb_cb(skb)->time_to_send;