[TCP]: Add tcp_for_write_queue_from_safe and use it in mtu_probe

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 9 insertions, 4 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index cdd0050b97a4..6e392babda4a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1229,6 +1229,11 @@ static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_bu
                 for (; (skb != (struct sk_buff *)&(sk)->sk_write_queue);\
                      skb = skb->next)
 
+#define tcp_for_write_queue_from_safe(skb, tmp, sk)                     \
+                for (tmp = skb->next;                                   \
+                     (skb != (struct sk_buff *)&(sk)->sk_write_queue);  \
+                     skb = tmp, tmp = skb->next)
+
 static inline struct sk_buff *tcp_send_head(struct sock *sk)
 {
         return sk->sk_send_head;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b41176f380d7..7d8583a15d02 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1350,9 +1350,7 @@ static int tcp_mtu_probe(struct sock *sk)
         tcp_insert_write_queue_before(nskb, skb, sk);
 
         len = 0;
-        while (len < probe_size) {
-                next = tcp_write_queue_next(sk, skb);
-
+        tcp_for_write_queue_from_safe(skb, next, sk) {
                 copy = min_t(int, skb->len, probe_size - len);
                 if (nskb->ip_summed)
                         skb_copy_bits(skb, 0, skb_put(nskb, copy), copy);
@@ -1381,7 +1379,9 @@ static int tcp_mtu_probe(struct sock *sk)
                 }
 
                 len += copy;
-                skb = next;
+
+                if (len >= probe_size)
+                        break;
         }
         tcp_init_tso_segs(sk, nskb, nskb->len);