[DCCP]: Introduce dccp_wait_for_ccid and use it in dccp_write_xmit

This is not quite what I think we should have long term but improves
performance for now, so lets use it till we get CCID3 working well,
then we can think about using sk_write_queue, perhaps using some ideas
from Juwen Lai's old stack for 2.4.20.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 62 insertions, 6 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index cf93b019ecbe..9866dc175258 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -985,7 +985,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk,
                 ccid3_pr_debug("send_packet delay=%ld\n", delay);
                 delay /= -1000;
                 /* divide by -1000 is to convert to ms and get sign right */
-                rc = delay > 0 ? -EAGAIN : 0;
+                rc = delay > 0 ? delay : 0;
                 break;
         default:
                 printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index c6ba07ea1a9f..6ba21509e797 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -126,8 +126,7 @@ extern void dccp_send_delayed_ack(struct sock *sk);
 extern void dccp_send_sync(struct sock *sk, const u64 seq,
                            const enum dccp_pkt_type pkt_type);
 
-extern int dccp_write_xmit(struct sock *sk, struct sk_buff *skb,
-                           const int len);
+extern int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo);
 
 extern void dccp_init_xmit_timers(struct sock *sk);
 static inline void dccp_clear_xmit_timers(struct sock *sk)
diff --git a/net/dccp/output.c b/net/dccp/output.c
index f96dedd3ad5e..116f6db5678d 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -150,14 +150,71 @@ unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
         return mss_now;
 }
 
-int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, const int len)
+/**
+ * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
+ * @sk: socket to wait for
+ * @timeo: for how long
+ */
+static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
+                              long *timeo)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        DEFINE_WAIT(wait);
+        long delay;
+        int rc;
+
+        while (1) {
+                prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
+
+                if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+                        goto do_error;
+                if (!*timeo)
+                        goto do_nonblock;
+                if (signal_pending(current))
+                        goto do_interrupted;
+
+                rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
+                                            skb->len);
+                if (rc <= 0)
+                        break;
+                delay = msecs_to_jiffies(rc);
+                if (delay > *timeo || delay < 0)
+                        goto do_nonblock;
+
+                sk->sk_write_pending++;
+                release_sock(sk);
+                *timeo -= schedule_timeout(delay);
+                lock_sock(sk);
+                sk->sk_write_pending--;
+        }
+out:
+        finish_wait(sk->sk_sleep, &wait);
+        return rc;
+
+do_error:
+        rc = -EPIPE;
+        goto out;
+do_nonblock:
+        rc = -EAGAIN;
+        goto out;
+do_interrupted:
+        rc = sock_intr_errno(*timeo);
+        goto out;
+}
+
+int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
 {
         const struct dccp_sock *dp = dccp_sk(sk);
-        int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, len);
+        int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
+                                         skb->len);
+
+        if (err > 0)
+                err = dccp_wait_for_ccid(sk, skb, timeo);
 
         if (err == 0) {
                 const struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+                const int len = skb->len;
 
                 if (sk->sk_state == DCCP_PARTOPEN) {
                         /* See 8.1.5.  Handshake Completion */
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index f97e92ea34f3..f4da6561e40c 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -261,7 +261,7 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         if (rc != 0)
                 goto out_discard;
 
-        rc = dccp_write_xmit(sk, skb, len);
+        rc = dccp_write_xmit(sk, skb, &timeo);
         /*
          * XXX we don't use sk_write_queue, so just discard the packet.
          *     Current plan however is to _use_ sk_write_queue with