[DCCP]: Introduce tx buffering

This adds transmit buffering to DCCP.

I have tested with CCID2/3 and with loss and rate limiting.

Signed off by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 73 insertions, 37 deletions

diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 676333b9fad0..2d7671c92c0b 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -438,6 +438,7 @@ struct dccp_ackvec;
  * @dccps_role - Role of this sock, one of %dccp_role
  * @dccps_ndp_count - number of Non Data Packets since last data packet
  * @dccps_hc_rx_ackvec - rx half connection ack vector
+ * @dccps_xmit_timer - timer for when CCID is not ready to send
  */
 struct dccp_sock {
         /* inet_connection_sock has to be the first member of dccp_sock */
@@ -470,6 +471,7 @@ struct dccp_sock {
         enum dccp_role                  dccps_role:2;
         __u8                            dccps_hc_rx_insert_options:1;
         __u8                            dccps_hc_tx_insert_options:1;
+        struct timer_list               dccps_xmit_timer;
 };
  
 static inline struct dccp_sock *dccp_sk(const struct sock *sk)
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index a5c5475724c0..0a21be437ed3 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -130,7 +130,7 @@ 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, long *timeo);
+extern void dccp_write_xmit(struct sock *sk, int block);
 extern void dccp_write_space(struct sock *sk);
 
 extern void dccp_init_xmit_timers(struct sock *sk);
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 58669beee132..7102e3aed4ca 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -198,7 +198,7 @@ static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
         while (1) {
                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 
-                if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+                if (sk->sk_err)
                         goto do_error;
                 if (!*timeo)
                         goto do_nonblock;
@@ -234,37 +234,72 @@ do_interrupted:
         goto out;
 }
 
-int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
+static void dccp_write_xmit_timer(unsigned long data) {
+        struct sock *sk = (struct sock *)data;
+        struct dccp_sock *dp = dccp_sk(sk);
+
+        bh_lock_sock(sk);
+        if (sock_owned_by_user(sk))
+                sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1);
+        else
+                dccp_write_xmit(sk, 0);
+        bh_unlock_sock(sk);
+        sock_put(sk);
+}
+
+void dccp_write_xmit(struct sock *sk, int block)
 {
-        const struct dccp_sock *dp = dccp_sk(sk);
-        int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
+        struct dccp_sock *dp = dccp_sk(sk);
+        struct sk_buff *skb;
+        long timeo = 30000;     /* If a packet is taking longer than 2 secs
+                                   we have other issues */
+
+        while ((skb = skb_peek(&sk->sk_write_queue))) {
+                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) {
+                        if (!block) {
+                                sk_reset_timer(sk, &dp->dccps_xmit_timer,
+                                                msecs_to_jiffies(err)+jiffies);
+                                break;
+                        } else
+                                err = dccp_wait_for_ccid(sk, skb, &timeo);
+                        if (err) {
+                                printk(KERN_CRIT "%s:err at dccp_wait_for_ccid"
+                                                 " %d\n", __FUNCTION__, err);
+                                dump_stack();
+                        }
+                }
 
-        if (err == 0) {
-                struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
-                const int len = skb->len;
+                skb_dequeue(&sk->sk_write_queue);
+                if (err == 0) {
+                        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 */
-                        inet_csk_schedule_ack(sk);
-                        inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+                        if (sk->sk_state == DCCP_PARTOPEN) {
+                                /* See 8.1.5.  Handshake Completion */
+                                inet_csk_schedule_ack(sk);
+                                inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
                                                   inet_csk(sk)->icsk_rto,
                                                   DCCP_RTO_MAX);
-                        dcb->dccpd_type = DCCP_PKT_DATAACK;
-                } else if (dccp_ack_pending(sk))
-                        dcb->dccpd_type = DCCP_PKT_DATAACK;
-                else
-                        dcb->dccpd_type = DCCP_PKT_DATA;
-
-                err = dccp_transmit_skb(sk, skb);
-                ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
-        } else
-                kfree_skb(skb);
-
-        return err;
+                                dcb->dccpd_type = DCCP_PKT_DATAACK;
+                        } else if (dccp_ack_pending(sk))
+                                dcb->dccpd_type = DCCP_PKT_DATAACK;
+                        else
+                                dcb->dccpd_type = DCCP_PKT_DATA;
+
+                        err = dccp_transmit_skb(sk, skb);
+                        ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
+                        if (err) {
+                                printk(KERN_CRIT "%s:err from "
+                                                 "ccid_hc_tx_packet_sent %d\n",
+                                                 __FUNCTION__, err);
+                                dump_stack();
+                        }
+                } else
+                        kfree(skb);
+        }
 }
 
 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
@@ -426,6 +461,9 @@ static inline void dccp_connect_init(struct sock *sk)
         dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
 
         icsk->icsk_retransmits = 0;
+        init_timer(&dp->dccps_xmit_timer);
+        dp->dccps_xmit_timer.data = (unsigned long)sk;
+        dp->dccps_xmit_timer.function = dccp_write_xmit_timer;
 }
 
 int dccp_connect(struct sock *sk)
@@ -560,8 +598,10 @@ void dccp_send_close(struct sock *sk, const int active)
                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
 
         if (active) {
+                dccp_write_xmit(sk, 1);
                 dccp_skb_entail(sk, skb);
                 dccp_transmit_skb(sk, skb_clone(skb, prio));
+                /* FIXME do we need a retransmit timer here? */
         } else
                 dccp_transmit_skb(sk, skb);
 }
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 6f14bb5a28d4..962df0ea31aa 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -662,17 +662,8 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         if (rc != 0)
                 goto out_discard;
 
-        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
-         *     an algorith similar to tcp_sendmsg, where the main difference
-         *     is that in DCCP we have to respect packet boundaries, so
-         *     no coalescing of skbs.
-         *
-         *     This bug was _quickly_ found & fixed by just looking at an OSTRA
-         *     generated callgraph 8) -acme
-         */
+        skb_queue_tail(&sk->sk_write_queue, skb);
+        dccp_write_xmit(sk,0);
 out_release:
         release_sock(sk);
         return rc ? : len;
@@ -846,6 +837,7 @@ static int dccp_close_state(struct sock *sk)
 
 void dccp_close(struct sock *sk, long timeout)
 {
+        struct dccp_sock *dp = dccp_sk(sk);
         struct sk_buff *skb;
         int state;
 
@@ -862,6 +854,8 @@ void dccp_close(struct sock *sk, long timeout)
                 goto adjudge_to_death;
         }
 
+        sk_stop_timer(sk, &dp->dccps_xmit_timer);
+
         /*
          * We need to flush the recv. buffs.  We do this only on the
          * descriptor close, not protocol-sourced closes, because the