[CCID3]: Call sk->sk_write_space(sk) when receiving a feedback packet

This makes the send rate calculations behave way more closely to what
is specified, with the jitter previously seen on x and x_recv
disappearing completely on non lossy setups.

This resembles the tcp_data_snd_check code, that possibly we'll end up
using in DCCP as well, perhaps moving this code to
inet_connection_sock.

For now I'm doing the simplest implementation tho.

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

4 files changed, 20 insertions, 0 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index e22b0eefdbf9..7bf3b3a91e97 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -556,6 +556,11 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 /* remove all packets older than the one acked from history */
                 dccp_tx_hist_purge_older(ccid3_tx_hist,
                                          &hctx->ccid3hctx_hist, packet);
+                /*
+                 * As we have calculated new ipi, delta, t_nom it is possible that
+                 * we now can send a packet, so wake up dccp_wait_for_ccids.
+                 */
+                sk->sk_write_space(sk);
 
                 /*
                  * Schedule no feedback timer to expire in
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 5cd9e794bbe2..33456c0d5937 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -127,6 +127,7 @@ 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_space(struct sock *sk);
 
 extern void dccp_init_xmit_timers(struct sock *sk);
 static inline void dccp_clear_xmit_timers(struct sock *sk)
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 3cf2cbcdcafd..3fc75dbee4b8 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -1280,6 +1280,7 @@ static int dccp_v4_init_sock(struct sock *sk)
         dccp_init_xmit_timers(sk);
         inet_csk(sk)->icsk_rto = DCCP_TIMEOUT_INIT;
         sk->sk_state = DCCP_CLOSED;
+        sk->sk_write_space = dccp_write_space;
         dp->dccps_mss_cache = 536;
         dp->dccps_role = DCCP_ROLE_UNDEFINED;
 
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 116f6db5678d..28de157a4326 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -150,6 +150,19 @@ unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
         return mss_now;
 }
 
+void dccp_write_space(struct sock *sk)
+{
+        read_lock(&sk->sk_callback_lock);
+
+        if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+                wake_up_interruptible(sk->sk_sleep);
+        /* Should agree with poll, otherwise some programs break */
+        if (sock_writeable(sk))
+                sk_wake_async(sk, 2, POLL_OUT);
+
+        read_unlock(&sk->sk_callback_lock);
+}
+
 /**
  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
  * @sk: socket to wait for