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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2010-10-27 19:16:26 +0000
committerDavid S. Miller <davem@davemloft.net>2010-10-28 10:27:00 -0700
commitdc841e30eaea9f9f83c9ab1ee0b3ef9e5c95ce8a (patch)
tree921458d0ea02f1478dbac9305c1925dbea8c0dd9 /net
parentfe84f4140f0d24deca8591e38926b95cfd097e62 (diff)
downloadlinux-2.6.38-lt-ux500-dc841e30eaea9f9f83c9ab1ee0b3ef9e5c95ce8a.tar.gz
dccp: Extend CCID packet dequeueing interface
This extends the packet dequeuing interface of dccp_write_xmit() to allow 1. CCIDs to take care of timing when the next packet may be sent; 2. delayed sending (as before, with an inter-packet gap up to 65.535 seconds). The main purpose is to take CCID-2 out of its polling mode (when it is network- limited, it tries every millisecond to send, without interruption). The mode of operation for (2) is as follows: * new packet is enqueued via dccp_sendmsg() => dccp_write_xmit(), * ccid_hc_tx_send_packet() detects that it may not send (e.g. window full), * it signals this condition via `CCID_PACKET_WILL_DEQUEUE_LATER', * dccp_write_xmit() returns without further action; * after some time the wait-condition for CCID becomes true, * that CCID schedules the tasklet, * tasklet function calls ccid_hc_tx_send_packet() via dccp_write_xmit(), * since the wait-condition is now true, ccid_hc_tx_packet() returns "send now", * packet is sent, and possibly more (since dccp_write_xmit() loops). Code reuse: the taskled function calls dccp_write_xmit(), the timer function reduces to a wrapper around the same code. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/dccp/output.c118
-rw-r--r--net/dccp/timer.c25
2 files changed, 86 insertions, 57 deletions
diff --git a/net/dccp/output.c b/net/dccp/output.c
index a988fe9ffcb..11418a9a389 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -254,63 +254,89 @@ do_interrupted:
goto out;
}
+/**
+ * dccp_xmit_packet - Send data packet under control of CCID
+ * Transmits next-queued payload and informs CCID to account for the packet.
+ */
+static void dccp_xmit_packet(struct sock *sk)
+{
+ int err, len;
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct sk_buff *skb = skb_dequeue(&sk->sk_write_queue);
+
+ if (unlikely(skb == NULL))
+ return;
+ len = skb->len;
+
+ if (sk->sk_state == DCCP_PARTOPEN) {
+ const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD;
+ /*
+ * See 8.1.5 - Handshake Completion.
+ *
+ * For robustness we resend Confirm options until the client has
+ * entered OPEN. During the initial feature negotiation, the MPS
+ * is smaller than usual, reduced by the Change/Confirm options.
+ */
+ if (!list_empty(&dp->dccps_featneg) && len > cur_mps) {
+ DCCP_WARN("Payload too large (%d) for featneg.\n", len);
+ dccp_send_ack(sk);
+ dccp_feat_list_purge(&dp->dccps_featneg);
+ }
+
+ inet_csk_schedule_ack(sk);
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+ inet_csk(sk)->icsk_rto,
+ DCCP_RTO_MAX);
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK;
+ } else if (dccp_ack_pending(sk)) {
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK;
+ } else {
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATA;
+ }
+
+ err = dccp_transmit_skb(sk, skb);
+ if (err)
+ dccp_pr_debug("transmit_skb() returned err=%d\n", err);
+ /*
+ * Register this one as sent even if an error occurred. To the remote
+ * end a local packet drop is indistinguishable from network loss, i.e.
+ * any local drop will eventually be reported via receiver feedback.
+ */
+ ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len);
+}
+
void dccp_write_xmit(struct sock *sk, int block)
{
struct dccp_sock *dp = dccp_sk(sk);
struct sk_buff *skb;
while ((skb = skb_peek(&sk->sk_write_queue))) {
- int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
+ int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
- if (err > 0) {
+ switch (ccid_packet_dequeue_eval(rc)) {
+ case CCID_PACKET_WILL_DEQUEUE_LATER:
+ return;
+ case CCID_PACKET_DELAY:
if (!block) {
sk_reset_timer(sk, &dp->dccps_xmit_timer,
- msecs_to_jiffies(err)+jiffies);
+ msecs_to_jiffies(rc)+jiffies);
+ return;
+ }
+ rc = dccp_wait_for_ccid(sk, skb, rc);
+ if (rc && rc != -EINTR) {
+ DCCP_BUG("err=%d after dccp_wait_for_ccid", rc);
+ skb_dequeue(&sk->sk_write_queue);
+ kfree_skb(skb);
break;
- } else
- err = dccp_wait_for_ccid(sk, skb, err);
- if (err && err != -EINTR)
- DCCP_BUG("err=%d after dccp_wait_for_ccid", err);
- }
-
- 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) {
- const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD;
- /*
- * See 8.1.5 - Handshake Completion.
- *
- * For robustness we resend Confirm options until the client has
- * entered OPEN. During the initial feature negotiation, the MPS
- * is smaller than usual, reduced by the Change/Confirm options.
- */
- if (!list_empty(&dp->dccps_featneg) && len > cur_mps) {
- DCCP_WARN("Payload too large (%d) for featneg.\n", len);
- dccp_send_ack(sk);
- dccp_feat_list_purge(&dp->dccps_featneg);
- }
-
- 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, len);
- if (err)
- DCCP_BUG("err=%d after ccid_hc_tx_packet_sent",
- err);
- } else {
- dccp_pr_debug("packet discarded due to err=%d\n", err);
+ }
+ /* fall through */
+ case CCID_PACKET_SEND_AT_ONCE:
+ dccp_xmit_packet(sk);
+ break;
+ case CCID_PACKET_ERR:
+ skb_dequeue(&sk->sk_write_queue);
kfree_skb(skb);
+ dccp_pr_debug("packet discarded due to err=%d\n", rc);
}
}
}
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index 1a9aa05d4dc..916f9d1dab3 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -237,32 +237,35 @@ out:
sock_put(sk);
}
-/* Transmit-delay timer: used by the CCIDs to delay actual send time */
-static void dccp_write_xmit_timer(unsigned long data)
+/**
+ * dccp_write_xmitlet - Workhorse for CCID packet dequeueing interface
+ * See the comments above %ccid_dequeueing_decision for supported modes.
+ */
+static void dccp_write_xmitlet(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);
+ sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1);
else
dccp_write_xmit(sk, 0);
bh_unlock_sock(sk);
- sock_put(sk);
}
-static void dccp_init_write_xmit_timer(struct sock *sk)
+static void dccp_write_xmit_timer(unsigned long data)
{
- struct dccp_sock *dp = dccp_sk(sk);
-
- setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer,
- (unsigned long)sk);
+ dccp_write_xmitlet(data);
+ sock_put((struct sock *)data);
}
void dccp_init_xmit_timers(struct sock *sk)
{
- dccp_init_write_xmit_timer(sk);
+ struct dccp_sock *dp = dccp_sk(sk);
+
+ tasklet_init(&dp->dccps_xmitlet, dccp_write_xmitlet, (unsigned long)sk);
+ setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer,
+ (unsigned long)sk);
inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
&dccp_keepalive_timer);
}