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dccp: Extend CCID packet dequeueing interface

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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>
This commit is contained in:
Gerrit Renker
2010-10-27 19:16:26 +00:00
committed by David S. Miller
parent fe84f4140f
commit dc841e30ea
3 changed files with 89 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
net/dccp/timer.c
View File

@@ -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);
}