[PATCH 21/25]: Wait for CCID

[PATCH 21/25]: Wait for CCID

[Gerrit Renker]

[DCCP]: Wait for CCID

This performs a minor optimisation: when ccid_hc_tx_send_packet returns
a value greater zero, then the same call previously was done again at the
begin of the while loop in dccp_wait_for_ccid.

This patch exploits the available information and schedule-timeouts directly
instead.

Documentation also added.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
---
 net/dccp/output.c |   34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -174,34 +174,38 @@ void dccp_write_space(struct sock *sk)
 
 /**
  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
- * @sk: socket to wait for
+ * @sk:    socket to wait for
+ * @skb:   current skb to pass on for waiting
+ * @delay: sleep timeout in milliseconds (> 0)
+ * This function is called by default when the socket is closed, and
+ * when a non-zero linger time is set on the socket. For consistency
  */
-static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb)
+static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb, int delay)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
 	DEFINE_WAIT(wait);
-	unsigned long delay;
+	unsigned long jiffdelay;
 	int rc;
 
-	while (1) {
+	do {
+		dccp_pr_debug("delayed send by %d msec\n", delay);
+		jiffdelay = msecs_to_jiffies(delay);
+
 		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 
+		sk->sk_write_pending++;
+		release_sock(sk);
+		schedule_timeout(jiffdelay);
+		lock_sock(sk);
+		sk->sk_write_pending--;
+
 		if (sk->sk_err)
 			goto do_error;
 		if (signal_pending(current))
 			goto do_interrupted;
 
 		rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
-		if (rc <= 0)
-			break;
-		dccp_pr_debug("delayed send by %d msec\n", rc);
-		delay = msecs_to_jiffies(rc);
-		sk->sk_write_pending++;
-		release_sock(sk);
-		schedule_timeout(delay);
-		lock_sock(sk);
-		sk->sk_write_pending--;
-	}
+	} while ((delay = rc) > 0);
 out:
 	finish_wait(sk->sk_sleep, &wait);
 	return rc;
@@ -228,7 +232,7 @@ void dccp_write_xmit(struct sock *sk, in
 						msecs_to_jiffies(err)+jiffies);
 				break;
 			} else
-				err = dccp_wait_for_ccid(sk, skb);
+				err = dccp_wait_for_ccid(sk, skb, err);
 			if (err && err != -EINTR)
 				DCCP_BUG("err=%d after dccp_wait_for_ccid", err);
 		}

Re: [PATCH 21/25]: Wait for CCID

[Ian McDonald]

On 3/22/07, Gerrit Renker <gerrit@erg.abdn.ac.uk> wrote:
> [DCCP]: Wait for CCID
>
> This performs a minor optimisation: when ccid_hc_tx_send_packet returns
> a value greater zero, then the same call previously was done again at the
> begin of the while loop in dccp_wait_for_ccid.
>
> This patch exploits the available information and schedule-timeouts directly
> instead.
>
> Documentation also added.
>
> Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

Great spotting. I had noticed that ccid_hc_tx_send_packet had been
getting called needlessly before and this should fix that.

Ian
-- 
Web: http://wand.net.nz/~iam4
Blog: http://iansblog.jandi.co.nz
WAND Network Research Group

Re: [PATCH 21/25]: Wait for CCID

[Gerrit Renker]

|  Great spotting.
Are you then ok if I add your Acked-by to this patch (it wasn't in your reply email)?

Re: [PATCH 21/25]: Wait for CCID

[Ian McDonald]

On 4/2/07, Gerrit Renker <gerrit@erg.abdn.ac.uk> wrote:
> |  Great spotting.
> Are you then ok if I add your Acked-by to this patch (it wasn't in your reply email)?
>
I'll do more than that as I know that code inside out...

Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>

-- 
Web: http://wand.net.nz/~iam4/
Blog: http://iansblog.jandi.co.nz
WAND Network Research Group