[DCCP] ccid3: Consolidate timer resets

This patch concerns updating the value of the nofeedback timer when no feedback
has been received so far.

Since in this case the value of R is still undefined according to [RFC 3448,
4.2], we can not perform step (3) of [RFC 3448, 4.3].  A clarification is
provided in [RFC 4342, sec. 5], which states that in these cases the nofeedback
timer (still) expires "after two seconds".

Many thanks to Ian McDonald for pointing this out and providing the
clarification.

The patch
  * implements [RFC 4342, sec. 5] with regard to the above case
  * consolidates handling timer restart by
	- adding an appropriate jump label and
	- initialising the timeout value

Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 6777a7f33a9a00a8e73833650260ce6370c9bf35..9297fca7868305a40bbf35a2c6ec1cd4a8ea98df 100644 (file)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -154,16 +154,14 @@ static void ccid3_hc_tx_update_x(struct sock *sk)
 static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
 {
        struct sock *sk = (struct sock *)data;
-       unsigned long next_tmout = 0;
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+       unsigned long next_tmout = USEC_PER_SEC / 5;
 
        bh_lock_sock(sk);
        if (sock_owned_by_user(sk)) {
                /* Try again later. */
                /* XXX: set some sensible MIB */
-               sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
-                              jiffies + HZ / 5);
-               goto out;
+               goto restart_timer;
        }
 
        ccid3_pr_debug("%s, sk=%p, state=%s\n", dccp_role(sk), sk,
@@ -183,9 +181,9 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
                               dccp_role(sk), sk,
                               ccid3_tx_state_name(hctx->ccid3hctx_state),
                               hctx->ccid3hctx_x);
-               next_tmout = max_t(u32, 2 * usecs_div(hctx->ccid3hctx_s,
-                                                     hctx->ccid3hctx_x),
-                                       TFRC_INITIAL_TIMEOUT);
+               /* The value of R is still undefined and so we can not recompute
+                * the timout value. Keep initial value as per [RFC 4342, 5]. */
+               next_tmout = TFRC_INITIAL_TIMEOUT;
                /*
                 * FIXME - not sure above calculation is correct. See section
                 * 5 of CCID3 11 should adjust tx_t_ipi and double that to
@@ -239,9 +237,11 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
                goto out;
        }
 
-       sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 
-                     jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout)));
        hctx->ccid3hctx_idle = 1;
+
+restart_timer:
+       sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+                          jiffies + usecs_to_jiffies(next_tmout));
 out:
        bh_unlock_sock(sk);
        sock_put(sk);

diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h
index 462165234ff6620d54d1688a6184efbd3387a01f..970921700ce35458e6cc67056a4086397386080e 100644 (file)
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -46,7 +46,7 @@
 #define TFRC_STD_PACKET_SIZE     256
 #define TFRC_MAX_PACKET_SIZE   65535
 
-/* Two seconds as per CCID3 spec */
+/* Two seconds as per RFC 3448 4.2 */
 #define TFRC_INITIAL_TIMEOUT      (2 * USEC_PER_SEC)
 
 /* In usecs - half the scheduling granularity as per RFC3448 4.6 */