[CCID 3]: Consolidate timer resets
The specification in [RFC 3448, 4.4, step (3)] is impossible to
implement: when no feedback has been received, the value of RTT
is undefined as per [RFC 3448, 4.2]. Hence we can not set the
timeout value to max(4*R, 2*s/X) as step (3) suggests.
The most reasonable solution is to remain at the initial timeout
value of 2 seconds, as per [RFC 3448, 4.2] - until an estimate
for R has been computed.
The patch also consolidates handling timer restart by adding
an appropriate jump label and initialising the timeout value.
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/ccids/ccid3.c | 18 +++++++++---------
net/dccp/ccids/ccid3.h | 2 +-
2 files changed, 10 insertions(+), 10 deletions(-)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -172,16 +172,14 @@ static inline void ccid3_hc_tx_update_s(
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,
@@ -201,9 +199,9 @@ static void ccid3_hc_tx_no_feedback_time
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);
+ /* We cannot restart the timer as per [RFC 3448, 4.4] step (3),
+ * since RTT is still undefined. We keep the previous value. */
+ 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
@@ -257,9 +255,11 @@ static void ccid3_hc_tx_no_feedback_time
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);
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -42,7 +42,7 @@
#include <linux/tfrc.h>
#include "../ccid.h"
-/* 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 */
-
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