[TFRC]: Let calling module compute First Loss Interval
TFRC [RFC 3448] requires a synthetic value of the first loss interval length.
Since computing this value requires access to the internals of the calling
module (parameters s, RTT, and X_recv), it is better to let the calling module
compute the First Loss Interval length.
Therefore, to highlight this, the function has been renamed into
`ccid3_first_li' (due to a max line length of 80 characters); the code has
been arranged and comments tidied up, but no functional change results.
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/ccids/ccid3.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -812,11 +812,16 @@ static int ccid3_hc_rx_insert_options(st
return 0;
}
-/* calculate first loss interval
+/** ccid3_first_li - Implements [RFC 3448, 6.3.1]
*
- * returns estimated loss interval in usecs */
-
-static u32 ccid3_hc_rx_calc_first_li(struct sock *sk)
+ * Determine the length of the first loss interval via inverse lookup.
+ * Assume that X_recv can be computed by the throughput equation
+ * s
+ * X_recv = --------
+ * R * fval
+ * Find some p such that f(p) = fval; return 1/p (scaled).
+ */
+static u32 ccid3_first_li(struct sock *sk)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
u32 x_recv, p;
@@ -824,14 +829,6 @@ static u32 ccid3_hc_rx_calc_first_li(str
struct timeval tstamp;
u64 fval;
- /*
- * Determine the length of the first loss interval via inverse lookup.
- * Assume that X_recv can be computed by the throughput equation
- * s
- * X_recv = --------
- * R * fval
- * Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
- */
if (hcrx->ccid3hcrx_rtt == 0) {
DCCP_WARN("No RTT estimate available, using 0.2sec fallback\n");
hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
@@ -842,7 +839,7 @@ static u32 ccid3_hc_rx_calc_first_li(str
DCCP_BUG_ON(delta <= 0);
x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
- if (x_recv == 0) { /* would also trigger divide-by-zero */
+ if (x_recv == 0) {
DCCP_WARN("X_recv==0\n");
if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
DCCP_BUG("stored value of X_recv is zero");
-
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