I am resubmitting this since the original patch had a bug:
* original patch was on
http://www.mail-archive.com/[email protected]/msg01937.html
* when applying scaled_div(1, hcrx->ccid3hcrx_pinv) to an unitialised `pinv',
there would have been a divide-by-zero exception (BUG)
* replaced by explicit test, return ~0U instead (as in RFC 4342, sec. 8.5)
* also moved the initialisation to where it is actually being used.
-------------------------------------> Patch v2
<-------------------------------------
[CCID 3]: Use a function to update p_inv, and p is never used
This patch
1) concentrates previously scattered computation of p_inv into one function;
2) removes the `p' element of the CCID3 RX sock (it is redundant);
3) makes the tfrc_rx_info structure standalone, only used on demand.
The reason for (2) is that the code essentially only uses p_inv = 1/p. It does
not
need p, since all the relevant information is already in p_inv.
The motivation for (3) is that the embedded info structure will not be used
often,
so that the extra cost of keeping p in synch with p_inv (which has to be done at
each packet reception) is overhead most of the time.
Advantages that this buys:
--------------------------
* the RX sock loses further weight;
* computation of p_inv is no longer scattered in different places;
* not having to keep p in sync with p_inv speeds up computation
(important, as p_inv has to be recomputed for each new data packet);
* several test cases can now be removed since all is in one function;
* the send_feedback and packet_recv code becomes simpler.
Signed-off-by: Gerrit Renker <[EMAIL PROTECTED]>
---
net/dccp/ccids/ccid3.c | 13 +++++++++----
net/dccp/ccids/ccid3.h | 11 ++++-------
2 files changed, 13 insertions(+), 11 deletions(-)
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -141,12 +141,11 @@ enum ccid3_fback_type {
/** struct ccid3_hc_rx_sock - CCID3 receiver half-connection socket
*
- * @ccid3hcrx_x_recv - Receiver estimate of send rate (RFC 3448 4.3)
- * @ccid3hcrx_rtt - Receiver estimate of rtt (non-standard)
- * @ccid3hcrx_p - current loss event rate (RFC 3448 5.4)
* @ccid3hcrx_last_counter - Tracks window counter (RFC 4342, 8.1)
* @ccid3hcrx_state - Receiver state, one of %ccid3_hc_rx_states
* @ccid3hcrx_bytes_recv - Total sum of DCCP payload bytes
+ * @ccid3hcrx_x_recv - Receiver estimate of send rate (RFC 3448, sec. 4.3)
+ * @ccid3hcrx_rtt - Receiver estimate of RTT
* @ccid3hcrx_last_feedback - Time at which last feedback was sent
* @ccid3hcrx_hist - Packet history, exported by TFRC module
* @ccid3hcrx_li_hist - Loss Interval database, exported by TFRC module
@@ -154,13 +153,11 @@ enum ccid3_fback_type {
* @ccid3hcrx_pinv - Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
*/
struct ccid3_hc_rx_sock {
- struct tfrc_rx_info ccid3hcrx_tfrc;
-#define ccid3hcrx_x_recv ccid3hcrx_tfrc.tfrcrx_x_recv
-#define ccid3hcrx_rtt ccid3hcrx_tfrc.tfrcrx_rtt
-#define ccid3hcrx_p ccid3hcrx_tfrc.tfrcrx_p
u8 ccid3hcrx_last_counter:4;
enum ccid3_hc_rx_states ccid3hcrx_state:8;
u32 ccid3hcrx_bytes_recv;
+ u32 ccid3hcrx_x_recv;
+ u32 ccid3hcrx_rtt;
ktime_t ccid3hcrx_last_feedback;
struct tfrc_rx_hist ccid3hcrx_hist;
struct tfrc_loss_hist ccid3hcrx_li_hist;
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -902,17 +902,22 @@ static int ccid3_hc_rx_getsockopt(struct
{
const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
const void *val;
+ struct tfrc_rx_info rx_info;
- /* Listen socks doesn't have a private CCID block */
+ /* Listen socks don't have a private CCID block */
if (sk->sk_state == DCCP_LISTEN)
return -EINVAL;
switch (optname) {
case DCCP_SOCKOPT_CCID_RX_INFO:
- if (len < sizeof(hcrx->ccid3hcrx_tfrc))
+ if (len < sizeof(rx_info))
return -EINVAL;
- len = sizeof(hcrx->ccid3hcrx_tfrc);
- val = &hcrx->ccid3hcrx_tfrc;
+ len = sizeof(rx_info);
+ val = &rx_info;
+ rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv;
+ rx_info.tfrcrx_rtt = hcrx->ccid3hcrx_rtt;
+ rx_info.tfrcrx_p = hcrx->ccid3hcrx_pinv == 0? ~0U
+ : scaled_div(1, hcrx->ccid3hcrx_pinv);
break;
default:
return -ENOPROTOOPT;
-
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