I am resubmitting this since the original patch had a bug: * original patch was on http://www.mail-archive.com/dccp@xxxxxxxxxxxxxxx/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 <gerrit@xxxxxxxxxxxxxx> --- 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; - To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
