diff options
Diffstat (limited to 'net/dccp/ccids/lib/loss_interval.c')
| -rw-r--r-- | net/dccp/ccids/lib/loss_interval.c | 161 |
1 files changed, 156 insertions, 5 deletions
diff --git a/net/dccp/ccids/lib/loss_interval.c b/net/dccp/ccids/lib/loss_interval.c index c0a933a1d28e..39980d1f5352 100644 --- a/net/dccp/ccids/lib/loss_interval.c +++ b/net/dccp/ccids/lib/loss_interval.c @@ -1,6 +1,7 @@ /* * net/dccp/ccids/lib/loss_interval.c * + * Copyright (c) 2007 The University of Aberdeen, Scotland, UK * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz> * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br> @@ -10,12 +11,7 @@ * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ - -#include <linux/module.h> #include <net/sock.h> -#include "../../dccp.h" -#include "loss_interval.h" -#include "packet_history.h" #include "tfrc.h" #define DCCP_LI_HIST_IVAL_F_LENGTH 8 @@ -27,6 +23,54 @@ struct dccp_li_hist_entry { u32 dccplih_interval; }; +static struct kmem_cache *tfrc_lh_slab __read_mostly; +/* Loss Interval weights from [RFC 3448, 5.4], scaled by 10 */ +static const int tfrc_lh_weights[NINTERVAL] = { 10, 10, 10, 10, 8, 6, 4, 2 }; + +/* implements LIFO semantics on the array */ +static inline u8 LIH_INDEX(const u8 ctr) +{ + return (LIH_SIZE - 1 - (ctr % LIH_SIZE)); +} + +/* the `counter' index always points at the next entry to be populated */ +static inline struct tfrc_loss_interval *tfrc_lh_peek(struct tfrc_loss_hist *lh) +{ + return lh->counter ? lh->ring[LIH_INDEX(lh->counter - 1)] : NULL; +} + +/* given i with 0 <= i <= k, return I_i as per the rfc3448bis notation */ +static inline u32 tfrc_lh_get_interval(struct tfrc_loss_hist *lh, const u8 i) +{ + BUG_ON(i >= lh->counter); + return lh->ring[LIH_INDEX(lh->counter - i - 1)]->li_length; +} + +/* + * On-demand allocation and de-allocation of entries + */ +static struct tfrc_loss_interval *tfrc_lh_demand_next(struct tfrc_loss_hist *lh) +{ + if (lh->ring[LIH_INDEX(lh->counter)] == NULL) + lh->ring[LIH_INDEX(lh->counter)] = kmem_cache_alloc(tfrc_lh_slab, + GFP_ATOMIC); + return lh->ring[LIH_INDEX(lh->counter)]; +} + +void tfrc_lh_cleanup(struct tfrc_loss_hist *lh) +{ + if (!tfrc_lh_is_initialised(lh)) + return; + + for (lh->counter = 0; lh->counter < LIH_SIZE; lh->counter++) + if (lh->ring[LIH_INDEX(lh->counter)] != NULL) { + kmem_cache_free(tfrc_lh_slab, + lh->ring[LIH_INDEX(lh->counter)]); + lh->ring[LIH_INDEX(lh->counter)] = NULL; + } +} +EXPORT_SYMBOL_GPL(tfrc_lh_cleanup); + static struct kmem_cache *dccp_li_cachep __read_mostly; static inline struct dccp_li_hist_entry *dccp_li_hist_entry_new(const gfp_t prio) @@ -98,6 +142,65 @@ u32 dccp_li_hist_calc_i_mean(struct list_head *list) EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean); +static void tfrc_lh_calc_i_mean(struct tfrc_loss_hist *lh) +{ + u32 i_i, i_tot0 = 0, i_tot1 = 0, w_tot = 0; + int i, k = tfrc_lh_length(lh) - 1; /* k is as in rfc3448bis, 5.4 */ + + for (i=0; i <= k; i++) { + i_i = tfrc_lh_get_interval(lh, i); + + if (i < k) { + i_tot0 += i_i * tfrc_lh_weights[i]; + w_tot += tfrc_lh_weights[i]; + } + if (i > 0) + i_tot1 += i_i * tfrc_lh_weights[i-1]; + } + + BUG_ON(w_tot == 0); + lh->i_mean = max(i_tot0, i_tot1) / w_tot; +} + +/** + * tfrc_lh_update_i_mean - Update the `open' loss interval I_0 + * For recomputing p: returns `true' if p > p_prev <=> 1/p < 1/p_prev + */ +u8 tfrc_lh_update_i_mean(struct tfrc_loss_hist *lh, struct sk_buff *skb) +{ + struct tfrc_loss_interval *cur = tfrc_lh_peek(lh); + u32 old_i_mean = lh->i_mean; + s64 length; + + if (cur == NULL) /* not initialised */ + return 0; + + length = dccp_delta_seqno(cur->li_seqno, DCCP_SKB_CB(skb)->dccpd_seq); + + if (length - cur->li_length <= 0) /* duplicate or reordered */ + return 0; + + if (SUB16(dccp_hdr(skb)->dccph_ccval, cur->li_ccval) > 4) + /* + * Implements RFC 4342, 10.2: + * If a packet S (skb) exists whose seqno comes `after' the one + * starting the current loss interval (cur) and if the modulo-16 + * distance from C(cur) to C(S) is greater than 4, consider all + * subsequent packets as belonging to a new loss interval. This + * test is necessary since CCVal may wrap between intervals. + */ + cur->li_is_closed = 1; + + if (tfrc_lh_length(lh) == 1) /* due to RFC 3448, 6.3.1 */ + return 0; + + cur->li_length = length; + tfrc_lh_calc_i_mean(lh); + + return (lh->i_mean < old_i_mean); +} +EXPORT_SYMBOL_GPL(tfrc_lh_update_i_mean); + static int dccp_li_hist_interval_new(struct list_head *list, const u64 seq_loss, const u8 win_loss) { @@ -284,6 +387,54 @@ void dccp_li_update_li(struct sock *sk, EXPORT_SYMBOL_GPL(dccp_li_update_li); +/* Determine if `new_loss' does begin a new loss interval [RFC 4342, 10.2] */ +static inline u8 tfrc_lh_is_new_loss(struct tfrc_loss_interval *cur, + struct tfrc_rx_hist_entry *new_loss) +{ + return dccp_delta_seqno(cur->li_seqno, new_loss->tfrchrx_seqno) > 0 && + (cur->li_is_closed || SUB16(new_loss->tfrchrx_ccval, cur->li_ccval) > 4); +} + +/** tfrc_lh_interval_add - Insert new record into the Loss Interval database + * @lh: Loss Interval database + * @rh: Receive history containing a fresh loss event + * @calc_first_li: Caller-dependent routine to compute length of first interval + * @sk: Used by @calc_first_li in caller-specific way (subtyping) + * Updates I_mean and returns 1 if a new interval has in fact been added to @lh. + */ +int tfrc_lh_interval_add(struct tfrc_loss_hist *lh, struct tfrc_rx_hist *rh, + u32 (*calc_first_li)(struct sock *), struct sock *sk) +{ + struct tfrc_loss_interval *cur = tfrc_lh_peek(lh), *new; + + if (cur != NULL && !tfrc_lh_is_new_loss(cur, tfrc_rx_hist_loss_prev(rh))) + return 0; + + new = tfrc_lh_demand_next(lh); + if (unlikely(new == NULL)) { + DCCP_CRIT("Cannot allocate/add loss record."); + return 0; + } + + new->li_seqno = tfrc_rx_hist_loss_prev(rh)->tfrchrx_seqno; + new->li_ccval = tfrc_rx_hist_loss_prev(rh)->tfrchrx_ccval; + new->li_is_closed = 0; + + if (++lh->counter == 1) + lh->i_mean = new->li_length = (*calc_first_li)(sk); + else { + cur->li_length = dccp_delta_seqno(cur->li_seqno, new->li_seqno); + new->li_length = dccp_delta_seqno(new->li_seqno, + tfrc_rx_hist_last_rcv(rh)->tfrchrx_seqno); + if (lh->counter > (2*LIH_SIZE)) + lh->counter -= LIH_SIZE; + + tfrc_lh_calc_i_mean(lh); + } + return 1; +} +EXPORT_SYMBOL_GPL(tfrc_lh_interval_add); + int __init dccp_li_init(void) { dccp_li_cachep = kmem_cache_create("dccp_li_hist", |