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439 lines
13 KiB
439 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (c) 2007 The University of Aberdeen, Scotland, UK |
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* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. |
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* |
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* An implementation of the DCCP protocol |
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* |
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* This code has been developed by the University of Waikato WAND |
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* research group. For further information please see https://www.wand.net.nz/ |
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* or e-mail Ian McDonald - [email protected] |
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* |
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* This code also uses code from Lulea University, rereleased as GPL by its |
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* authors: |
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* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon |
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* |
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* Changes to meet Linux coding standards, to make it meet latest ccid3 draft |
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* and to make it work as a loadable module in the DCCP stack written by |
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* Arnaldo Carvalho de Melo <[email protected]>. |
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* |
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* Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]> |
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*/ |
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#include <linux/string.h> |
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#include <linux/slab.h> |
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#include "packet_history.h" |
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#include "../../dccp.h" |
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/* |
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* Transmitter History Routines |
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*/ |
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static struct kmem_cache *tfrc_tx_hist_slab; |
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int __init tfrc_tx_packet_history_init(void) |
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{ |
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tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist", |
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sizeof(struct tfrc_tx_hist_entry), |
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0, SLAB_HWCACHE_ALIGN, NULL); |
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return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0; |
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} |
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void tfrc_tx_packet_history_exit(void) |
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{ |
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if (tfrc_tx_hist_slab != NULL) { |
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kmem_cache_destroy(tfrc_tx_hist_slab); |
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tfrc_tx_hist_slab = NULL; |
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} |
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} |
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int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno) |
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{ |
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struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any()); |
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if (entry == NULL) |
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return -ENOBUFS; |
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entry->seqno = seqno; |
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entry->stamp = ktime_get_real(); |
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entry->next = *headp; |
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*headp = entry; |
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return 0; |
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} |
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void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp) |
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{ |
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struct tfrc_tx_hist_entry *head = *headp; |
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while (head != NULL) { |
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struct tfrc_tx_hist_entry *next = head->next; |
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kmem_cache_free(tfrc_tx_hist_slab, head); |
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head = next; |
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} |
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*headp = NULL; |
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} |
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/* |
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* Receiver History Routines |
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*/ |
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static struct kmem_cache *tfrc_rx_hist_slab; |
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int __init tfrc_rx_packet_history_init(void) |
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{ |
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tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache", |
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sizeof(struct tfrc_rx_hist_entry), |
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0, SLAB_HWCACHE_ALIGN, NULL); |
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return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0; |
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} |
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void tfrc_rx_packet_history_exit(void) |
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{ |
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if (tfrc_rx_hist_slab != NULL) { |
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kmem_cache_destroy(tfrc_rx_hist_slab); |
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tfrc_rx_hist_slab = NULL; |
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} |
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} |
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static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry, |
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const struct sk_buff *skb, |
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const u64 ndp) |
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{ |
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const struct dccp_hdr *dh = dccp_hdr(skb); |
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entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq; |
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entry->tfrchrx_ccval = dh->dccph_ccval; |
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entry->tfrchrx_type = dh->dccph_type; |
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entry->tfrchrx_ndp = ndp; |
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entry->tfrchrx_tstamp = ktime_get_real(); |
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} |
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void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, |
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const struct sk_buff *skb, |
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const u64 ndp) |
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{ |
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struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h); |
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tfrc_rx_hist_entry_from_skb(entry, skb, ndp); |
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} |
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/* has the packet contained in skb been seen before? */ |
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int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb) |
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{ |
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const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq; |
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int i; |
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if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0) |
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return 1; |
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for (i = 1; i <= h->loss_count; i++) |
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if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq) |
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return 1; |
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return 0; |
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} |
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static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b) |
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{ |
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const u8 idx_a = tfrc_rx_hist_index(h, a), |
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idx_b = tfrc_rx_hist_index(h, b); |
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swap(h->ring[idx_a], h->ring[idx_b]); |
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} |
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/* |
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* Private helper functions for loss detection. |
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* |
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* In the descriptions, `Si' refers to the sequence number of entry number i, |
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* whose NDP count is `Ni' (lower case is used for variables). |
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* Note: All __xxx_loss functions expect that a test against duplicates has been |
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* performed already: the seqno of the skb must not be less than the seqno |
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* of loss_prev; and it must not equal that of any valid history entry. |
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*/ |
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static void __do_track_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u64 n1) |
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{ |
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u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, |
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s1 = DCCP_SKB_CB(skb)->dccpd_seq; |
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if (!dccp_loss_free(s0, s1, n1)) { /* gap between S0 and S1 */ |
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h->loss_count = 1; |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n1); |
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} |
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} |
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static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2) |
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{ |
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u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, |
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s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, |
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s2 = DCCP_SKB_CB(skb)->dccpd_seq; |
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if (likely(dccp_delta_seqno(s1, s2) > 0)) { /* S1 < S2 */ |
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h->loss_count = 2; |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2); |
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return; |
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} |
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/* S0 < S2 < S1 */ |
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if (dccp_loss_free(s0, s2, n2)) { |
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u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp; |
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if (dccp_loss_free(s2, s1, n1)) { |
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/* hole is filled: S0, S2, and S1 are consecutive */ |
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h->loss_count = 0; |
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h->loss_start = tfrc_rx_hist_index(h, 1); |
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} else |
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/* gap between S2 and S1: just update loss_prev */ |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2); |
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} else { /* gap between S0 and S2 */ |
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/* |
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* Reorder history to insert S2 between S0 and S1 |
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*/ |
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tfrc_rx_hist_swap(h, 0, 3); |
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h->loss_start = tfrc_rx_hist_index(h, 3); |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2); |
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h->loss_count = 2; |
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} |
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} |
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/* return 1 if a new loss event has been identified */ |
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static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3) |
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{ |
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u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, |
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s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, |
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s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, |
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s3 = DCCP_SKB_CB(skb)->dccpd_seq; |
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if (likely(dccp_delta_seqno(s2, s3) > 0)) { /* S2 < S3 */ |
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h->loss_count = 3; |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3); |
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return 1; |
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} |
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/* S3 < S2 */ |
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if (dccp_delta_seqno(s1, s3) > 0) { /* S1 < S3 < S2 */ |
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/* |
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* Reorder history to insert S3 between S1 and S2 |
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*/ |
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tfrc_rx_hist_swap(h, 2, 3); |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3); |
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h->loss_count = 3; |
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return 1; |
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} |
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/* S0 < S3 < S1 */ |
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if (dccp_loss_free(s0, s3, n3)) { |
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u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp; |
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if (dccp_loss_free(s3, s1, n1)) { |
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/* hole between S0 and S1 filled by S3 */ |
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u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp; |
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if (dccp_loss_free(s1, s2, n2)) { |
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/* entire hole filled by S0, S3, S1, S2 */ |
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h->loss_start = tfrc_rx_hist_index(h, 2); |
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h->loss_count = 0; |
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} else { |
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/* gap remains between S1 and S2 */ |
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h->loss_start = tfrc_rx_hist_index(h, 1); |
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h->loss_count = 1; |
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} |
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} else /* gap exists between S3 and S1, loss_count stays at 2 */ |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3); |
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return 0; |
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} |
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/* |
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* The remaining case: S0 < S3 < S1 < S2; gap between S0 and S3 |
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* Reorder history to insert S3 between S0 and S1. |
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*/ |
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tfrc_rx_hist_swap(h, 0, 3); |
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h->loss_start = tfrc_rx_hist_index(h, 3); |
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3); |
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h->loss_count = 3; |
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return 1; |
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} |
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/* recycle RX history records to continue loss detection if necessary */ |
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static void __three_after_loss(struct tfrc_rx_hist *h) |
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{ |
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/* |
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* At this stage we know already that there is a gap between S0 and S1 |
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* (since S0 was the highest sequence number received before detecting |
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* the loss). To recycle the loss record, it is thus only necessary to |
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* check for other possible gaps between S1/S2 and between S2/S3. |
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*/ |
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u64 s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, |
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s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, |
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s3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_seqno; |
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u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp, |
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n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp; |
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if (dccp_loss_free(s1, s2, n2)) { |
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if (dccp_loss_free(s2, s3, n3)) { |
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/* no gap between S2 and S3: entire hole is filled */ |
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h->loss_start = tfrc_rx_hist_index(h, 3); |
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h->loss_count = 0; |
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} else { |
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/* gap between S2 and S3 */ |
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h->loss_start = tfrc_rx_hist_index(h, 2); |
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h->loss_count = 1; |
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} |
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} else { /* gap between S1 and S2 */ |
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h->loss_start = tfrc_rx_hist_index(h, 1); |
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h->loss_count = 2; |
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} |
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} |
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/** |
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* tfrc_rx_handle_loss - Loss detection and further processing |
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* @h: The non-empty RX history object |
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* @lh: Loss Intervals database to update |
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* @skb: Currently received packet |
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* @ndp: The NDP count belonging to @skb |
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* @calc_first_li: Caller-dependent computation of first loss interval in @lh |
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* @sk: Used by @calc_first_li (see tfrc_lh_interval_add) |
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* |
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* Chooses action according to pending loss, updates LI database when a new |
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* loss was detected, and does required post-processing. Returns 1 when caller |
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* should send feedback, 0 otherwise. |
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* Since it also takes care of reordering during loss detection and updates the |
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* records accordingly, the caller should not perform any more RX history |
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* operations when loss_count is greater than 0 after calling this function. |
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*/ |
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int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, |
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struct tfrc_loss_hist *lh, |
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struct sk_buff *skb, const u64 ndp, |
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u32 (*calc_first_li)(struct sock *), struct sock *sk) |
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{ |
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int is_new_loss = 0; |
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if (h->loss_count == 0) { |
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__do_track_loss(h, skb, ndp); |
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} else if (h->loss_count == 1) { |
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__one_after_loss(h, skb, ndp); |
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} else if (h->loss_count != 2) { |
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DCCP_BUG("invalid loss_count %d", h->loss_count); |
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} else if (__two_after_loss(h, skb, ndp)) { |
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/* |
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* Update Loss Interval database and recycle RX records |
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*/ |
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is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk); |
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__three_after_loss(h); |
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} |
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return is_new_loss; |
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} |
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int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h) |
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{ |
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int i; |
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for (i = 0; i <= TFRC_NDUPACK; i++) { |
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h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC); |
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if (h->ring[i] == NULL) |
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goto out_free; |
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} |
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h->loss_count = h->loss_start = 0; |
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return 0; |
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out_free: |
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while (i-- != 0) { |
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kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); |
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h->ring[i] = NULL; |
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} |
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return -ENOBUFS; |
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} |
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void tfrc_rx_hist_purge(struct tfrc_rx_hist *h) |
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{ |
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int i; |
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for (i = 0; i <= TFRC_NDUPACK; ++i) |
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if (h->ring[i] != NULL) { |
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kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); |
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h->ring[i] = NULL; |
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} |
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} |
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/** |
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* tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against |
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* @h: The non-empty RX history object |
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*/ |
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static inline struct tfrc_rx_hist_entry * |
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tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h) |
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{ |
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return h->ring[0]; |
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} |
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/** |
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* tfrc_rx_hist_rtt_prev_s - previously suitable (wrt rtt_last_s) RTT-sampling entry |
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* @h: The non-empty RX history object |
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*/ |
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static inline struct tfrc_rx_hist_entry * |
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tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h) |
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{ |
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return h->ring[h->rtt_sample_prev]; |
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} |
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/** |
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* tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal |
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* @h: receive histogram |
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* @skb: packet containing timestamp. |
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* |
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* Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able |
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* to compute a sample with given data - calling function should check this. |
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*/ |
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u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb) |
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{ |
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u32 sample = 0, |
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delta_v = SUB16(dccp_hdr(skb)->dccph_ccval, |
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tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); |
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if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */ |
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if (h->rtt_sample_prev == 2) { /* previous candidate stored */ |
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sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval, |
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tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); |
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if (sample) |
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sample = 4 / sample * |
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ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp, |
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tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp); |
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else /* |
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* FIXME: This condition is in principle not |
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* possible but occurs when CCID is used for |
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* two-way data traffic. I have tried to trace |
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* it, but the cause does not seem to be here. |
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*/ |
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DCCP_BUG("please report to [email protected]" |
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" => prev = %u, last = %u", |
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tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval, |
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tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); |
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} else if (delta_v < 1) { |
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h->rtt_sample_prev = 1; |
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goto keep_ref_for_next_time; |
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} |
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} else if (delta_v == 4) /* optimal match */ |
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sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp)); |
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else { /* suboptimal match */ |
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h->rtt_sample_prev = 2; |
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goto keep_ref_for_next_time; |
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} |
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if (unlikely(sample > DCCP_SANE_RTT_MAX)) { |
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DCCP_WARN("RTT sample %u too large, using max\n", sample); |
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sample = DCCP_SANE_RTT_MAX; |
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} |
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h->rtt_sample_prev = 0; /* use current entry as next reference */ |
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keep_ref_for_next_time: |
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return sample; |
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}
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