/*
* net/dccp/packet_history.c
*
- * Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
+ * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
+ * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
*
* An implementation of the DCCP protocol
*
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
-#include <linux/module.h>
#include <linux/string.h>
-
+#include <linux/slab.h>
#include "packet_history.h"
+#include "../../dccp.h"
+
+/**
+ * tfrc_tx_hist_entry - Simple singly-linked TX history list
+ * @next: next oldest entry (LIFO order)
+ * @seqno: sequence number of this entry
+ * @stamp: send time of packet with sequence number @seqno
+ */
+struct tfrc_tx_hist_entry {
+ struct tfrc_tx_hist_entry *next;
+ u64 seqno;
+ ktime_t stamp;
+};
-struct dccp_rx_hist *dccp_rx_hist_new(const char *name)
+/*
+ * Transmitter History Routines
+ */
+static struct kmem_cache *tfrc_tx_hist_slab;
+
+int __init tfrc_tx_packet_history_init(void)
{
- struct dccp_rx_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
- static const char dccp_rx_hist_mask[] = "rx_hist_%s";
- char *slab_name;
-
- if (hist == NULL)
- goto out;
-
- slab_name = kmalloc(strlen(name) + sizeof(dccp_rx_hist_mask) - 1,
- GFP_ATOMIC);
- if (slab_name == NULL)
- goto out_free_hist;
-
- sprintf(slab_name, dccp_rx_hist_mask, name);
- hist->dccprxh_slab = kmem_cache_create(slab_name,
- sizeof(struct dccp_rx_hist_entry),
- 0, SLAB_HWCACHE_ALIGN,
- NULL, NULL);
- if (hist->dccprxh_slab == NULL)
- goto out_free_slab_name;
-out:
- return hist;
-out_free_slab_name:
- kfree(slab_name);
-out_free_hist:
- kfree(hist);
- hist = NULL;
- goto out;
+ tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist",
+ sizeof(struct tfrc_tx_hist_entry),
+ 0, SLAB_HWCACHE_ALIGN, NULL);
+ return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0;
}
-EXPORT_SYMBOL_GPL(dccp_rx_hist_new);
+void tfrc_tx_packet_history_exit(void)
+{
+ if (tfrc_tx_hist_slab != NULL) {
+ kmem_cache_destroy(tfrc_tx_hist_slab);
+ tfrc_tx_hist_slab = NULL;
+ }
+}
-void dccp_rx_hist_delete(struct dccp_rx_hist *hist)
+static struct tfrc_tx_hist_entry *
+ tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
{
- const char* name = kmem_cache_name(hist->dccprxh_slab);
+ while (head != NULL && head->seqno != seqno)
+ head = head->next;
- kmem_cache_destroy(hist->dccprxh_slab);
- kfree(name);
- kfree(hist);
+ return head;
}
-EXPORT_SYMBOL_GPL(dccp_rx_hist_delete);
+int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno)
+{
+ struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any());
+
+ if (entry == NULL)
+ return -ENOBUFS;
+ entry->seqno = seqno;
+ entry->stamp = ktime_get_real();
+ entry->next = *headp;
+ *headp = entry;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tfrc_tx_hist_add);
-void dccp_rx_hist_purge(struct dccp_rx_hist *hist, struct list_head *list)
+void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp)
{
- struct dccp_rx_hist_entry *entry, *next;
+ struct tfrc_tx_hist_entry *head = *headp;
+
+ while (head != NULL) {
+ struct tfrc_tx_hist_entry *next = head->next;
- list_for_each_entry_safe(entry, next, list, dccphrx_node) {
- list_del_init(&entry->dccphrx_node);
- kmem_cache_free(hist->dccprxh_slab, entry);
+ kmem_cache_free(tfrc_tx_hist_slab, head);
+ head = next;
}
-}
-EXPORT_SYMBOL_GPL(dccp_rx_hist_purge);
+ *headp = NULL;
+}
+EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge);
-struct dccp_rx_hist_entry *
- dccp_rx_hist_find_data_packet(const struct list_head *list)
+u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
+ const ktime_t now)
{
- struct dccp_rx_hist_entry *entry, *packet = NULL;
+ u32 rtt = 0;
+ struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno);
- list_for_each_entry(entry, list, dccphrx_node)
- if (entry->dccphrx_type == DCCP_PKT_DATA ||
- entry->dccphrx_type == DCCP_PKT_DATAACK) {
- packet = entry;
- break;
- }
+ if (packet != NULL) {
+ rtt = ktime_us_delta(now, packet->stamp);
+ /*
+ * Garbage-collect older (irrelevant) entries:
+ */
+ tfrc_tx_hist_purge(&packet->next);
+ }
- return packet;
+ return rtt;
}
+EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt);
-EXPORT_SYMBOL_GPL(dccp_rx_hist_find_data_packet);
-int dccp_rx_hist_add_packet(struct dccp_rx_hist *hist,
- struct list_head *rx_list,
- struct list_head *li_list,
- struct dccp_rx_hist_entry *packet)
+/*
+ * Receiver History Routines
+ */
+static struct kmem_cache *tfrc_rx_hist_slab;
+
+int __init tfrc_rx_packet_history_init(void)
{
- struct dccp_rx_hist_entry *entry, *next, *iter;
- u8 num_later = 0;
-
- iter = dccp_rx_hist_head(rx_list);
- if (iter == NULL)
- dccp_rx_hist_add_entry(rx_list, packet);
- else {
- const u64 seqno = packet->dccphrx_seqno;
-
- if (after48(seqno, iter->dccphrx_seqno))
- dccp_rx_hist_add_entry(rx_list, packet);
- else {
- if (dccp_rx_hist_entry_data_packet(iter))
- num_later = 1;
-
- list_for_each_entry_continue(iter, rx_list,
- dccphrx_node) {
- if (after48(seqno, iter->dccphrx_seqno)) {
- dccp_rx_hist_add_entry(&iter->dccphrx_node,
- packet);
- goto trim_history;
- }
-
- if (dccp_rx_hist_entry_data_packet(iter))
- num_later++;
-
- if (num_later == TFRC_RECV_NUM_LATE_LOSS) {
- dccp_rx_hist_entry_delete(hist, packet);
- return 1;
- }
- }
+ tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache",
+ sizeof(struct tfrc_rx_hist_entry),
+ 0, SLAB_HWCACHE_ALIGN, NULL);
+ return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0;
+}
- if (num_later < TFRC_RECV_NUM_LATE_LOSS)
- dccp_rx_hist_add_entry(rx_list, packet);
- /*
- * FIXME: else what? should we destroy the packet
- * like above?
- */
- }
+void tfrc_rx_packet_history_exit(void)
+{
+ if (tfrc_rx_hist_slab != NULL) {
+ kmem_cache_destroy(tfrc_rx_hist_slab);
+ tfrc_rx_hist_slab = NULL;
}
+}
-trim_history:
- /*
- * Trim history (remove all packets after the NUM_LATE_LOSS + 1
- * data packets)
- */
- num_later = TFRC_RECV_NUM_LATE_LOSS + 1;
-
- if (!list_empty(li_list)) {
- list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
- if (num_later == 0) {
- list_del_init(&entry->dccphrx_node);
- dccp_rx_hist_entry_delete(hist, entry);
- } else if (dccp_rx_hist_entry_data_packet(entry))
- --num_later;
- }
- } else {
- int step = 0;
- u8 win_count = 0; /* Not needed, but lets shut up gcc */
- int tmp;
- /*
- * We have no loss interval history so we need at least one
- * rtt:s of data packets to approximate rtt.
- */
- list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
- if (num_later == 0) {
- switch (step) {
- case 0:
- step = 1;
- /* OK, find next data packet */
- num_later = 1;
- break;
- case 1:
- step = 2;
- /* OK, find next data packet */
- num_later = 1;
- win_count = entry->dccphrx_ccval;
- break;
- case 2:
- tmp = win_count - entry->dccphrx_ccval;
- if (tmp < 0)
- tmp += TFRC_WIN_COUNT_LIMIT;
- if (tmp > TFRC_WIN_COUNT_PER_RTT + 1) {
- /*
- * We have found a packet older
- * than one rtt remove the rest
- */
- step = 3;
- } else /* OK, find next data packet */
- num_later = 1;
- break;
- case 3:
- list_del_init(&entry->dccphrx_node);
- dccp_rx_hist_entry_delete(hist, entry);
- break;
- }
- } else if (dccp_rx_hist_entry_data_packet(entry))
- --num_later;
- }
- }
+static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry,
+ const struct sk_buff *skb,
+ const u32 ndp)
+{
+ const struct dccp_hdr *dh = dccp_hdr(skb);
+
+ entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+ entry->tfrchrx_ccval = dh->dccph_ccval;
+ entry->tfrchrx_type = dh->dccph_type;
+ entry->tfrchrx_ndp = ndp;
+ entry->tfrchrx_tstamp = ktime_get_real();
+}
+
+void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
+ const struct sk_buff *skb,
+ const u32 ndp)
+{
+ struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h);
+
+ tfrc_rx_hist_entry_from_skb(entry, skb, ndp);
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet);
+
+/* has the packet contained in skb been seen before? */
+int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb)
+{
+ const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq;
+ int i;
+
+ if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0)
+ return 1;
+
+ for (i = 1; i <= h->loss_count; i++)
+ if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq)
+ return 1;
return 0;
}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate);
-EXPORT_SYMBOL_GPL(dccp_rx_hist_add_packet);
+static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b)
+{
+ const u8 idx_a = tfrc_rx_hist_index(h, a),
+ idx_b = tfrc_rx_hist_index(h, b);
+ struct tfrc_rx_hist_entry *tmp = h->ring[idx_a];
+
+ h->ring[idx_a] = h->ring[idx_b];
+ h->ring[idx_b] = tmp;
+}
-u64 dccp_rx_hist_detect_loss(struct list_head *rx_list,
- struct list_head *li_list, u8 *win_loss)
+/*
+ * Private helper functions for loss detection.
+ *
+ * In the descriptions, `Si' refers to the sequence number of entry number i,
+ * whose NDP count is `Ni' (lower case is used for variables).
+ * Note: All __after_loss functions expect that a test against duplicates has
+ * been performed already: the seqno of the skb must not be less than the
+ * seqno of loss_prev; and it must not equal that of any valid hist_entry.
+ */
+static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2)
{
- struct dccp_rx_hist_entry *entry, *next, *packet;
- struct dccp_rx_hist_entry *a_loss = NULL;
- struct dccp_rx_hist_entry *b_loss = NULL;
- u64 seq_loss = DCCP_MAX_SEQNO + 1;
- u8 num_later = TFRC_RECV_NUM_LATE_LOSS;
-
- list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
- if (num_later == 0) {
- b_loss = entry;
- break;
- } else if (dccp_rx_hist_entry_data_packet(entry))
- --num_later;
+ u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
+ s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
+ s2 = DCCP_SKB_CB(skb)->dccpd_seq;
+ int n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp,
+ d12 = dccp_delta_seqno(s1, s2), d2;
+
+ if (d12 > 0) { /* S1 < S2 */
+ h->loss_count = 2;
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2);
+ return;
}
- if (b_loss == NULL)
- goto out;
+ /* S0 < S2 < S1 */
+ d2 = dccp_delta_seqno(s0, s2);
+
+ if (d2 == 1 || n2 >= d2) { /* S2 is direct successor of S0 */
+ int d21 = -d12;
+
+ if (d21 == 1 || n1 >= d21) {
+ /* hole is filled: S0, S2, and S1 are consecutive */
+ h->loss_count = 0;
+ h->loss_start = tfrc_rx_hist_index(h, 1);
+ } else
+ /* gap between S2 and S1: just update loss_prev */
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2);
+
+ } else { /* hole between S0 and S2 */
+ /*
+ * Reorder history to insert S2 between S0 and s1
+ */
+ tfrc_rx_hist_swap(h, 0, 3);
+ h->loss_start = tfrc_rx_hist_index(h, 3);
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2);
+ h->loss_count = 2;
+ }
+}
- num_later = 1;
- list_for_each_entry_safe_continue(entry, next, rx_list, dccphrx_node) {
- if (num_later == 0) {
- a_loss = entry;
- break;
- } else if (dccp_rx_hist_entry_data_packet(entry))
- --num_later;
+/* return 1 if a new loss event has been identified */
+static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3)
+{
+ u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
+ s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
+ s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno,
+ s3 = DCCP_SKB_CB(skb)->dccpd_seq;
+ int n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp,
+ d23 = dccp_delta_seqno(s2, s3), d13, d3, d31;
+
+ if (d23 > 0) { /* S2 < S3 */
+ h->loss_count = 3;
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3);
+ return 1;
}
- if (a_loss == NULL) {
- if (list_empty(li_list)) {
- /* no loss event have occured yet */
- LIMIT_NETDEBUG("%s: TODO: find a lost data packet by "
- "comparing to initial seqno\n",
- __FUNCTION__);
- goto out;
- } else {
- LIMIT_NETDEBUG("%s: Less than 4 data pkts in history!",
- __FUNCTION__);
- goto out;
- }
+ /* S3 < S2 */
+ d13 = dccp_delta_seqno(s1, s3);
+
+ if (d13 > 0) {
+ /*
+ * The sequence number order is S1, S3, S2
+ * Reorder history to insert entry between S1 and S2
+ */
+ tfrc_rx_hist_swap(h, 2, 3);
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3);
+ h->loss_count = 3;
+ return 1;
}
- /* Locate a lost data packet */
- entry = packet = b_loss;
- list_for_each_entry_safe_continue(entry, next, rx_list, dccphrx_node) {
- u64 delta = dccp_delta_seqno(entry->dccphrx_seqno,
- packet->dccphrx_seqno);
-
- if (delta != 0) {
- if (dccp_rx_hist_entry_data_packet(packet))
- --delta;
- /*
- * FIXME: check this, probably this % usage is because
- * in earlier drafts the ndp count was just 8 bits
- * long, but now it cam be up to 24 bits long.
- */
-#if 0
- if (delta % DCCP_NDP_LIMIT !=
- (packet->dccphrx_ndp -
- entry->dccphrx_ndp) % DCCP_NDP_LIMIT)
-#endif
- if (delta != packet->dccphrx_ndp - entry->dccphrx_ndp) {
- seq_loss = entry->dccphrx_seqno;
- dccp_inc_seqno(&seq_loss);
+ /* S0 < S3 < S1 */
+ d31 = -d13;
+ d3 = dccp_delta_seqno(s0, s3);
+
+ if (d3 == 1 || n3 >= d3) { /* S3 is a successor of S0 */
+
+ if (d31 == 1 || n1 >= d31) {
+ /* hole between S0 and S1 filled by S3 */
+ int d2 = dccp_delta_seqno(s1, s2),
+ n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp;
+
+ if (d2 == 1 || n2 >= d2) {
+ /* entire hole filled by S0, S3, S1, S2 */
+ h->loss_start = tfrc_rx_hist_index(h, 2);
+ h->loss_count = 0;
+ } else {
+ /* gap remains between S1 and S2 */
+ h->loss_start = tfrc_rx_hist_index(h, 1);
+ h->loss_count = 1;
}
- }
- packet = entry;
- if (packet == a_loss)
- break;
- }
-out:
- if (seq_loss != DCCP_MAX_SEQNO + 1)
- *win_loss = a_loss->dccphrx_ccval;
- else
- *win_loss = 0; /* Paranoia */
- return seq_loss;
-}
+ } else /* gap exists between S3 and S1, loss_count stays at 2 */
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3);
-EXPORT_SYMBOL_GPL(dccp_rx_hist_detect_loss);
+ return 0;
+ }
-struct dccp_tx_hist *dccp_tx_hist_new(const char *name)
-{
- struct dccp_tx_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
- static const char dccp_tx_hist_mask[] = "tx_hist_%s";
- char *slab_name;
-
- if (hist == NULL)
- goto out;
-
- slab_name = kmalloc(strlen(name) + sizeof(dccp_tx_hist_mask) - 1,
- GFP_ATOMIC);
- if (slab_name == NULL)
- goto out_free_hist;
-
- sprintf(slab_name, dccp_tx_hist_mask, name);
- hist->dccptxh_slab = kmem_cache_create(slab_name,
- sizeof(struct dccp_tx_hist_entry),
- 0, SLAB_HWCACHE_ALIGN,
- NULL, NULL);
- if (hist->dccptxh_slab == NULL)
- goto out_free_slab_name;
-out:
- return hist;
-out_free_slab_name:
- kfree(slab_name);
-out_free_hist:
- kfree(hist);
- hist = NULL;
- goto out;
-}
+ /*
+ * The remaining case: S3 is not a successor of S0.
+ * Sequence order is S0, S3, S1, S2; reorder to insert between S0 and S1
+ */
+ tfrc_rx_hist_swap(h, 0, 3);
+ h->loss_start = tfrc_rx_hist_index(h, 3);
+ tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3);
+ h->loss_count = 3;
-EXPORT_SYMBOL_GPL(dccp_tx_hist_new);
+ return 1;
+}
-void dccp_tx_hist_delete(struct dccp_tx_hist *hist)
+/* return the signed modulo-2^48 sequence number distance from entry e1 to e2 */
+static s64 tfrc_rx_hist_delta_seqno(struct tfrc_rx_hist *h, u8 e1, u8 e2)
{
- const char* name = kmem_cache_name(hist->dccptxh_slab);
+ DCCP_BUG_ON(e1 > h->loss_count || e2 > h->loss_count);
- kmem_cache_destroy(hist->dccptxh_slab);
- kfree(name);
- kfree(hist);
+ return dccp_delta_seqno(tfrc_rx_hist_entry(h, e1)->tfrchrx_seqno,
+ tfrc_rx_hist_entry(h, e2)->tfrchrx_seqno);
}
-EXPORT_SYMBOL_GPL(dccp_tx_hist_delete);
-
-struct dccp_tx_hist_entry *
- dccp_tx_hist_find_entry(const struct list_head *list, const u64 seq)
+/* recycle RX history records to continue loss detection if necessary */
+static void __three_after_loss(struct tfrc_rx_hist *h)
{
- struct dccp_tx_hist_entry *packet = NULL, *entry;
+ /*
+ * The distance between S0 and S1 is always greater than 1 and the NDP
+ * count of S1 is smaller than this distance. Otherwise there would
+ * have been no loss. Hence it is only necessary to see whether there
+ * are further missing data packets between S1/S2 and S2/S3.
+ */
+ int d2 = tfrc_rx_hist_delta_seqno(h, 1, 2),
+ d3 = tfrc_rx_hist_delta_seqno(h, 2, 3),
+ n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp,
+ n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp;
+
+ if (d2 == 1 || n2 >= d2) { /* S2 is successor to S1 */
- list_for_each_entry(entry, list, dccphtx_node)
- if (entry->dccphtx_seqno == seq) {
- packet = entry;
- break;
+ if (d3 == 1 || n3 >= d3) {
+ /* S3 is successor of S2: entire hole is filled */
+ h->loss_start = tfrc_rx_hist_index(h, 3);
+ h->loss_count = 0;
+ } else {
+ /* gap between S2 and S3 */
+ h->loss_start = tfrc_rx_hist_index(h, 2);
+ h->loss_count = 1;
}
- return packet;
+ } else { /* gap between S1 and S2 */
+ h->loss_start = tfrc_rx_hist_index(h, 1);
+ h->loss_count = 2;
+ }
}
-EXPORT_SYMBOL_GPL(dccp_tx_hist_find_entry);
+/**
+ * tfrc_rx_handle_loss - Loss detection and further processing
+ * @h: The non-empty RX history object
+ * @lh: Loss Intervals database to update
+ * @skb: Currently received packet
+ * @ndp: The NDP count belonging to @skb
+ * @calc_first_li: Caller-dependent computation of first loss interval in @lh
+ * @sk: Used by @calc_first_li (see tfrc_lh_interval_add)
+ * Chooses action according to pending loss, updates LI database when a new
+ * loss was detected, and does required post-processing. Returns 1 when caller
+ * should send feedback, 0 otherwise.
+ */
+int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
+ struct tfrc_loss_hist *lh,
+ struct sk_buff *skb, u32 ndp,
+ u32 (*calc_first_li)(struct sock *), struct sock *sk)
+{
+ int is_new_loss = 0;
+
+ if (h->loss_count == 1) {
+ __one_after_loss(h, skb, ndp);
+ } else if (h->loss_count != 2) {
+ DCCP_BUG("invalid loss_count %d", h->loss_count);
+ } else if (__two_after_loss(h, skb, ndp)) {
+ /*
+ * Update Loss Interval database and recycle RX records
+ */
+ is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk);
+ __three_after_loss(h);
+ }
+ return is_new_loss;
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss);
-void dccp_tx_hist_purge_older(struct dccp_tx_hist *hist,
- struct list_head *list,
- struct dccp_tx_hist_entry *packet)
+int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h)
{
- struct dccp_tx_hist_entry *next;
+ int i;
+
+ for (i = 0; i <= TFRC_NDUPACK; i++) {
+ h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC);
+ if (h->ring[i] == NULL)
+ goto out_free;
+ }
- list_for_each_entry_safe_continue(packet, next, list, dccphtx_node) {
- list_del_init(&packet->dccphtx_node);
- dccp_tx_hist_entry_delete(hist, packet);
+ h->loss_count = h->loss_start = 0;
+ return 0;
+
+out_free:
+ while (i-- != 0) {
+ kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
+ h->ring[i] = NULL;
}
+ return -ENOBUFS;
}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_alloc);
-EXPORT_SYMBOL_GPL(dccp_tx_hist_purge_older);
+void tfrc_rx_hist_purge(struct tfrc_rx_hist *h)
+{
+ int i;
-void dccp_tx_hist_purge(struct dccp_tx_hist *hist, struct list_head *list)
+ for (i = 0; i <= TFRC_NDUPACK; ++i)
+ if (h->ring[i] != NULL) {
+ kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
+ h->ring[i] = NULL;
+ }
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge);
+
+/**
+ * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
+ */
+static inline struct tfrc_rx_hist_entry *
+ tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h)
{
- struct dccp_tx_hist_entry *entry, *next;
+ return h->ring[0];
+}
- list_for_each_entry_safe(entry, next, list, dccphtx_node) {
- list_del_init(&entry->dccphtx_node);
- dccp_tx_hist_entry_delete(hist, entry);
- }
+/**
+ * tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry
+ */
+static inline struct tfrc_rx_hist_entry *
+ tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h)
+{
+ return h->ring[h->rtt_sample_prev];
}
-EXPORT_SYMBOL_GPL(dccp_tx_hist_purge);
+/**
+ * tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal
+ * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able
+ * to compute a sample with given data - calling function should check this.
+ */
+u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb)
+{
+ u32 sample = 0,
+ delta_v = SUB16(dccp_hdr(skb)->dccph_ccval,
+ tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
+
+ if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */
+ if (h->rtt_sample_prev == 2) { /* previous candidate stored */
+ sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
+ tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
+ if (sample)
+ sample = 4 / sample *
+ ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp,
+ tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp);
+ else /*
+ * FIXME: This condition is in principle not
+ * possible but occurs when CCID is used for
+ * two-way data traffic. I have tried to trace
+ * it, but the cause does not seem to be here.
+ */
+ DCCP_BUG("please report to dccp@vger.kernel.org"
+ " => prev = %u, last = %u",
+ tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
+ tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
+ } else if (delta_v < 1) {
+ h->rtt_sample_prev = 1;
+ goto keep_ref_for_next_time;
+ }
-MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
- "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
-MODULE_DESCRIPTION("DCCP TFRC library");
-MODULE_LICENSE("GPL");
+ } else if (delta_v == 4) /* optimal match */
+ sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp));
+ else { /* suboptimal match */
+ h->rtt_sample_prev = 2;
+ goto keep_ref_for_next_time;
+ }
+
+ if (unlikely(sample > DCCP_SANE_RTT_MAX)) {
+ DCCP_WARN("RTT sample %u too large, using max\n", sample);
+ sample = DCCP_SANE_RTT_MAX;
+ }
+
+ h->rtt_sample_prev = 0; /* use current entry as next reference */
+keep_ref_for_next_time:
+
+ return sample;
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt);