5 files changed, 84 insertions, 33 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 8266dfde89c1..8f112d18d450 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -1,6 +1,7 @@
 /*
  *  net/dccp/ccids/ccid3.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>
  *
@@ -33,11 +34,7 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
-#include "../ccid.h"
 #include "../dccp.h"
-#include "lib/packet_history.h"
-#include "lib/loss_interval.h"
-#include "lib/tfrc.h"
 #include "ccid3.h"
 
 #include <asm/unaligned.h>
@@ -757,6 +754,46 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
         return 0;
 }
 
+/** ccid3_first_li  -  Implements [RFC 3448, 6.3.1]
+ *
+ * Determine the length of the first loss interval via inverse lookup.
+ * Assume that X_recv can be computed by the throughput equation
+ *                  s
+ *      X_recv = --------
+ *               R * fval
+ * Find some p such that f(p) = fval; return 1/p (scaled).
+ */
+static u32 ccid3_first_li(struct sock *sk)
+{
+        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+        u32 x_recv, p, delta;
+        u64 fval;
+
+        if (hcrx->ccid3hcrx_rtt == 0) {
+                DCCP_WARN("No RTT estimate available, using fallback RTT\n");
+                hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
+        }
+
+        delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback));
+        x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
+        if (x_recv == 0) {              /* would also trigger divide-by-zero */
+                DCCP_WARN("X_recv==0\n");
+                if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
+                        DCCP_BUG("stored value of X_recv is zero");
+                        return ~0U;
+                }
+        }
+
+        fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt);
+        fval = scaled_div32(fval, x_recv);
+        p = tfrc_calc_x_reverse_lookup(fval);
+
+        ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
+                       "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
+
+        return p == 0 ? ~0U : scaled_div(1, p);
+}
+
 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
 {
         struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
@@ -794,6 +831,14 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         /*
          * Handle pending losses and otherwise check for new loss
          */
+        if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist) &&
+            tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist,
+                                &hcrx->ccid3hcrx_li_hist,
+                                skb, ndp, ccid3_first_li, sk) ) {
+                do_feedback = CCID3_FBACK_PARAM_CHANGE;
+                goto done_receiving;
+        }
+
         if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
                 goto update_records;
 
@@ -803,7 +848,7 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         if (unlikely(!is_data_packet))
                 goto update_records;
 
-        if (list_empty(&hcrx->ccid3hcrx_li_hist)) {  /* no loss so far: p = 0 */
+        if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) {
                 const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
                 /*
                  * Empty loss history: no loss so far, hence p stays 0.
@@ -812,6 +857,13 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                  */
                 if (sample != 0)
                         hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
+
+        } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) {
+                /*
+                 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
+                 * has decreased (resp. p has increased), send feedback now.
+                 */
+                do_feedback = CCID3_FBACK_PARAM_CHANGE;
         }
 
         /*
@@ -823,6 +875,7 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
 update_records:
         tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
 
+done_receiving:
         if (do_feedback)
                 ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
 }
@@ -831,10 +884,8 @@ static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
 {
         struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
 
-        ccid3_pr_debug("entry\n");
-
         hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
-        INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
+        tfrc_lh_init(&hcrx->ccid3hcrx_li_hist);
         return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
 }
 
@@ -844,11 +895,8 @@ static void ccid3_hc_rx_exit(struct sock *sk)
 
         ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
 
-        /* Empty packet history */
         tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist);
-
-        /* Empty loss interval history */
-        dccp_li_hist_purge(&hcrx->ccid3hcrx_li_hist);
+        tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist);
 }
 
 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h
index 6ceeb8013f58..e9f6ff4f0552 100644
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -41,7 +41,7 @@
 #include <linux/list.h>
 #include <linux/types.h>
 #include <linux/tfrc.h>
-#include "lib/packet_history.h"
+#include "lib/tfrc.h"
 #include "../ccid.h"
 
 /* Two seconds as per RFC 3448 4.2 */
@@ -141,8 +141,8 @@ enum ccid3_hc_rx_states {
  *  @ccid3hcrx_bytes_recv  -  Total sum of DCCP payload bytes
  *  @ccid3hcrx_tstamp_last_feedback  -  Time at which last feedback was sent
  *  @ccid3hcrx_tstamp_last_ack  -  Time at which last feedback was sent
- *  @ccid3hcrx_hist  -  Packet history
- *  @ccid3hcrx_li_hist  -  Loss Interval History
+ *  @ccid3hcrx_hist  -  Packet history (loss detection + RTT sampling)
+ *  @ccid3hcrx_li_hist  -  Loss Interval database
  *  @ccid3hcrx_s  -  Received packet size in bytes
  *  @ccid3hcrx_pinv  -  Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
  */
@@ -156,9 +156,9 @@ struct ccid3_hc_rx_sock {
         u32                             ccid3hcrx_bytes_recv;
         ktime_t                         ccid3hcrx_tstamp_last_feedback;
         struct tfrc_rx_hist             ccid3hcrx_hist;
-        struct list_head                ccid3hcrx_li_hist;
+        struct tfrc_loss_hist           ccid3hcrx_li_hist;
         u16                             ccid3hcrx_s;
-        u32                             ccid3hcrx_pinv;
+#define ccid3hcrx_pinv                  ccid3hcrx_li_hist.i_mean
 };
 
 static inline struct ccid3_hc_rx_sock *ccid3_hc_rx_sk(const struct sock *sk)
diff --git a/net/dccp/ccids/lib/loss_interval.c b/net/dccp/ccids/lib/loss_interval.c
index 39980d1f5352..8b962c1f14b8 100644
--- a/net/dccp/ccids/lib/loss_interval.c
+++ b/net/dccp/ccids/lib/loss_interval.c
@@ -435,18 +435,18 @@ int tfrc_lh_interval_add(struct tfrc_loss_hist *lh, struct tfrc_rx_hist *rh,
 }
 EXPORT_SYMBOL_GPL(tfrc_lh_interval_add);
 
-int __init dccp_li_init(void)
+int __init tfrc_li_init(void)
 {
-        dccp_li_cachep = kmem_cache_create("dccp_li_hist",
-                                           sizeof(struct dccp_li_hist_entry),
-                                           0, SLAB_HWCACHE_ALIGN, NULL);
-        return dccp_li_cachep == NULL ? -ENOBUFS : 0;
+        tfrc_lh_slab = kmem_cache_create("tfrc_li_hist",
+                                         sizeof(struct tfrc_loss_interval), 0,
+                                         SLAB_HWCACHE_ALIGN, NULL);
+        return tfrc_lh_slab == NULL ? -ENOBUFS : 0;
 }
 
-void dccp_li_exit(void)
+void tfrc_li_exit(void)
 {
-        if (dccp_li_cachep != NULL) {
-                kmem_cache_destroy(dccp_li_cachep);
-                dccp_li_cachep = NULL;
+        if (tfrc_lh_slab != NULL) {
+                kmem_cache_destroy(tfrc_lh_slab);
+                tfrc_lh_slab = NULL;
         }
 }
diff --git a/net/dccp/ccids/lib/tfrc.c b/net/dccp/ccids/lib/tfrc.c
index 20763fa75d44..d1dfbb8de64c 100644
--- a/net/dccp/ccids/lib/tfrc.c
+++ b/net/dccp/ccids/lib/tfrc.c
@@ -19,12 +19,12 @@ extern void tfrc_tx_packet_history_exit(void);
 extern int  tfrc_rx_packet_history_init(void);
 extern void tfrc_rx_packet_history_exit(void);
 
-extern int  dccp_li_init(void);
-extern void dccp_li_exit(void);
+extern int  tfrc_li_init(void);
+extern void tfrc_li_exit(void);
 
 static int __init tfrc_module_init(void)
 {
-        int rc = dccp_li_init();
+        int rc = tfrc_li_init();
 
         if (rc)
                 goto out;
@@ -41,7 +41,7 @@ static int __init tfrc_module_init(void)
 out_free_tx_history:
         tfrc_tx_packet_history_exit();
 out_free_loss_intervals:
-        dccp_li_exit();
+        tfrc_li_exit();
 out:
         return rc;
 }
@@ -50,7 +50,7 @@ static void __exit tfrc_module_exit(void)
 {
         tfrc_rx_packet_history_exit();
         tfrc_tx_packet_history_exit();
-        dccp_li_exit();
+        tfrc_li_exit();
 }
 
 module_init(tfrc_module_init);
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index f4a5ea116e34..07dcbe73b50c 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -74,9 +74,12 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo);
 
 #define DCCP_RTO_MAX ((unsigned)(120 * HZ)) /* FIXME: using TCP value */
 
-/* bounds for sampled RTT values from packet exchanges (in usec) */
+/*
+ * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4
+ */
 #define DCCP_SANE_RTT_MIN       100
-#define DCCP_SANE_RTT_MAX       (4 * USEC_PER_SEC)
+#define DCCP_FALLBACK_RTT       (USEC_PER_SEC / 5)
+#define DCCP_SANE_RTT_MAX       (3 * USEC_PER_SEC)
 
 /* Maximal interval between probes for local resources.  */
 #define DCCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ / 2U))