From 45cae1d1aba068fe4a9f3a3dc424fee6b51dc47d Mon Sep 17 00:00:00 2001
From: Ismael Gomez <ismagom@gmail.com>
Date: Wed, 21 Mar 2018 13:10:13 +0100
Subject: [PATCH] Fix srsENB DL TCP stalling

---
 srsenb/src/mac/scheduler.cc        | 27 +++++++++++++++++----------
 srsenb/src/mac/scheduler_metric.cc |  4 +---
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/srsenb/src/mac/scheduler.cc b/srsenb/src/mac/scheduler.cc
index 51f161d4a..995363045 100644
--- a/srsenb/src/mac/scheduler.cc
+++ b/srsenb/src/mac/scheduler.cc
@@ -254,18 +254,22 @@ uint32_t sched::get_ul_buffer(uint16_t rnti)
   return ret; 
 }
 
+/* \Warning: This function is not mutexed because it can produce late changes on the buffer state while
+ * the scheduler is already allocating data, resulting in empty grants.
+ * Ideally we would like the scheduler to query the RLC for buffer states in order to get the most updated
+ * buffer state with the minimum overhead. However, the current architecture is designed to be compliant
+ * with the FAPI interface
+ */
 int sched::dl_rlc_buffer_state(uint16_t rnti, uint32_t lc_id, uint32_t tx_queue, uint32_t retx_queue)
 {
-  pthread_mutex_lock(&mutex);
-  int ret = 0; 
-  if (ue_db.count(rnti)) {         
+  int ret = 0;
+  if (ue_db.count(rnti)) {
     ue_db[rnti].dl_buffer_state(lc_id, tx_queue, retx_queue);
   } else {
     Error("User rnti=0x%x not found\n", rnti);
     ret = -1;
   }
-  pthread_mutex_unlock(&mutex);
-  return ret; 
+  return ret;
 }
 
 int sched::dl_mac_buffer_state(uint16_t rnti, uint32_t ce_code)
@@ -676,10 +680,11 @@ int sched::dl_sched_data(dl_sched_data_t data[MAX_DATA_LIST])
   
   int nof_data_elems = 0; 
   for(std::map<uint16_t, sched_ue>::iterator iter=ue_db.begin(); iter!=ue_db.end(); ++iter) {
-    sched_ue *user      = (sched_ue*) &iter->second;
-    uint16_t rnti = (uint16_t) iter->first; 
+    sched_ue *user = (sched_ue*) &iter->second;
+    uint16_t rnti  = (uint16_t) iter->first;
 
-    dl_harq_proc *h = dl_metric->get_user_allocation(user); 
+    uint32_t data_before = user->get_pending_dl_new_data(current_tti);
+    dl_harq_proc *h = dl_metric->get_user_allocation(user);
     srslte_dci_format_t dci_format = user->get_dci_format();
     data[nof_data_elems].dci_format = dci_format;
 
@@ -706,10 +711,12 @@ int sched::dl_sched_data(dl_sched_data_t data[MAX_DATA_LIST])
             Error("DCI format (%d) not implemented\n", dci_format);
         }
         if (tbs > 0) {
-          log_h->info("SCHED: DL %s rnti=0x%x, pid=%d, mask=0x%x, dci=%d,%d, n_rtx=%d, tbs=%d, buffer=%d, tb_en={%s,%s}\n",
+          log_h->info("SCHED: DL %s rnti=0x%x, pid=%d, mask=0x%x, dci=%d,%d, n_rtx=%d, tbs=%d, buffer=%d/%d, tb_en={%s,%s}\n",
                       !is_newtx?"retx":"tx", rnti, h->get_id(), h->get_rbgmask(), 
                       data[nof_data_elems].dci_location.L, data[nof_data_elems].dci_location.ncce, h->nof_retx(0) + h->nof_retx(1),
-                      tbs, user->get_pending_dl_new_data(current_tti), data[nof_data_elems].dci.tb_en[0]?"y":"n",
+                      tbs,
+                      data_before, user->get_pending_dl_new_data(current_tti),
+                      data[nof_data_elems].dci.tb_en[0]?"y":"n",
                       data[nof_data_elems].dci.tb_en[1]?"y":"n");
           nof_data_elems++;
         } else {
diff --git a/srsenb/src/mac/scheduler_metric.cc b/srsenb/src/mac/scheduler_metric.cc
index f6fb9d9df..1d9cdb954 100644
--- a/srsenb/src/mac/scheduler_metric.cc
+++ b/srsenb/src/mac/scheduler_metric.cc
@@ -148,9 +148,7 @@ dl_harq_proc* dl_metric_rr::get_user_allocation(sched_ue *user)
   if (pending_data || (h && !h->is_empty())) {
 #endif
     if (nof_users_with_data) {
-      if (nof_users_with_data == 2) {
-      }
-      if ((current_tti%nof_users_with_data) != user->ue_idx) {      
+      if ((current_tti%nof_users_with_data) != user->ue_idx) {
         return NULL; 
       }    
     }