hotfix: remove HARQ process ID freelist

It creates more problems than it solves.

We replace this approach by a straightforward
synchronous one.

Now in the downlink, at frame f and subframe s
we use HARQ process (f * 10 + s) % 8.
This is similar to uplink scheduling.

openair1/PHY/LTE_TRANSPORT/dci_tools.c

@@ -1126,12 +1126,8 @@ int generate_eNB_dlsch_params_from_dci(int frame,
 
     dlsch[0]->harq_ids[subframe] = harq_pid;
 
-    if (dlsch0_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch[0], harq_pid);
+    if (dlsch0_harq->round == 0)
       dlsch0_harq->status = ACTIVE;
-    }
 
     break;
 
@@ -1265,9 +1261,6 @@ int generate_eNB_dlsch_params_from_dci(int frame,
 
 
     if (dlsch0_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch[0], harq_pid);
       dlsch0_harq->status = ACTIVE;
       //            printf("Setting DLSCH process %d to ACTIVE\n",harq_pid);
       // MCS and TBS don't change across HARQ rounds
@@ -1635,19 +1628,11 @@ int generate_eNB_dlsch_params_from_dci(int frame,
     }
 
     // reset HARQ process if this is the first transmission
-    if (dlsch0_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch0, harq_pid);
+    if (dlsch0_harq->round == 0)
       dlsch0_harq->status = ACTIVE;
-    }
 
-    if (dlsch1_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch1_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch1, harq_pid);
+    if (dlsch1_harq->round == 0)
       dlsch1_harq->status = ACTIVE;
-    }
 
     dlsch0->rnti = rnti;
     dlsch1->rnti = rnti;
@@ -2022,19 +2007,11 @@ int generate_eNB_dlsch_params_from_dci(int frame,
     }
 
     // reset HARQ process if this is the first transmission
-    if ((dlsch0->active==1) && (dlsch0_harq->round == 0)) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch0, harq_pid);
+    if ((dlsch0->active==1) && (dlsch0_harq->round == 0))
       dlsch0_harq->status = ACTIVE;
-    }
 
-    if ((dlsch1->active==1) && (dlsch1_harq->round == 0)) {
-      /* necessary test? */
-      if (dlsch1_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch1, harq_pid);
+    if ((dlsch1->active==1) && (dlsch1_harq->round == 0))
       dlsch1_harq->status = ACTIVE;
-    }
 
     dlsch0->rnti = rnti;
     dlsch1->rnti = rnti;
@@ -2174,23 +2151,16 @@ int generate_eNB_dlsch_params_from_dci(int frame,
     // check if either TB is disabled (see 36-213 V8.6 p. 26)
 
 
-    if ((dlsch0_harq->rvidx == 1) && (dlsch0_harq->mcs == 0)) {
-      LOG_W(PHY, "what to do with respect to remove_harq_pid_from_freelist?\n");
+    if ((dlsch0_harq->rvidx == 1) && (dlsch0_harq->mcs == 0))
       dlsch0_harq->status = DISABLED;
-    }
 
-    if ((dlsch1_harq->rvidx == 1) && (dlsch1_harq->mcs == 0)) {
-      LOG_W(PHY, "what to do with respect to remove_harq_pid_from_freelist?\n");
+    if ((dlsch1_harq->rvidx == 1) && (dlsch1_harq->mcs == 0))
       dlsch1_harq->status = DISABLED;
-    }
 
     dlsch0_harq->Nl        = 1;
 
 
     if (dlsch0_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch0, harq_pid);
       dlsch0_harq->status = ACTIVE;
       //      printf("Setting DLSCH process %d to ACTIVE\n",harq_pid);
     }
@@ -2355,17 +2325,11 @@ int generate_eNB_dlsch_params_from_dci(int frame,
 
 
     if ((dlsch0_harq->round == 0) && (dlsch0->active == 1) ) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch0, harq_pid);
       dlsch0_harq->status      = ACTIVE;
       dlsch0_harq->mcs         = mcs1;
     }
 
     if ((dlsch1_harq->round == 0) && (dlsch1->active == 1) ) {
-      /* necessary test? */
-      if (dlsch1_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch1, harq_pid);
       dlsch1_harq->status      = ACTIVE;
       dlsch1_harq->mcs         = mcs2;
     }
@@ -2529,9 +2493,6 @@ int generate_eNB_dlsch_params_from_dci(int frame,
 
 
     if (dlsch0_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch0, harq_pid);
       dlsch0_harq->status = ACTIVE;
       //      printf("Setting DLSCH process %d to ACTIVE\n",harq_pid);
     }
@@ -2661,9 +2622,6 @@ int generate_eNB_dlsch_params_from_dci(int frame,
 
     //    dlsch0_harq->Ndi         = ((DCI1E_5MHz_2A_M10PRB_TDD_t *)dci_pdu)->ndi;
     if (dlsch0_harq->round == 0) {
-      /* necessary test? */
-      if (dlsch0_harq->status == SCH_IDLE)
-        remove_harq_pid_from_freelist(dlsch0, harq_pid);
       dlsch0_harq->status = ACTIVE;
       //      printf("Setting DLSCH process %d to ACTIVE\n",harq_pid);
     }

openair1/PHY/LTE_TRANSPORT/defs.h

@@ -258,13 +258,6 @@ typedef struct {
   uint8_t error_threshold;
   /// Pointers to 8 HARQ processes for the DLSCH
   LTE_DL_eNB_HARQ_t *harq_processes[8];
-  /// circular list of free harq PIDs (the oldest come first)
-  /// (10 is arbitrary value, must be > to max number of DL HARQ processes in LTE)
-  int harq_pid_freelist[10];
-  /// the head position of the free list (if list is free then head=tail)
-  int head_freelist;
-  /// the tail position of the free list
-  int tail_freelist;
   /// Number of soft channel bits
   uint32_t G;
   /// Codebook index for this dlsch (0,1,2,3)

openair1/PHY/LTE_TRANSPORT/dlsch_coding.c

@@ -156,9 +156,6 @@ LTE_eNB_DLSCH_t *new_eNB_dlsch(unsigned char Kmimo,unsigned char Mdlharq,uint32_
     for (i=0; i<10; i++)
       dlsch->harq_ids[i] = Mdlharq;
 
-    dlsch->head_freelist = 0;
-    dlsch->tail_freelist = 0;
-
     for (i=0; i<Mdlharq; i++) {
       dlsch->harq_processes[i] = (LTE_DL_eNB_HARQ_t *)malloc16(sizeof(LTE_DL_eNB_HARQ_t));
       LOG_T(PHY, "Required mem size %d (bw scaling %d), dlsch->harq_processes[%d] %p\n",
@@ -199,8 +196,6 @@ LTE_eNB_DLSCH_t *new_eNB_dlsch(unsigned char Kmimo,unsigned char Mdlharq,uint32_
         msg("Can't get harq_p %d\n",i);
         exit_flag=3;
       }
-
-      put_harq_pid_in_freelist(dlsch, i);
     }
 
     if (exit_flag==0) {

openair1/SCHED/defs.h

@@ -400,9 +400,6 @@ uint32_t pdcch_alloc2ul_frame(LTE_DL_FRAME_PARMS *frame_parms,uint32_t frame, ui
 uint16_t get_Np(uint8_t N_RB_DL,uint8_t nCCE,uint8_t plus1);
 
 
-void put_harq_pid_in_freelist(LTE_eNB_DLSCH_t *DLSCH_ptr, int harq_pid);
-void remove_harq_pid_from_freelist(LTE_eNB_DLSCH_t *DLSCH_ptr, int harq_pid);
-
 int8_t find_ue(uint16_t rnti, PHY_VARS_eNB *phy_vars_eNB);
 int32_t add_ue(int16_t rnti, PHY_VARS_eNB *phy_vars_eNB);
 int mac_phy_remove_ue(module_id_t Mod_idP,rnti_t rnti);

openair1/SCHED/phy_procedures_lte_eNb.c

@@ -133,30 +133,6 @@ uint8_t is_SR_subframe(PHY_VARS_eNB *phy_vars_eNB,uint8_t UE_id,uint8_t sched_su
   return(0);
 }
 
-void put_harq_pid_in_freelist(LTE_eNB_DLSCH_t *DLSCH_ptr, int harq_pid)
-{
-  DLSCH_ptr->harq_pid_freelist[DLSCH_ptr->tail_freelist] = harq_pid;
-  DLSCH_ptr->tail_freelist = (DLSCH_ptr->tail_freelist + 1) % 10;
-}
-
-void remove_harq_pid_from_freelist(LTE_eNB_DLSCH_t *DLSCH_ptr, int harq_pid)
-{
-  if (DLSCH_ptr->head_freelist == DLSCH_ptr->tail_freelist) {
-    LOG_E(PHY, "%s:%d: you cannot read this!\n", __FILE__, __LINE__);
-    abort();
-  }
-  /* basic check, in case several threads deal with the free list at the same time
-   * in normal situations it should not happen, that's also why we don't use any
-   * locking mechanism to protect the free list
-   * to be refined in case things don't work properly
-   */
-  if (harq_pid != DLSCH_ptr->harq_pid_freelist[DLSCH_ptr->head_freelist]) {
-    LOG_E(PHY, "%s:%d: critical error, get in touch with the authors\n", __FILE__, __LINE__);
-    abort();
-  }
-  DLSCH_ptr->head_freelist = (DLSCH_ptr->head_freelist + 1) % 10;
-}
-
 int32_t add_ue(int16_t rnti, PHY_VARS_eNB *phy_vars_eNB)
 {
   uint8_t i;
@@ -221,12 +197,6 @@ int mac_phy_remove_ue(module_id_t Mod_idP,rnti_t rntiP) {
 	  memset(&phy_vars_eNB->eNB_UE_stats[i],0,sizeof(LTE_eNB_UE_stats));
 	  //  mac_exit_wrapper("Removing UE");
 	  
-	  /* clear the harq pid freelist */
-	  phy_vars_eNB->dlsch_eNB[i][0]->head_freelist = 0;
-	  phy_vars_eNB->dlsch_eNB[i][0]->tail_freelist = 0;
-	  for (j = 0; j < 8; j++)
-	    put_harq_pid_in_freelist(phy_vars_eNB->dlsch_eNB[i][0], j);
-	  
 	  return(i);
 	}
       }
@@ -258,9 +228,8 @@ int get_ue_active_harq_pid(const uint8_t Mod_id,const uint8_t CC_id,const uint16
   LTE_eNB_DLSCH_t *DLSCH_ptr;
   LTE_eNB_ULSCH_t *ULSCH_ptr;
   uint8_t ulsch_subframe,ulsch_frame;
-  uint8_t i;
+  int i;
   int8_t UE_id = find_ue(rnti,PHY_vars_eNB_g[Mod_id][CC_id]);
-  int sf1=(10*frame)+subframe,sf2,sfdiff,sfdiff_max=7;
 
   if (UE_id==-1) {
     LOG_D(PHY,"Cannot find UE with rnti %x (Mod_id %d, CC_id %d)\n",rnti, Mod_id, CC_id);
@@ -271,40 +240,19 @@ int get_ue_active_harq_pid(const uint8_t Mod_id,const uint8_t CC_id,const uint16
   if (ul_flag == 0)  {// this is a DL request
     DLSCH_ptr = PHY_vars_eNB_g[Mod_id][CC_id]->dlsch_eNB[(uint32_t)UE_id][0];
 
-    // set to no available process first
-    *harq_pid = -1;
-
-    for (i=0; i<DLSCH_ptr->Mdlharq; i++) {
-      if (DLSCH_ptr->harq_processes[i]!=NULL) {
-	if (DLSCH_ptr->harq_processes[i]->status == ACTIVE) {
-	  sf2 = (DLSCH_ptr->harq_processes[i]->frame*10) + DLSCH_ptr->harq_processes[i]->subframe;
-	  if (sf2<=sf1)
-	    sfdiff = sf1-sf2;
-	  else // this happens when wrapping around 1024 frame barrier
-	    sfdiff = 10240 + sf1-sf2;
-	  LOG_D(PHY,"process %d is active, round %d (waiting %d)\n",i,DLSCH_ptr->harq_processes[i]->round,sfdiff);
-
-	  if (sfdiff>sfdiff_max) { // this is an active process that is waiting longer than the others (and longer than 7 ms)
-	    sfdiff_max = sfdiff; 
-	    *harq_pid = i;
-	    *round = DLSCH_ptr->harq_processes[i]->round;
-	  }
-	}
-      } else { // a process is not defined
-	LOG_E(PHY,"[eNB %d] DLSCH process %d for rnti %x (UE_id %d) not allocated\n",Mod_id,i,rnti,UE_id);
-	return(-1);
-      }
-    }
+    /* let's go synchronous for the moment - maybe we can change at some point */
+    i = (frame * 10 + subframe) % 8;
 
-    /* if no active harq pid, get the oldest in the freelist, if any */
-    if (*harq_pid == 255 && DLSCH_ptr->head_freelist != DLSCH_ptr->tail_freelist) {
-      *harq_pid = DLSCH_ptr->harq_pid_freelist[DLSCH_ptr->head_freelist];
+    if (DLSCH_ptr->harq_processes[i]->status == ACTIVE) {
+      *harq_pid = i;
+      *round = DLSCH_ptr->harq_processes[i]->round;
+    } else if (DLSCH_ptr->harq_processes[i]->status == SCH_IDLE) {
+      *harq_pid = i;
       *round = 0;
-      LOG_D(PHY,"process %d is first free process\n", *harq_pid);
+    } else {
+      printf("%s:%d: bad state for harq process - PLEASE REPORT!!\n", __FILE__, __LINE__);
+      abort();
     }
-
-    LOG_D(PHY,"get_ue_active_harq_pid DL => Frame %d, Subframe %d : harq_pid %d\n",
-	  frame,subframe,*harq_pid);
   } else { // This is a UL request
 
     ULSCH_ptr = PHY_vars_eNB_g[Mod_id][CC_id]->ulsch_eNB[(uint32_t)UE_id];
@@ -1906,7 +1854,6 @@ void process_HARQ_feedback(uint8_t UE_id,
               dlsch_harq_proc->round = 0;
               ue_stats->dlsch_l2_errors[dl_harq_pid[m]]++;
               dlsch_harq_proc->status = SCH_IDLE;
-              put_harq_pid_in_freelist(dlsch, dl_harq_pid[m]);
               dlsch->harq_ids[dl_subframe] = dlsch->Mdlharq;
             }
           } else {
@@ -1923,7 +1870,6 @@ void process_HARQ_feedback(uint8_t UE_id,
             // Received ACK so set round to 0 and set dlsch_harq_pid IDLE
             dlsch_harq_proc->round  = 0;
             dlsch_harq_proc->status = SCH_IDLE;
-            put_harq_pid_in_freelist(dlsch, dl_harq_pid[m]);
             dlsch->harq_ids[dl_subframe] = dlsch->Mdlharq;
 
             ue_stats->total_TBS = ue_stats->total_TBS +
@@ -2345,9 +2291,6 @@ void pucch_procedures(const unsigned char sched_subframe,PHY_VARS_eNB *phy_vars_
             phy_vars_eNB->eNB_UE_stats[UE_id].sr_received++;
 
             if (phy_vars_eNB->first_sr[UE_id] == 1) { // this is the first request for uplink after Connection Setup, so clear HARQ process 0 use for Msg4
-              /* is this test necessary? */
-              if (phy_vars_eNB->dlsch_eNB[UE_id][0]->harq_processes[0]->status != SCH_IDLE)
-                put_harq_pid_in_freelist(phy_vars_eNB->dlsch_eNB[UE_id][0], 0);
               phy_vars_eNB->first_sr[UE_id] = 0;
               phy_vars_eNB->dlsch_eNB[UE_id][0]->harq_processes[0]->round=0;
               phy_vars_eNB->dlsch_eNB[UE_id][0]->harq_processes[0]->status=SCH_IDLE;