Remove NR MAC's UE-specific lock

There is the (global) sched_lock that prevents concurrent access. A
dedicated UE lock does not make sense in that case. Worse, this lock
does not prevent all concurrent UE accesses (e.g., there are many loops
over UEs that are not protected), so it's also wrong.

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -2115,10 +2115,9 @@ static void nr_fill_rar(uint8_t Mod_idP, NR_UE_info_t *UE, uint8_t *dlsch_buffer
  * The corresponding function to add is add_new_UE_RA(). */
 void nr_release_ra_UE(gNB_MAC_INST *mac, rnti_t rnti)
 {
+  NR_SCHED_ENSURE_LOCKED(&mac->sched_lock);
   NR_UEs_t *UE_info = &mac->UE_info;
-  NR_SCHED_LOCK(&UE_info->mutex);
   NR_UE_info_t *UE = remove_UE_from_list(NR_NB_RA_PROC_MAX, UE_info->access_ue_list, rnti);
-  NR_SCHED_UNLOCK(&UE_info->mutex);
   if (UE) {
     delete_nr_ue_data(UE, mac->common_channels, &UE_info->uid_allocator);
   } else {

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -3033,18 +3033,17 @@ bool transition_ra_connected_nr_ue(gNB_MAC_INST *nr_mac, NR_UE_info_t *UE)
  * To remove the UE, use mac_remove_nr_ue(). */
 bool add_connected_nr_ue(gNB_MAC_INST *nr_mac, NR_UE_info_t *UE)
 {
+  NR_SCHED_ENSURE_LOCKED(&nr_mac->sched_lock);
+
   LOG_I(NR_MAC, "Adding new UE context with RNTI 0x%04x\n", UE->rnti);
   NR_UEs_t *UE_info = &nr_mac->UE_info;
   dump_nr_list(UE_info->connected_ue_list);
   AssertFatal(!UE->ra, "UE in connected cannot have RA process\n");
 
-  NR_SCHED_LOCK(&UE_info->mutex);
-
   bool success = add_UE_to_list(MAX_MOBILES_PER_GNB, UE_info->connected_ue_list, UE);
   if (!success) {
     LOG_E(NR_MAC,"Try to add UE %04x but the list is full\n", UE->rnti);
     delete_nr_ue_data(UE, NULL, &UE_info->uid_allocator);
-    NR_SCHED_UNLOCK(&UE_info->mutex);
     return false;
   }
 
@@ -3057,7 +3056,6 @@ bool add_connected_nr_ue(gNB_MAC_INST *nr_mac, NR_UE_info_t *UE)
   init_bler_stats(&nr_mac->dl_bler, &sched_ctrl->dl_bler_stats, nr_mac->frame);
   init_bler_stats(&nr_mac->ul_bler, &sched_ctrl->ul_bler_stats, nr_mac->frame);
 
-  NR_SCHED_UNLOCK(&UE_info->mutex);
   dump_nr_list(UE_info->connected_ue_list);
   return true;
 }
@@ -3110,9 +3108,7 @@ void mac_remove_nr_ue(gNB_MAC_INST *nr_mac, rnti_t rnti)
   /* already mutex protected */
   NR_SCHED_ENSURE_LOCKED(&nr_mac->sched_lock);
   NR_UEs_t *UE_info = &nr_mac->UE_info;
-  NR_SCHED_LOCK(&UE_info->mutex);
   NR_UE_info_t *UE = remove_UE_from_list(MAX_MOBILES_PER_GNB + 1, UE_info->connected_ue_list, rnti);
-  NR_SCHED_UNLOCK(&UE_info->mutex);
   if (UE)
     delete_nr_ue_data(UE, nr_mac->common_channels, &UE_info->uid_allocator);
   else

openair2/LAYER2/NR_MAC_gNB/main.c

@@ -127,7 +127,6 @@ size_t dump_mac_stats(gNB_MAC_INST *gNB, char *output, size_t strlen, bool reset
    * scheduler to be locked*/
   NR_SCHED_ENSURE_LOCKED(&gNB->sched_lock);
 
-  NR_SCHED_LOCK(&gNB->UE_info.mutex);
   UE_iterator(gNB->UE_info.connected_ue_list, UE) {
     NR_UE_sched_ctrl_t *sched_ctrl = &UE->UE_sched_ctrl;
     NR_mac_stats_t *stats = &UE->mac_stats;
@@ -237,7 +236,6 @@ size_t dump_mac_stats(gNB_MAC_INST *gNB, char *output, size_t strlen, bool reset
                          stats->ul.lc_bytes[c->lcid]);
     }
   }
-  NR_SCHED_UNLOCK(&gNB->UE_info.mutex);
   return output - begin;
 }
 
@@ -304,7 +302,6 @@ void mac_top_init_gNB(ngran_node_t node_type,
 
       pthread_mutex_init(&RC.nrmac[i]->sched_lock, NULL);
 
-      pthread_mutex_init(&RC.nrmac[i]->UE_info.mutex, NULL);
       uid_linear_allocator_init(&RC.nrmac[i]->UE_info.uid_allocator);
 
       if (get_softmodem_params()->phy_test) {

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -797,7 +797,6 @@ typedef struct {
 typedef struct {
   /// scheduling control info
   // last element always NULL
-  pthread_mutex_t mutex;
   NR_UE_info_t *connected_ue_list[MAX_MOBILES_PER_GNB + 1];
   NR_UE_info_t *access_ue_list[NR_NB_RA_PROC_MAX + 1];
   // bitmap of CSI-RS already scheduled in current slot