FlexRAN: implement possibilty to await a configuration

Through configuration, the lte-softmodem can be halted to await a
reconfiguration from the lte-softmodem. A mutex and condition variable are used
to implement this.

Furthermore, the dependance of lte-softmodem.c on FlexRAN has been reduced to
one include and the flexran_agent_start() call.

openair2/ENB_APP/enb_config.c

@@ -267,7 +267,7 @@ void RCconfig_flexran()
     RC.flexran[i]->remote_port      = *(flexranParams[FLEXRAN_PORT_IDX].uptr);
     // DEFAULT_FLEXRAN_AGENT_CACHE
     RC.flexran[i]->cache_name       = strdup(*(flexranParams[FLEXRAN_CACHE_IDX].strptr));
-    RC.flexran[i]->await_reconf     = strcmp(*(flexranParams[FLEXRAN_AWAIT_RECONF_IDX].strptr), "yes") == 0;
+    RC.flexran[i]->node_ctrl_state  = strcmp(*(flexranParams[FLEXRAN_AWAIT_RECONF_IDX].strptr), "yes") == 0 ? ENB_WAIT : ENB_NORMAL_OPERATION;
     RC.flexran[i]->enb_id           = i;
   }
 

openair2/ENB_APP/flexran_agent.c

@@ -180,14 +180,15 @@ pthread_t new_thread(void *(*f)(void *), void *b) {
 int channel_container_init = 0;
 int flexran_agent_start(mid_t mod_id)
 {
+  flexran_agent_info_t *flexran = RC.flexran[mod_id];
   int channel_id;
-  char *in_ip = RC.flexran[mod_id]->remote_ipv4_addr;
-  uint16_t in_port = RC.flexran[mod_id]->remote_port;
+  char *in_ip = flexran->remote_ipv4_addr;
+  uint16_t in_port = flexran->remote_port;
   
-  RC.flexran[mod_id]->enb_id = mod_id;
+  flexran->enb_id = mod_id;
   /* assume for the moment the monolithic case, i.e. agent can provide
    * information for all layers */
-  RC.flexran[mod_id]->capability_mask = FLEXRAN_CAP_LOL1 | FLEXRAN_CAP_HIL1
+  flexran->capability_mask = FLEXRAN_CAP_LOL1 | FLEXRAN_CAP_HIL1
                            | FLEXRAN_CAP_LOL2 | FLEXRAN_CAP_HIL2
                            | FLEXRAN_CAP_PDCP | FLEXRAN_CAP_RRC;
 
@@ -228,7 +229,7 @@ int flexran_agent_start(mid_t mod_id)
   /*Initialize the continuous stats update mechanism*/
   flexran_agent_init_cont_stats_update(mod_id);
   
-  new_thread(receive_thread, RC.flexran[mod_id]);
+  new_thread(receive_thread, flexran);
 
   /*Initialize and register the mac xface. Must be modified later
    *for more flexibility in agent management */
@@ -257,14 +258,34 @@ int flexran_agent_start(mid_t mod_id)
    * start the enb agent task for tx and interaction with the underlying network function
    */ 
   if (!agent_task_created) {
-    if (itti_create_task (TASK_FLEXRAN_AGENT, flexran_agent_task, (void *) RC.flexran[mod_id]) < 0) {
+    if (itti_create_task (TASK_FLEXRAN_AGENT, flexran_agent_task, flexran) < 0) {
       LOG_E(FLEXRAN_AGENT, "Create task for FlexRAN Agent failed\n");
       return -1;
     }
     agent_task_created = 1;
   }
 
-  LOG_I(FLEXRAN_AGENT,"client ends\n");
+  pthread_mutex_init(&flexran->mutex_node_ctrl, NULL);
+  pthread_cond_init(&flexran->cond_node_ctrl, NULL);
+
+  if (flexran->node_ctrl_state == ENB_WAIT) {
+    /* wait three seconds before showing message and waiting "for real".
+     * This way, the message is (hopefully...) the last one and the user knows
+     * what is happening. If the controller sends a reconfiguration message in
+     * the meantime, the softmodem will never wait */
+    sleep(3);
+    LOG_I(ENB_APP, " * eNB %d: Waiting for FlexRAN RTController command *\n", mod_id);
+    pthread_mutex_lock(&flexran->mutex_node_ctrl);
+    while (ENB_NORMAL_OPERATION != flexran->node_ctrl_state)
+      pthread_cond_wait(&flexran->cond_node_ctrl, &flexran->mutex_node_ctrl);
+    pthread_mutex_unlock(&flexran->mutex_node_ctrl);
+
+    /* reconfigure RRC again, the agent might have changed the configuration */
+    MessageDef *msg_p = itti_alloc_new_message(TASK_ENB_APP, RRC_CONFIGURATION_REQ);
+    RRC_CONFIGURATION_REQ(msg_p) = RC.rrc[mod_id]->configuration;
+    itti_send_msg_to_task(TASK_RRC_ENB, ENB_MODULE_ID_TO_INSTANCE(mod_id), msg_p);
+  }
+
   return 0;
 
 error:

openair2/ENB_APP/flexran_agent.h

@@ -42,12 +42,8 @@
 #include "log.h"
 #include "assertions.h"
 
-#include "enb_config.h" // for enb properties
-
-
-/* Initiation and termination of the eNodeB agent */
+/* Initiation of the eNodeB agent */
 int flexran_agent_start(mid_t mod_id);
-int flexran_agent_stop(mid_t mod_id);
 
 /* 
  * enb agent task mainly wakes up the tx thread for periodic and oneshot messages to the controller 

openair2/ENB_APP/flexran_agent_common_internal.c

@@ -39,13 +39,32 @@ void handle_reconfiguration(mid_t mod_id)
 {
   struct timespec start, end;
   clock_gettime(CLOCK_MONOTONIC, &start);
+  flexran_agent_info_t *flexran = RC.flexran[mod_id];
+
+  if (ENB_WAIT == flexran->node_ctrl_state) {
+    /* this is already waiting, just release */
+    pthread_mutex_lock(&flexran->mutex_node_ctrl);
+    flexran->node_ctrl_state = ENB_NORMAL_OPERATION;
+    pthread_mutex_unlock(&flexran->mutex_node_ctrl);
+    pthread_cond_signal(&flexran->cond_node_ctrl);
+    return;
+  }
 
   if (stop_L1L2(mod_id) < 0) {
     LOG_E(ENB_APP, "can not stop lte-softmodem, aborting restart\n");
     return;
   }
 
-  /* TODO wait state could be here IF IT IS NOT EXECUTED BY THE FLEXRAN THREAD */
+  /* node_ctrl_state should have value ENB_MAKE_WAIT only if this method is not
+   * executed by the FlexRAN thread */
+  if (ENB_MAKE_WAIT == flexran->node_ctrl_state) {
+    LOG_I(ENB_APP, " * eNB %d: Waiting for FlexRAN RTController command *\n", mod_id);
+    pthread_mutex_lock(&flexran->mutex_node_ctrl);
+    flexran->node_ctrl_state = ENB_WAIT;
+    while (ENB_NORMAL_OPERATION != flexran->node_ctrl_state)
+      pthread_cond_wait(&flexran->cond_node_ctrl, &flexran->mutex_node_ctrl);
+    pthread_mutex_unlock(&flexran->mutex_node_ctrl);
+  }
 
   if (restart_L1L2(mod_id) < 0) {
     LOG_F(ENB_APP, "can not restart, killing lte-softmodem\n");

openair2/ENB_APP/flexran_agent_defs.h

@@ -145,17 +145,27 @@ typedef enum {
 #define FLEXRAN_CAP_PDCP 0x16
 #define FLEXRAN_CAP_RRC  0x32
 
+typedef enum {
+  ENB_NORMAL_OPERATION = 0x0,
+  ENB_WAIT             = 0x1,
+  ENB_MAKE_WAIT        = 0x2,
+} flexran_enb_state_t;
+
 typedef struct {
   /* general info */ 
   char    *interface_name;
   char    *remote_ipv4_addr;
   uint16_t remote_port;
   char    *cache_name;
-  uint8_t  await_reconf;
 
   int      enb_id;
   uint8_t  capability_mask;
 
+  /* lock for waiting before starting or soft-restart */
+  pthread_cond_t      cond_node_ctrl;
+  pthread_mutex_t     mutex_node_ctrl;
+  flexran_enb_state_t node_ctrl_state;
+
   /* stats */
 
   uint32_t total_rx_msg;

targets/RT/USER/lte-softmodem.c

@@ -1149,26 +1149,6 @@ int main( int argc, char **argv )
 
   for (CC_id=0; CC_id<MAX_NUM_CCs; CC_id++) {
 
-#ifdef FLEXRAN_AGENT_SB_IF
-    pthread_mutex_init(&mutex_node_ctrl, NULL);
-    pthread_cond_init(&cond_node_ctrl, NULL);
-
-    /* create RC.flexran data structure */
-    RCconfig_flexran();
-    for (i = 0; i < RC.nb_L1_inst; i++) {
-      flexran_agent_start(i);
-    }
-
-    /* TODO handle restart/initial blocking */
-    //LOG_I(ENB_APP, " * Waiting for FlexRAN RTController command *\n");
-    //pthread_mutex_lock(&mutex_node_ctrl);
-    //while (ENB_NORMAL_OPERATION != node_control_state)
-    //  pthread_cond_wait(&cond_node_ctrl, &mutex_node_ctrl);
-    //pthread_mutex_unlock(&mutex_node_ctrl);
-
-    /* TODO do eNB reconfiguration (handled implicitly?) */
-#endif
-
     if (UE_flag==1) {     
       NB_UE_INST=1;     
       NB_INST=1;     
@@ -1292,6 +1272,12 @@ int main( int argc, char **argv )
   }
 #endif
 
+#ifdef FLEXRAN_AGENT_SB_IF
+    RCconfig_flexran();
+    for (i = 0; i < RC.nb_L1_inst; i++) {
+      flexran_agent_start(i);
+    }
+#endif
   
   mlockall(MCL_CURRENT | MCL_FUTURE);
   
@@ -1507,11 +1493,6 @@ int main( int argc, char **argv )
   pthread_cond_destroy(&sync_cond);
   pthread_mutex_destroy(&sync_mutex);
 
-#ifdef FLEXRAN_AGENT_SB_IF
-    pthread_cond_destroy(&cond_node_ctrl);
-    pthread_mutex_destroy(&mutex_node_ctrl);
-#endif
-
   // *** Handle per CC_id openair0
   if (UE_flag==1) {
     if (PHY_vars_UE_g[0][0]->rfdevice.trx_end_func)

targets/RT/USER/lte-softmodem.h

@@ -272,10 +272,7 @@ extern int stop_L1L2(module_id_t enb_id);
 extern int restart_L1L2(module_id_t enb_id);
 
 #ifdef FLEXRAN_AGENT_SB_IF
-#include "flexran_agent.h" // for locking
-//volatile ENB_MODULE_STATE node_control_state;
-pthread_cond_t cond_node_ctrl;
-pthread_mutex_t mutex_node_ctrl;
+#include "flexran_agent.h"
 #endif
 
 #endif