From fa4d14652de0482b94b08df1f16a5a03899a124c Mon Sep 17 00:00:00 2001
From: Ismael Gomez <ismagom@gmail.com>
Date: Wed, 21 Mar 2018 13:32:19 +0100
Subject: [PATCH] Added mutex for ue_rem/buffer access for more safety

---
 srsenb/hdr/mac/scheduler.h  |  6 +++---
 srsenb/src/mac/scheduler.cc | 24 ++++++++++++++++++------
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/srsenb/hdr/mac/scheduler.h b/srsenb/hdr/mac/scheduler.h
index c3ca7d624..12c336c36 100644
--- a/srsenb/hdr/mac/scheduler.h
+++ b/srsenb/hdr/mac/scheduler.h
@@ -100,8 +100,8 @@ public:
   uint32_t get_ul_buffer(uint16_t rnti); 
   uint32_t get_dl_buffer(uint16_t rnti); 
 
-  int dl_rlc_buffer_state(uint16_t rnti, uint32_t lc_id, uint32_t tx_queue, uint32_t retx_queue); 
-  int dl_mac_buffer_state(uint16_t rnti, uint32_t ce_code); 
+  int dl_rlc_buffer_state(uint16_t rnti, uint32_t lc_id, uint32_t tx_queue, uint32_t retx_queue);
+  int dl_mac_buffer_state(uint16_t rnti, uint32_t ce_code);
     
   int dl_ant_info(uint16_t rnti, LIBLTE_RRC_ANTENNA_INFO_DEDICATED_STRUCT *dedicated);
   int dl_ack_info(uint32_t tti, uint16_t rnti, uint32_t tb_idx, bool ack);
@@ -217,7 +217,7 @@ private:
   
   bool configured;
   
-  pthread_mutex_t mutex; 
+  pthread_mutex_t mutex, mutex2;
   
   
 };
diff --git a/srsenb/src/mac/scheduler.cc b/srsenb/src/mac/scheduler.cc
index 995363045..2e0504193 100644
--- a/srsenb/src/mac/scheduler.cc
+++ b/srsenb/src/mac/scheduler.cc
@@ -64,6 +64,7 @@ sched::sched() : bc_aggr_level(0), rar_aggr_level(0), avail_rbg(0), P(0), start_
   }
 
   pthread_mutex_init(&mutex, NULL);
+  pthread_mutex_init(&mutex2, NULL);
   reset();
 }
 
@@ -71,6 +72,7 @@ sched::~sched()
 {
   srslte_regs_free(&regs);
   pthread_mutex_destroy(&mutex);
+  pthread_mutex_destroy(&mutex2);
 }
 
 void sched::init(rrc_interface_mac *rrc_, srslte::log* log)
@@ -173,13 +175,15 @@ int sched::ue_cfg(uint16_t rnti, sched_interface::ue_cfg_t *ue_cfg)
 int sched::ue_rem(uint16_t rnti)
 {
   pthread_mutex_lock(&mutex);
-  int ret = 0; 
+  pthread_mutex_lock(&mutex2);
+  int ret = 0;
   if (ue_db.count(rnti)) {         
     ue_db.erase(rnti);
   } else {
     Error("User rnti=0x%x not found\n", rnti);
     ret = -1;
   }
+  pthread_mutex_unlock(&mutex2);
   pthread_mutex_unlock(&mutex);
   return ret; 
 }
@@ -217,13 +221,15 @@ int sched::bearer_ue_cfg(uint16_t rnti, uint32_t lc_id, sched_interface::ue_bear
 int sched::bearer_ue_rem(uint16_t rnti, uint32_t lc_id)
 {
   pthread_mutex_lock(&mutex);
-  int ret = 0; 
+  pthread_mutex_lock(&mutex2);
+  int ret = 0;
   if (ue_db.count(rnti)) {         
     ue_db[rnti].rem_bearer(lc_id);
   } else {
     Error("User rnti=0x%x not found\n", rnti);
     ret = -1;
   }
+  pthread_mutex_unlock(&mutex2);
   pthread_mutex_unlock(&mutex);
   return ret; 
 }
@@ -259,9 +265,13 @@ uint32_t sched::get_ul_buffer(uint16_t rnti)
  * 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
+ *
+ * We add a new mutex used only in ue_rem to avoid the UE being removed in between the access to
+ * ue_db.count() and the access to the std::map.
  */
 int sched::dl_rlc_buffer_state(uint16_t rnti, uint32_t lc_id, uint32_t tx_queue, uint32_t retx_queue)
 {
+  pthread_mutex_lock(&mutex2);
   int ret = 0;
   if (ue_db.count(rnti)) {
     ue_db[rnti].dl_buffer_state(lc_id, tx_queue, retx_queue);
@@ -269,21 +279,23 @@ int sched::dl_rlc_buffer_state(uint16_t rnti, uint32_t lc_id, uint32_t tx_queue,
     Error("User rnti=0x%x not found\n", rnti);
     ret = -1;
   }
+  pthread_mutex_unlock(&mutex2);
   return ret;
 }
 
+/* \Warning Read comment in dl_rlc_buffer_state() */
 int sched::dl_mac_buffer_state(uint16_t rnti, uint32_t ce_code)
 {
-  pthread_mutex_lock(&mutex);
-  int ret = 0; 
+  pthread_mutex_lock(&mutex2);
+  int ret = 0;
   if (ue_db.count(rnti)) {         
     ue_db[rnti].mac_buffer_state(ce_code);
   } else {
     Error("User rnti=0x%x not found\n", rnti);
     ret = -1;
   }
-  pthread_mutex_unlock(&mutex);
-  return ret; 
+  pthread_mutex_unlock(&mutex2);
+  return ret;
 }
 
 int sched::dl_ant_info(uint16_t rnti, LIBLTE_RRC_ANTENNA_INFO_DEDICATED_STRUCT *dl_ant_info) {