gtpu - added comments, updated expected construct, handled in rrc the case a gtpu teid fails to allocate

lib/include/srsran/adt/expected.h

@@ -29,7 +29,9 @@ class expected
 public:
   expected() : has_val(true), val(T{}) {}
   expected(T&& t) : has_val(true), val(std::forward<T>(t)) {}
+  expected(const T& t) : has_val(true), val(t) {}
   expected(E&& e) : has_val(false), unexpected(std::forward<E>(e)) {}
+  expected(const E& e) : has_val(false), unexpected(e) {}
   expected(const expected& other)
   {
     if (other.has_val) {

lib/include/srsran/common/buffer_pool.h

@@ -185,11 +185,17 @@ inline unique_byte_buffer_t make_byte_buffer(const char* debug_ctxt) noexcept
 }
 
 namespace detail {
+
 struct byte_buffer_pool_deleter {
   void operator()(void* ptr) { byte_buffer_pool::get_instance()->deallocate_node(ptr); }
 };
+
 } // namespace detail
 
+/**
+ * Class to wrap objects of type T which get allocated/deallocated using the byte_buffer_pool
+ * @tparam T type of the object being allocated
+ */
 template <typename T>
 struct byte_buffer_pool_ptr {
   static_assert(sizeof(T) <= byte_buffer_pool::BLOCK_SIZE, "pool_bounded_vector does not fit buffer pool block size");
@@ -202,6 +208,7 @@ public:
   const T* operator->() const { return ptr.get(); }
   T&       operator*() { return *ptr; }
   const T& operator*() const { return *ptr; }
+  bool     has_value() const { return ptr.get() != nullptr; }
 
   template <typename... CtorArgs>
   void emplace(CtorArgs&&... args)

lib/include/srsran/common/byte_buffer.h

@@ -14,6 +14,7 @@
 #define SRSRAN_BYTE_BUFFER_H
 
 #include "common.h"
+#include "srsran/adt/span.h"
 #include <chrono>
 #include <cstdint>
 

lib/include/srsran/common/common.h

@@ -17,7 +17,6 @@
                               INCLUDES
 *******************************************************************************/
 
-#include "srsran/adt/span.h"
 #include <chrono>
 #include <memory>
 #include <stdint.h>

lib/include/srsran/interfaces/enb_gtpu_interfaces.h

@@ -13,6 +13,7 @@
 #ifndef SRSRAN_ENB_GTPU_INTERFACES_H
 #define SRSRAN_ENB_GTPU_INTERFACES_H
 
+#include "srsran/adt/expected.h"
 #include "srsran/common/byte_buffer.h"
 
 namespace srsenb {
@@ -35,7 +36,7 @@ public:
     uint32_t flush_before_teidin         = 0;
   };
 
-  virtual uint32_t
+  virtual srsran::expected<uint32_t>
                add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t teid_out, const bearer_props* props = nullptr) = 0;
   virtual void set_tunnel_status(uint32_t teidin, bool dl_active)    = 0;
   virtual void rem_bearer(uint16_t rnti, uint32_t lcid)              = 0;

srsenb/hdr/stack/rrc/rrc_bearer_cfg.h

@@ -92,7 +92,7 @@ public:
 
   // Methods to apply bearer updates
   void                       add_gtpu_bearer(uint32_t erab_id);
-  uint32_t add_gtpu_bearer(uint32_t                                erab_id,
+  srsran::expected<uint32_t> add_gtpu_bearer(uint32_t                                erab_id,
                                              uint32_t                                teid_out,
                                              uint32_t                                addr,
                                              const gtpu_interface_rrc::bearer_props* props = nullptr);

srsenb/hdr/stack/upper/gtpu.h

@@ -39,10 +39,16 @@ class stack_interface_gtpu_lte;
 
 class gtpu_tunnel_manager
 {
-  using buffered_sdu_list = srsran::bounded_vector<std::pair<uint32_t, srsran::unique_byte_buffer_t>, 512>;
+  // Buffer used to store SDUs while PDCP is still getting configured during handover.
+  // Note: The buffer cannot be too large, otherwise it risks depleting the byte buffer pool.
+  const static size_t BUFFER_SIZE = 512;
+  using buffered_sdu_list = srsran::bounded_vector<std::pair<uint32_t, srsran::unique_byte_buffer_t>, BUFFER_SIZE>;
+
+  static const uint32_t undefined_pdcp_sn = std::numeric_limits<uint32_t>::max();
 
 public:
-  const static size_t MAX_TUNNELS_PER_UE = 4;
+  // A UE should have <= 3 DRBs active, and each DRB should have two tunnels active at the same time at most
+  const static size_t MAX_TUNNELS_PER_UE = 6;
 
   enum class tunnel_state { pdcp_active, buffering, forward_to, forwarded_from };
 
@@ -105,7 +111,6 @@ public:
   bool remove_rnti(uint16_t rnti);
 
 private:
-  static const uint32_t undefined_pdcp_sn = std::numeric_limits<uint32_t>::max();
   using tunnel_list_t  = srsran::static_id_obj_pool<uint32_t, tunnel, SRSENB_MAX_UES * MAX_TUNNELS_PER_UE>;
   using tunnel_ctxt_it = typename tunnel_list_t::iterator;
 
@@ -136,7 +141,7 @@ public:
   void stop();
 
   // gtpu_interface_rrc
-  uint32_t add_bearer(uint16_t            rnti,
+  srsran::expected<uint32_t> add_bearer(uint16_t            rnti,
                                         uint32_t            lcid,
                                         uint32_t            addr,
                                         uint32_t            teid_out,

srsenb/src/stack/rrc/rrc.cc

@@ -182,7 +182,6 @@ int rrc::add_user(uint16_t rnti, const sched_interface::ue_cfg_t& sched_ue_cfg)
   }
 
   if (rnti == SRSRAN_MRNTI) {
-    uint32_t teid_in = 1;
     for (auto& mbms_item : mcch.msg.c1().mbsfn_area_cfg_r9().pmch_info_list_r9[0].mbms_session_info_list_r9) {
       uint32_t lcid = mbms_item.lc_ch_id_r9;
 
@@ -190,7 +189,7 @@ int rrc::add_user(uint16_t rnti, const sched_interface::ue_cfg_t& sched_ue_cfg)
       mac->ue_cfg(SRSRAN_MRNTI, NULL);
       rlc->add_bearer_mrb(SRSRAN_MRNTI, lcid);
       pdcp->add_bearer(SRSRAN_MRNTI, lcid, srsran::make_drb_pdcp_config_t(1, false));
-      teid_in = gtpu->add_bearer(SRSRAN_MRNTI, lcid, 1, 1);
+      gtpu->add_bearer(SRSRAN_MRNTI, lcid, 1, 1);
     }
   }
   return SRSRAN_SUCCESS;

srsenb/src/stack/rrc/rrc_bearer_cfg.cc

@@ -309,14 +309,18 @@ bool bearer_cfg_handler::modify_erab(uint8_t
 void bearer_cfg_handler::add_gtpu_bearer(uint32_t erab_id)
 {
   auto it = erabs.find(erab_id);
-  if (it == erabs.end()) {
-    logger->error("Adding erab_id=%d to GTPU", erab_id);
+  if (it != erabs.end()) {
+    srsran::expected<uint32_t> teidin =
+        add_gtpu_bearer(erab_id, it->second.teid_out, it->second.address.to_number(), nullptr);
+    if (teidin.has_value()) {
+      it->second.teid_in = teidin.value();
       return;
     }
-  it->second.teid_in = add_gtpu_bearer(erab_id, it->second.teid_out, it->second.address.to_number(), nullptr);
+  }
+  logger->error("Adding erab_id=%d to GTPU", erab_id);
 }
 
-uint32_t bearer_cfg_handler::add_gtpu_bearer(uint32_t                                erab_id,
+srsran::expected<uint32_t> bearer_cfg_handler::add_gtpu_bearer(uint32_t                                erab_id,
                                                                uint32_t                                teid_out,
                                                                uint32_t                                addr,
                                                                const gtpu_interface_rrc::bearer_props* props)
@@ -324,7 +328,7 @@ uint32_t bearer_cfg_handler::add_gtpu_bearer(uint32_t
   auto it = erabs.find(erab_id);
   if (it == erabs.end()) {
     logger->error("Adding erab_id=%d to GTPU", erab_id);
-    return 0;
+    return srsran::default_error_t();
   }
 
   // Initialize ERAB tunnel in GTPU right-away. DRBs are only created during RRC setup/reconf
@@ -332,9 +336,14 @@ uint32_t bearer_cfg_handler::add_gtpu_bearer(uint32_t
   erab_t::gtpu_tunnel bearer;
   bearer.teid_out                   = teid_out;
   bearer.addr                       = addr;
-  bearer.teid_in  = gtpu->add_bearer(rnti, erab.id - 2, addr, teid_out, props);
+  srsran::expected<uint32_t> teidin = gtpu->add_bearer(rnti, erab.id - 2, addr, teid_out, props);
+  if (teidin.is_error()) {
+    logger->error("Adding erab_id=%d to GTPU", erab_id);
+    return srsran::default_error_t();
+  }
+  bearer.teid_in = teidin.value();
   erab.tunnels.push_back(bearer);
-  return bearer.teid_in;
+  return teidin;
 }
 
 void bearer_cfg_handler::rem_gtpu_bearer(uint32_t erab_id)

srsenb/src/stack/rrc/rrc_mobility.cc

@@ -784,10 +784,15 @@ void rrc::ue::rrc_mobility::handle_ho_requested(idle_st& s, const ho_req_rx_ev&
         gtpu_interface_rrc::bearer_props props;
         props.flush_before_teidin_present     = true;
         props.flush_before_teidin             = erab.second.teid_in;
-        uint32_t dl_teid_in               = rrc_ue->bearer_list.add_gtpu_bearer(
+        srsran::expected<uint32_t> dl_teid_in = rrc_ue->bearer_list.add_gtpu_bearer(
             erab.second.id, erab.second.teid_out, erab.second.address.to_number(), &props);
-        fwd_tunnels.push_back(dl_teid_in);
-        srsran::uint32_to_uint8(dl_teid_in, admitted_erabs.back().dl_g_tp_teid.data());
+        if (not dl_teid_in.has_value()) {
+          logger.error("Failed to allocate GTPU TEID");
+          trigger(srsran::failure_ev{});
+          return;
+        }
+        fwd_tunnels.push_back(dl_teid_in.value());
+        srsran::uint32_to_uint8(dl_teid_in.value(), admitted_erabs.back().dl_g_tp_teid.data());
       }
     }
   }

srsenb/src/stack/upper/gtpu.cc

@@ -414,12 +414,13 @@ void gtpu::send_pdu_to_tunnel(const gtpu_tunnel& tx_tun, srsran::unique_byte_buf
   }
 }
 
-uint32_t gtpu::add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t teid_out, const bearer_props* props)
+srsran::expected<uint32_t>
+gtpu::add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t teid_out, const bearer_props* props)
 {
   // Allocate a TEID for the incoming tunnel
   const gtpu_tunnel* new_tun = tunnels.add_tunnel(rnti, lcid, teid_out, addr);
   if (new_tun == nullptr) {
-    return -1;
+    return default_error_t();
   }
   uint32_t teid_in = new_tun->teid_in;
 
@@ -436,7 +437,7 @@ uint32_t gtpu::add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t
     if (props->forward_from_teidin_present) {
       if (create_dl_fwd_tunnel(props->forward_from_teidin, teid_in) != SRSRAN_SUCCESS) {
         rem_tunnel(teid_in);
-        return -1;
+        return default_error_t();
       }
     }
   }

srsenb/test/common/dummy_classes.h

@@ -148,10 +148,10 @@ public:
 class gtpu_dummy : public gtpu_interface_rrc
 {
 public:
-  uint32_t
+  srsran::expected<uint32_t>
   add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t teid_out, const bearer_props* props) override
   {
-    return 0;
+    return 1;
   }
   void set_tunnel_status(uint32_t teidin, bool dl_active) override {}
   void rem_bearer(uint16_t rnti, uint32_t lcid) override {}

srsenb/test/mac/sched_common_test_suite.h

@@ -15,6 +15,7 @@
 
 #include "srsenb/hdr/stack/mac/sched_common.h"
 #include "srsran/adt/bounded_bitset.h"
+#include "srsran/adt/span.h"
 #include "srsran/common/tti_point.h"
 #include "srsran/interfaces/sched_interface.h"
 

srsenb/test/upper/gtpu_test.cc

@@ -216,8 +216,8 @@ int test_gtpu_direct_tunneling(tunnel_test_event event)
   tenb_gtpu.init(tenb_addr_str, sgw_addr_str, "", "", &tenb_pdcp, &tenb_stack, false);
 
   // create tunnels MME-SeNB and MME-TeNB
-  uint32_t senb_teid_in = senb_gtpu.add_bearer(rnti, drb1, sgw_addr, sgw_teidout1);
-  uint32_t tenb_teid_in = tenb_gtpu.add_bearer(rnti2, drb1, sgw_addr, sgw_teidout2);
+  uint32_t senb_teid_in = senb_gtpu.add_bearer(rnti, drb1, sgw_addr, sgw_teidout1).value();
+  uint32_t tenb_teid_in = tenb_gtpu.add_bearer(rnti2, drb1, sgw_addr, sgw_teidout2).value();
 
   // Buffer PDUs in SeNB PDCP
   for (size_t sn = 6; sn < 10; ++sn) {
@@ -230,7 +230,7 @@ int test_gtpu_direct_tunneling(tunnel_test_event event)
   gtpu::bearer_props props;
   props.flush_before_teidin_present = true;
   props.flush_before_teidin         = tenb_teid_in;
-  uint32_t dl_tenb_teid_in          = tenb_gtpu.add_bearer(rnti2, drb1, senb_addr, 0, &props);
+  uint32_t dl_tenb_teid_in          = tenb_gtpu.add_bearer(rnti2, drb1, senb_addr, 0, &props).value();
   props                             = {};
   props.forward_from_teidin_present = true;
   props.forward_from_teidin         = senb_teid_in;