diff --git a/lib/include/srsran/common/interfaces_common.h b/lib/include/srsran/common/interfaces_common.h
index 5997e63b1..ce7996205 100644
--- a/lib/include/srsran/common/interfaces_common.h
+++ b/lib/include/srsran/common/interfaces_common.h
@@ -77,7 +77,7 @@ public:
 class read_pdu_interface
 {
 public:
-  virtual int read_pdu(uint32_t lcid, uint8_t* payload, uint32_t requested_bytes) = 0;
+  virtual uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t requested_bytes) = 0;
 };
 
 class stack_interface_phy_nr
diff --git a/lib/include/srsran/interfaces/ue_rlc_interfaces.h b/lib/include/srsran/interfaces/ue_rlc_interfaces.h
index c7f05dd42..4c6452138 100644
--- a/lib/include/srsran/interfaces/ue_rlc_interfaces.h
+++ b/lib/include/srsran/interfaces/ue_rlc_interfaces.h
@@ -67,7 +67,7 @@ public:
 
   /* MAC calls RLC to get RLC segment of nof_bytes length.
    * Segmentation happens in this function. RLC PDU is stored in payload. */
-  virtual int read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) = 0;
+  virtual uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) = 0;
 
   /* MAC calls RLC to push an RLC PDU. This function is called from an independent MAC thread.
    * PDU gets placed into the buffer and higher layer thread gets notified. */
diff --git a/lib/include/srsran/test/ue_test_interfaces.h b/lib/include/srsran/test/ue_test_interfaces.h
index 4263eb6b8..0b7ad541f 100644
--- a/lib/include/srsran/test/ue_test_interfaces.h
+++ b/lib/include/srsran/test/ue_test_interfaces.h
@@ -50,7 +50,7 @@ class rlc_dummy_interface : public rlc_interface_mac
 public:
   bool     has_data_locked(const uint32_t lcid) override { return false; }
   uint32_t get_buffer_state(const uint32_t lcid) override { return 0; }
-  int      read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) override { return 0; }
+  uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) override { return 0; }
   void     write_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) override {}
   void     write_pdu_bcch_bch(srsran::unique_byte_buffer_t payload) override {}
   void     write_pdu_bcch_dlsch(uint8_t* payload, uint32_t nof_bytes) override {}
diff --git a/lib/include/srsran/upper/rlc.h b/lib/include/srsran/upper/rlc.h
index 75fff9a98..cb393a26e 100644
--- a/lib/include/srsran/upper/rlc.h
+++ b/lib/include/srsran/upper/rlc.h
@@ -66,8 +66,8 @@ public:
   bool     has_data_locked(const uint32_t lcid);
   uint32_t get_buffer_state(const uint32_t lcid);
   uint32_t get_total_mch_buffer_state(uint32_t lcid);
-  int      read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes);
-  int      read_pdu_mch(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes);
+  uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes);
+  uint32_t read_pdu_mch(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes);
   int      get_increment_sequence_num();
   void     write_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes);
   void     write_pdu_bcch_bch(srsran::unique_byte_buffer_t pdu);
diff --git a/lib/include/srsran/upper/rlc_am_lte.h b/lib/include/srsran/upper/rlc_am_lte.h
index d5afc0aa4..e3f316b07 100644
--- a/lib/include/srsran/upper/rlc_am_lte.h
+++ b/lib/include/srsran/upper/rlc_am_lte.h
@@ -345,7 +345,7 @@ public:
   // MAC interface
   bool     has_data();
   uint32_t get_buffer_state();
-  int      read_pdu(uint8_t* payload, uint32_t nof_bytes);
+  uint32_t read_pdu(uint8_t* payload, uint32_t nof_bytes);
   void     write_pdu(uint8_t* payload, uint32_t nof_bytes);
 
   rlc_bearer_metrics_t get_metrics();
@@ -368,7 +368,7 @@ private:
     void stop();
 
     int  write_sdu(unique_byte_buffer_t sdu);
-    int  read_pdu(uint8_t* payload, uint32_t nof_bytes);
+    uint32_t read_pdu(uint8_t* payload, uint32_t nof_bytes);
     void discard_sdu(uint32_t discard_sn);
     bool sdu_queue_is_full();
 
diff --git a/lib/include/srsran/upper/rlc_common.h b/lib/include/srsran/upper/rlc_common.h
index 44568cec7..fcbbf33e1 100644
--- a/lib/include/srsran/upper/rlc_common.h
+++ b/lib/include/srsran/upper/rlc_common.h
@@ -274,7 +274,7 @@ public:
   virtual bool     has_data() = 0;
   bool             is_suspended() { return suspended; };
   virtual uint32_t get_buffer_state()                              = 0;
-  virtual int      read_pdu(uint8_t* payload, uint32_t nof_bytes)  = 0;
+  virtual uint32_t read_pdu(uint8_t* payload, uint32_t nof_bytes)  = 0;
   virtual void     write_pdu(uint8_t* payload, uint32_t nof_bytes) = 0;
 
   virtual void set_bsr_callback(bsr_callback_t callback) = 0;
@@ -320,4 +320,5 @@ private:
 };
 
 } // namespace srsran
+
 #endif // SRSRAN_RLC_COMMON_H
diff --git a/lib/include/srsran/upper/rlc_tm.h b/lib/include/srsran/upper/rlc_tm.h
index d4890db70..b5db8fd67 100644
--- a/lib/include/srsran/upper/rlc_tm.h
+++ b/lib/include/srsran/upper/rlc_tm.h
@@ -54,7 +54,7 @@ public:
   // MAC interface
   bool     has_data() override;
   uint32_t get_buffer_state() override;
-  int      read_pdu(uint8_t* payload, uint32_t nof_bytes) override;
+  uint32_t read_pdu(uint8_t* payload, uint32_t nof_bytes) override;
   void     write_pdu(uint8_t* payload, uint32_t nof_bytes) override;
 
   void set_bsr_callback(bsr_callback_t callback) override {}
diff --git a/lib/include/srsran/upper/rlc_um_base.h b/lib/include/srsran/upper/rlc_um_base.h
index 1094b7cff..b17357a38 100644
--- a/lib/include/srsran/upper/rlc_um_base.h
+++ b/lib/include/srsran/upper/rlc_um_base.h
@@ -58,7 +58,7 @@ public:
   // MAC interface
   bool     has_data();
   uint32_t get_buffer_state();
-  int      read_pdu(uint8_t* payload, uint32_t nof_bytes);
+  uint32_t read_pdu(uint8_t* payload, uint32_t nof_bytes);
   void     write_pdu(uint8_t* payload, uint32_t nof_bytes);
   int      get_increment_sequence_num();
 
@@ -75,7 +75,7 @@ protected:
     rlc_um_base_tx(rlc_um_base* parent_);
     virtual ~rlc_um_base_tx();
     virtual bool     configure(const rlc_config_t& cfg, std::string rb_name) = 0;
-    int              build_data_pdu(uint8_t* payload, uint32_t nof_bytes);
+    uint32_t         build_data_pdu(uint8_t* payload, uint32_t nof_bytes);
     void             stop();
     void             reestablish();
     void             empty_queue();
@@ -107,7 +107,7 @@ protected:
     srsran::rolling_average<double> mean_pdu_latency_us;
 #endif
 
-    virtual int build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes) = 0;
+    virtual uint32_t build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes) = 0;
 
     // helper functions
     virtual void debug_state() = 0;
diff --git a/lib/include/srsran/upper/rlc_um_lte.h b/lib/include/srsran/upper/rlc_um_lte.h
index f544c582e..17bf8ccb9 100644
--- a/lib/include/srsran/upper/rlc_um_lte.h
+++ b/lib/include/srsran/upper/rlc_um_lte.h
@@ -48,7 +48,7 @@ private:
     rlc_um_lte_tx(rlc_um_base* parent_);
 
     bool     configure(const rlc_config_t& cfg, std::string rb_name);
-    int      build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes);
+    uint32_t build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes);
     uint32_t get_buffer_state();
     bool     sdu_queue_is_full();
 
diff --git a/lib/include/srsran/upper/rlc_um_nr.h b/lib/include/srsran/upper/rlc_um_nr.h
index 5d01b40d4..6c5e4936e 100644
--- a/lib/include/srsran/upper/rlc_um_nr.h
+++ b/lib/include/srsran/upper/rlc_um_nr.h
@@ -49,7 +49,7 @@ private:
     rlc_um_nr_tx(rlc_um_base* parent_);
 
     bool     configure(const rlc_config_t& cfg, std::string rb_name);
-    int      build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes);
+    uint32_t build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes);
     uint32_t get_buffer_state();
 
   private:
diff --git a/lib/src/upper/rlc.cc b/lib/src/upper/rlc.cc
index 76836800e..d24dae789 100644
--- a/lib/src/upper/rlc.cc
+++ b/lib/src/upper/rlc.cc
@@ -292,7 +292,7 @@ uint32_t rlc::get_total_mch_buffer_state(uint32_t lcid)
   return ret;
 }
 
-int rlc::read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc::read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
 {
   uint32_t ret = 0;
 
@@ -309,7 +309,7 @@ int rlc::read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
   return ret;
 }
 
-int rlc::read_pdu_mch(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc::read_pdu_mch(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
 {
   uint32_t ret = 0;
 
diff --git a/lib/src/upper/rlc_am_lte.cc b/lib/src/upper/rlc_am_lte.cc
index 8590d0b91..45079e826 100644
--- a/lib/src/upper/rlc_am_lte.cc
+++ b/lib/src/upper/rlc_am_lte.cc
@@ -248,9 +248,9 @@ uint32_t rlc_am_lte::get_buffer_state()
   return tx.get_buffer_state();
 }
 
-int rlc_am_lte::read_pdu(uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_am_lte::read_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
-  int read_bytes = tx.read_pdu(payload, nof_bytes);
+  uint32_t read_bytes = tx.read_pdu(payload, nof_bytes);
   metrics.num_tx_pdus++;
   metrics.num_tx_pdu_bytes += read_bytes;
   return read_bytes;
@@ -533,7 +533,7 @@ bool rlc_am_lte::rlc_am_lte_tx::sdu_queue_is_full()
   return tx_sdu_queue.is_full();
 }
 
-int rlc_am_lte::rlc_am_lte_tx::read_pdu(uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_am_lte::rlc_am_lte_tx::read_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
   std::lock_guard<std::mutex> lock(mutex);
 
diff --git a/lib/src/upper/rlc_tm.cc b/lib/src/upper/rlc_tm.cc
index e1da8b802..776d2b3cf 100644
--- a/lib/src/upper/rlc_tm.cc
+++ b/lib/src/upper/rlc_tm.cc
@@ -134,12 +134,12 @@ void rlc_tm::reset_metrics()
   metrics = {};
 }
 
-int rlc_tm::read_pdu(uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_tm::read_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
   uint32_t pdu_size = ul_queue.size_tail_bytes();
   if (pdu_size > nof_bytes) {
     logger.info("%s Tx PDU size larger than MAC opportunity (%d > %d)", rrc->get_rb_name(lcid), pdu_size, nof_bytes);
-    return -1;
+    return 0;
   }
   unique_byte_buffer_t buf;
   if (ul_queue.try_read(&buf)) {
@@ -171,7 +171,7 @@ int rlc_tm::read_pdu(uint8_t* payload, uint32_t nof_bytes)
 void rlc_tm::write_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
   unique_byte_buffer_t buf = make_byte_buffer();
-  if (buf) {
+  if (buf != nullptr) {
     memcpy(buf->msg, payload, nof_bytes);
     buf->N_bytes = nof_bytes;
     buf->set_timestamp();
diff --git a/lib/src/upper/rlc_um_base.cc b/lib/src/upper/rlc_um_base.cc
index 5155ca31e..1ac0d183b 100644
--- a/lib/src/upper/rlc_um_base.cc
+++ b/lib/src/upper/rlc_um_base.cc
@@ -130,7 +130,7 @@ uint32_t rlc_um_base::get_buffer_state()
   return 0;
 }
 
-int rlc_um_base::read_pdu(uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_um_base::read_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
   if (tx && tx_enabled) {
     uint32_t len = tx->build_data_pdu(payload, nof_bytes);
@@ -283,7 +283,7 @@ bool rlc_um_base::rlc_um_base_tx::sdu_queue_is_full()
   return tx_sdu_queue.is_full();
 }
 
-int rlc_um_base::rlc_um_base_tx::build_data_pdu(uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_um_base::rlc_um_base_tx::build_data_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
   unique_byte_buffer_t pdu;
   {
diff --git a/lib/src/upper/rlc_um_lte.cc b/lib/src/upper/rlc_um_lte.cc
index 004787c12..cbfe56e4c 100644
--- a/lib/src/upper/rlc_um_lte.cc
+++ b/lib/src/upper/rlc_um_lte.cc
@@ -109,7 +109,7 @@ bool rlc_um_lte::rlc_um_lte_tx::configure(const rlc_config_t& cnfg_, std::string
   return true;
 }
 
-int rlc_um_lte::rlc_um_lte_tx::build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_um_lte::rlc_um_lte_tx::build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes)
 {
   std::lock_guard<std::mutex> lock(mutex);
   rlc_umd_pdu_header_t        header;
diff --git a/lib/src/upper/rlc_um_nr.cc b/lib/src/upper/rlc_um_nr.cc
index 1c88f3aaa..1cf1aa4af 100644
--- a/lib/src/upper/rlc_um_nr.cc
+++ b/lib/src/upper/rlc_um_nr.cc
@@ -115,7 +115,7 @@ bool rlc_um_nr::rlc_um_nr_tx::configure(const rlc_config_t& cnfg_, std::string r
   return true;
 }
 
-int rlc_um_nr::rlc_um_nr_tx::build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes)
+uint32_t rlc_um_nr::rlc_um_nr_tx::build_data_pdu(unique_byte_buffer_t pdu, uint8_t* payload, uint32_t nof_bytes)
 {
   // Sanity check (we need at least 2B for a SDU)
   if (nof_bytes < 2) {
diff --git a/lib/test/mac/pdu_test.cc b/lib/test/mac/pdu_test.cc
index 13296205b..4f10332f5 100644
--- a/lib/test/mac/pdu_test.cc
+++ b/lib/test/mac/pdu_test.cc
@@ -169,7 +169,7 @@ int mac_rar_pdu_pack_test2()
 class rlc_dummy : public srsran::read_pdu_interface
 {
 public:
-  int read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
+  uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes)
   {
     uint32_t len = std::min(ul_queues[lcid], nof_bytes);
 
diff --git a/srsenb/hdr/stack/mac/ue.h b/srsenb/hdr/stack/mac/ue.h
index abd30bee2..7e7a945d1 100644
--- a/srsenb/hdr/stack/mac/ue.h
+++ b/srsenb/hdr/stack/mac/ue.h
@@ -175,7 +175,7 @@ public:
   void metrics_dl_cqi(uint32_t dl_cqi);
   void metrics_cnt();
 
-  int read_pdu(uint32_t lcid, uint8_t* payload, uint32_t requested_bytes) final;
+  uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t requested_bytes) final;
 
 private:
   void allocate_sdu(srsran::sch_pdu* pdu, uint32_t lcid, uint32_t sdu_len);
diff --git a/srsenb/src/stack/mac/ue.cc b/srsenb/src/stack/mac/ue.cc
index 20435213a..0bc539178 100644
--- a/srsenb/src/stack/mac/ue.cc
+++ b/srsenb/src/stack/mac/ue.cc
@@ -503,7 +503,7 @@ bool ue::process_ce(srsran::sch_subh* subh, int grant_nof_prbs)
   return is_bsr;
 }
 
-int ue::read_pdu(uint32_t lcid, uint8_t* payload, uint32_t requested_bytes)
+uint32_t ue::read_pdu(uint32_t lcid, uint8_t* payload, uint32_t requested_bytes)
 {
   return rlc->read_pdu(rnti, lcid, payload, requested_bytes);
 }
diff --git a/srsue/src/stack/mac_nr/test/mac_nr_test.cc b/srsue/src/stack/mac_nr/test/mac_nr_test.cc
index ad685e63e..315581f92 100644
--- a/srsue/src/stack/mac_nr/test/mac_nr_test.cc
+++ b/srsue/src/stack/mac_nr/test/mac_nr_test.cc
@@ -92,7 +92,7 @@ public:
   rlc_dummy() : received_bytes(0) {}
   bool     has_data_locked(const uint32_t lcid) final { return ul_queues[lcid] > 0; }
   uint32_t get_buffer_state(const uint32_t lcid) final { return ul_queues[lcid]; }
-  int      read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) final
+  uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) final
   {
     if (!read_enable || nof_bytes < read_min) {
       return 0;
diff --git a/srsue/test/mac_test.cc b/srsue/test/mac_test.cc
index 9d2b65b13..ba81533fe 100644
--- a/srsue/test/mac_test.cc
+++ b/srsue/test/mac_test.cc
@@ -37,7 +37,7 @@ public:
   rlc_dummy() : received_bytes(0) {}
   bool     has_data_locked(const uint32_t lcid) final { return ul_queues[lcid] > 0; }
   uint32_t get_buffer_state(const uint32_t lcid) final { return ul_queues[lcid]; }
-  int      read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) final
+  uint32_t read_pdu(uint32_t lcid, uint8_t* payload, uint32_t nof_bytes) final
   {
     if (!read_enable || nof_bytes < read_min) {
       return 0;