srsLTE/srsue/hdr/stack/mac/proc_bsr.h

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/**
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*
* \section COPYRIGHT
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*
* Copyright 2013-2020 Software Radio Systems Limited
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*
* By using this file, you agree to the terms and conditions set
* forth in the LICENSE file which can be found at the top level of
* the distribution.
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*
*/
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#ifndef SRSUE_PROC_BSR_H
#define SRSUE_PROC_BSR_H
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#include <map>
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#include <stdint.h>
#include "proc_sr.h"
#include "srslte/common/logmap.h"
#include "srslte/common/timers.h"
#include "srslte/interfaces/ue_interfaces.h"
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/* Buffer status report procedure */
namespace srsue {
// BSR interface for MUX
class bsr_interface_mux
{
public:
typedef enum { LONG_BSR, SHORT_BSR, TRUNC_BSR } bsr_format_t;
typedef struct {
bsr_format_t format;
uint32_t buff_size[4];
} bsr_t;
/* MUX calls BSR to check if it should send (and can fit) a BSR into PDU */
virtual bool need_to_send_bsr_on_ul_grant(uint32_t grant_size, uint32_t total_data, bsr_t* bsr) = 0;
/* MUX calls BSR to let it generate a padding BSR if there is space in PDU */
virtual bool generate_padding_bsr(uint32_t nof_padding_bytes, bsr_t* bsr) = 0;
proc_bsr: fix race condition in BSR reporting fix for #1934 This fixes a race condition between Stack thread and DL PDU processing that lead to updates of the RLC buffer that are undetected by the BSR routine. What happens is that in a UL SCH PDU all outstanding data is transmitted and and a LBSR with all zero buffers is sent. 14:39:47.327301 [MAC ] [D] [ 3793] BSR: LCID=3 old_buffer=59 14:39:47.330600 [MAC ] [I] [ 3793] UL LCID=3 len=58 LBSR: b=0 0 0 0 Note that "old_buffer" isn't set to zero here. At the same time (same TTI), the MAC PDU processing thread handles DL-SCH PDUs that may generate new UL PDUs: 14:39:47.330749 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=1) 14:39:47.330762 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=2) 14:39:47.330775 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=3) .. Those PDUs are "new data" since the previous buffer state was zero. Here is the race now between the threads, at the end of the bsr::step() function old_buffer of each LCG is updated with the previous new_buffer, so the buffer state of LCG=2 is now 59. Now MAC starts the next TTI: 14:39:47.331910 [MAC ] [D] [ 3794] Running MAC tti=3794 14:39:47.331928 [MAC ] [D] [ 3794] Update Bj: lcid=0, Bj=0 14:39:47.331934 [MAC ] [D] [ 3794] Update Bj: lcid=1, Bj=0 14:39:47.331938 [MAC ] [D] [ 3794] Update Bj: lcid=2, Bj=0 14:39:47.331941 [MAC ] [D] [ 3794] Update Bj: lcid=3, Bj=-1752 14:39:47.331951 [MAC ] [D] [ 3794] BSR: LCID=0 update new buffer=0 14:39:47.331960 [MAC ] [D] [ 3794] BSR: LCID=1 update new buffer=0 14:39:47.331964 [MAC ] [D] [ 3794] BSR: LCID=2 update new buffer=0 14:39:47.331971 [MAC ] [D] [ 3794] BSR: LCID=3 update new buffer=335 14:39:47.331976 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(0)=0 14:39:47.331980 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(1)=0 14:39:47.331984 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(2)=59 14:39:47.331988 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(3)=0 14:39:47.331993 [MAC ] [D] [ 3794] BSR: LCID=0 old_buffer=0 14:39:47.332000 [MAC ] [D] [ 3794] BSR: LCID=1 old_buffer=0 14:39:47.332003 [MAC ] [D] [ 3794] BSR: LCID=2 old_buffer=0 14:39:47.332007 [MAC ] [D] [ 3794] BSR: LCID=3 old_buffer=335 And since the buffer state of LCG=2 isn't zero, the new data for LCID=3 of that LCG is considered. So effectivly, the BSR missed the "empty" buffer state for a fraction of time and doesn't consider the outgoing data generated in the same TTI as new. It therefore doesn't transmit a BSR. in which a BSR wasn't
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/* MUX calls BSR to update buffer state of each LCG after all PDUs for this TTI have been packed */
virtual void update_bsr_tti_end(const bsr_t* bsr) = 0;
};
class bsr_proc : public srslte::timer_callback, public bsr_interface_mux
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{
public:
bsr_proc();
void
init(sr_proc* sr_proc, rlc_interface_mac* rlc, srslte::log_ref log_h, srslte::ext_task_sched_handle* task_sched_);
void step(uint32_t tti);
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void reset();
void set_config(srslte::bsr_cfg_t& bsr_cfg);
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void setup_lcid(uint32_t lcid, uint32_t lcg, uint32_t priority);
void timer_expired(uint32_t timer_id);
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uint32_t get_buffer_state();
bool need_to_send_bsr_on_ul_grant(uint32_t grant_size, uint32_t total_data, bsr_t* bsr);
bool generate_padding_bsr(uint32_t nof_padding_bytes, bsr_t* bsr);
proc_bsr: fix race condition in BSR reporting fix for #1934 This fixes a race condition between Stack thread and DL PDU processing that lead to updates of the RLC buffer that are undetected by the BSR routine. What happens is that in a UL SCH PDU all outstanding data is transmitted and and a LBSR with all zero buffers is sent. 14:39:47.327301 [MAC ] [D] [ 3793] BSR: LCID=3 old_buffer=59 14:39:47.330600 [MAC ] [I] [ 3793] UL LCID=3 len=58 LBSR: b=0 0 0 0 Note that "old_buffer" isn't set to zero here. At the same time (same TTI), the MAC PDU processing thread handles DL-SCH PDUs that may generate new UL PDUs: 14:39:47.330749 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=1) 14:39:47.330762 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=2) 14:39:47.330775 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=3) .. Those PDUs are "new data" since the previous buffer state was zero. Here is the race now between the threads, at the end of the bsr::step() function old_buffer of each LCG is updated with the previous new_buffer, so the buffer state of LCG=2 is now 59. Now MAC starts the next TTI: 14:39:47.331910 [MAC ] [D] [ 3794] Running MAC tti=3794 14:39:47.331928 [MAC ] [D] [ 3794] Update Bj: lcid=0, Bj=0 14:39:47.331934 [MAC ] [D] [ 3794] Update Bj: lcid=1, Bj=0 14:39:47.331938 [MAC ] [D] [ 3794] Update Bj: lcid=2, Bj=0 14:39:47.331941 [MAC ] [D] [ 3794] Update Bj: lcid=3, Bj=-1752 14:39:47.331951 [MAC ] [D] [ 3794] BSR: LCID=0 update new buffer=0 14:39:47.331960 [MAC ] [D] [ 3794] BSR: LCID=1 update new buffer=0 14:39:47.331964 [MAC ] [D] [ 3794] BSR: LCID=2 update new buffer=0 14:39:47.331971 [MAC ] [D] [ 3794] BSR: LCID=3 update new buffer=335 14:39:47.331976 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(0)=0 14:39:47.331980 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(1)=0 14:39:47.331984 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(2)=59 14:39:47.331988 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(3)=0 14:39:47.331993 [MAC ] [D] [ 3794] BSR: LCID=0 old_buffer=0 14:39:47.332000 [MAC ] [D] [ 3794] BSR: LCID=1 old_buffer=0 14:39:47.332003 [MAC ] [D] [ 3794] BSR: LCID=2 old_buffer=0 14:39:47.332007 [MAC ] [D] [ 3794] BSR: LCID=3 old_buffer=335 And since the buffer state of LCG=2 isn't zero, the new data for LCID=3 of that LCG is considered. So effectivly, the BSR missed the "empty" buffer state for a fraction of time and doesn't consider the outgoing data generated in the same TTI as new. It therefore doesn't transmit a BSR. in which a BSR wasn't
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void update_bsr_tti_end(const bsr_t* bsr);
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private:
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const static int QUEUE_STATUS_PERIOD_MS = 1000;
std::mutex mutex;
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srslte::ext_task_sched_handle* task_sched = nullptr;
srslte::log_ref log_h;
rlc_interface_mac* rlc = nullptr;
sr_proc* sr = nullptr;
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srslte::bsr_cfg_t bsr_cfg;
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bool initiated = false;
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const static int NOF_LCG = 4;
typedef struct {
int priority;
uint32_t old_buffer;
uint32_t new_buffer;
} lcid_t;
std::map<uint32_t, lcid_t> lcgs[NOF_LCG]; // groups LCID in LCG
uint32_t find_max_priority_lcg_with_data();
typedef enum { NONE, REGULAR, PADDING, PERIODIC } triggered_bsr_type_t;
triggered_bsr_type_t triggered_bsr_type = NONE;
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void print_state();
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void set_trigger(triggered_bsr_type_t new_trigger);
void update_new_data();
proc_bsr: fix race condition in BSR reporting fix for #1934 This fixes a race condition between Stack thread and DL PDU processing that lead to updates of the RLC buffer that are undetected by the BSR routine. What happens is that in a UL SCH PDU all outstanding data is transmitted and and a LBSR with all zero buffers is sent. 14:39:47.327301 [MAC ] [D] [ 3793] BSR: LCID=3 old_buffer=59 14:39:47.330600 [MAC ] [I] [ 3793] UL LCID=3 len=58 LBSR: b=0 0 0 0 Note that "old_buffer" isn't set to zero here. At the same time (same TTI), the MAC PDU processing thread handles DL-SCH PDUs that may generate new UL PDUs: 14:39:47.330749 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=1) 14:39:47.330762 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=2) 14:39:47.330775 [RLC ] [I] DRB1 Tx SDU (54 B, tx_sdu_queue_len=3) .. Those PDUs are "new data" since the previous buffer state was zero. Here is the race now between the threads, at the end of the bsr::step() function old_buffer of each LCG is updated with the previous new_buffer, so the buffer state of LCG=2 is now 59. Now MAC starts the next TTI: 14:39:47.331910 [MAC ] [D] [ 3794] Running MAC tti=3794 14:39:47.331928 [MAC ] [D] [ 3794] Update Bj: lcid=0, Bj=0 14:39:47.331934 [MAC ] [D] [ 3794] Update Bj: lcid=1, Bj=0 14:39:47.331938 [MAC ] [D] [ 3794] Update Bj: lcid=2, Bj=0 14:39:47.331941 [MAC ] [D] [ 3794] Update Bj: lcid=3, Bj=-1752 14:39:47.331951 [MAC ] [D] [ 3794] BSR: LCID=0 update new buffer=0 14:39:47.331960 [MAC ] [D] [ 3794] BSR: LCID=1 update new buffer=0 14:39:47.331964 [MAC ] [D] [ 3794] BSR: LCID=2 update new buffer=0 14:39:47.331971 [MAC ] [D] [ 3794] BSR: LCID=3 update new buffer=335 14:39:47.331976 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(0)=0 14:39:47.331980 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(1)=0 14:39:47.331984 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(2)=59 14:39:47.331988 [MAC ] [D] [ 3794] BSR: check_new_data() -> get_buffer_state_lcg(3)=0 14:39:47.331993 [MAC ] [D] [ 3794] BSR: LCID=0 old_buffer=0 14:39:47.332000 [MAC ] [D] [ 3794] BSR: LCID=1 old_buffer=0 14:39:47.332003 [MAC ] [D] [ 3794] BSR: LCID=2 old_buffer=0 14:39:47.332007 [MAC ] [D] [ 3794] BSR: LCID=3 old_buffer=335 And since the buffer state of LCG=2 isn't zero, the new data for LCID=3 of that LCG is considered. So effectivly, the BSR missed the "empty" buffer state for a fraction of time and doesn't consider the outgoing data generated in the same TTI as new. It therefore doesn't transmit a BSR. in which a BSR wasn't
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void update_old_buffer();
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bool check_highest_channel();
bool check_new_data();
bool check_any_channel();
uint32_t get_buffer_state_lcg(uint32_t lcg);
bool generate_bsr(bsr_t* bsr, uint32_t nof_padding_bytes);
char* bsr_type_tostring(triggered_bsr_type_t type);
char* bsr_format_tostring(bsr_format_t format);
srslte::timer_handler::unique_timer timer_periodic;
srslte::timer_handler::unique_timer timer_retx;
srslte::timer_handler::unique_timer timer_queue_status_print;
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};
} // namespace srsue
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#endif // SRSUE_PROC_BSR_H