Fix SDR device lock-up from unreleased device registry on process crash

Stream threads for sensor, pager, acars, rtlamr, dmr, and dsc modes
never called release_sdr_device() when their SDR process crashed,
leaving devices permanently locked in the registry. Also fixes orphaned
companion processes (rtl_fm, rtl_tcp) not being killed on crash, start
path failures leaking processes, DMR stop handler missing lock, and
listening post/audio websocket pkill nuking all system-wide rtl_fm
processes. Wires up register_process()/unregister_process() so the
atexit/signal cleanup safety net actually works, and adds rtl_tcp,
rtl_power, rtlamr, ffmpeg to the killall endpoint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -671,7 +671,8 @@ def kill_all() -> Response:
         'rtl_fm', 'multimon-ng', 'rtl_433',
         'airodump-ng', 'aireplay-ng', 'airmon-ng',
         'dump1090', 'acarsdec', 'direwolf', 'AIS-catcher',
-        'hcitool', 'bluetoothctl', 'dsd'
+        'hcitool', 'bluetoothctl', 'dsd',
+        'rtl_tcp', 'rtl_power', 'rtlamr', 'ffmpeg',
     ]
 
     for proc in processes_to_kill:

routes/acars.py

@@ -27,6 +27,7 @@ from utils.constants import (
     SSE_QUEUE_TIMEOUT,
     PROCESS_START_WAIT,
 )
+from utils.process import register_process, unregister_process
 
 acars_bp = Blueprint('acars', __name__, url_prefix='/acars')
 
@@ -144,9 +145,24 @@ def stream_acars_output(process: subprocess.Popen, is_text_mode: bool = False) -
         logger.error(f"ACARS stream error: {e}")
         app_module.acars_queue.put({'type': 'error', 'message': str(e)})
     finally:
+        global acars_active_device
+        # Ensure process is terminated
+        try:
+            process.terminate()
+            process.wait(timeout=2)
+        except Exception:
+            try:
+                process.kill()
+            except Exception:
+                pass
+        unregister_process(process)
         app_module.acars_queue.put({'type': 'status', 'status': 'stopped'})
         with app_module.acars_lock:
             app_module.acars_process = None
+        # Release SDR device
+        if acars_active_device is not None:
+            app_module.release_sdr_device(acars_active_device)
+            acars_active_device = None
 
 
 @acars_bp.route('/tools')
@@ -311,6 +327,7 @@ def start_acars() -> Response:
             return jsonify({'status': 'error', 'message': error_msg}), 500
 
         app_module.acars_process = process
+        register_process(process)
 
         # Start output streaming thread
         thread = threading.Thread(

routes/audio_websocket.py

@@ -66,12 +66,6 @@ def kill_audio_processes():
                 pass
         rtl_process = None
 
-    # Kill any orphaned processes
-    try:
-        subprocess.run(['pkill', '-9', '-f', 'rtl_fm'], capture_output=True, timeout=1)
-    except:
-        pass
-
     time.sleep(0.3)
 
 
@@ -228,13 +222,13 @@ def init_audio_websocket(app: Flask):
 
                 except TimeoutError:
                     pass
-                except Exception as e:
-                    msg = str(e).lower()
-                    if "connection closed" in msg:
-                        logger.info("WebSocket closed by client")
-                        break
-                    if "timed out" not in msg:
-                        logger.error(f"WebSocket receive error: {e}")
+                except Exception as e:
+                    msg = str(e).lower()
+                    if "connection closed" in msg:
+                        logger.info("WebSocket closed by client")
+                        break
+                    if "timed out" not in msg:
+                        logger.error(f"WebSocket receive error: {e}")
 
                 # Stream audio data if active
                 if streaming and proc and proc.poll() is None:

routes/dmr.py

@@ -18,6 +18,7 @@ from flask import Blueprint, jsonify, request, Response
 import app as app_module
 from utils.logging import get_logger
 from utils.sse import format_sse
+from utils.process import register_process, unregister_process
 from utils.constants import (
     SSE_QUEUE_TIMEOUT,
     SSE_KEEPALIVE_INTERVAL,
@@ -244,6 +245,7 @@ def stream_dsd_output(rtl_process: subprocess.Popen, dsd_process: subprocess.Pop
     except Exception as e:
         logger.error(f"DSD stream error: {e}")
     finally:
+        global dmr_active_device, dmr_rtl_process, dmr_dsd_process
         dmr_running = False
         # Capture exit info for diagnostics
         rc = dsd_process.poll()
@@ -258,7 +260,26 @@ def stream_dsd_output(rtl_process: subprocess.Popen, dsd_process: subprocess.Pop
             except Exception:
                 pass
             logger.warning(f"DSD process exited with code {rc}: {detail}")
+        # Cleanup both processes
+        for proc in [dsd_process, rtl_process]:
+            if proc and proc.poll() is None:
+                try:
+                    proc.terminate()
+                    proc.wait(timeout=2)
+                except Exception:
+                    try:
+                        proc.kill()
+                    except Exception:
+                        pass
+            if proc:
+                unregister_process(proc)
+        dmr_rtl_process = None
+        dmr_dsd_process = None
         _queue_put({'type': 'status', 'text': reason, 'exit_code': rc, 'detail': detail})
+        # Release SDR device
+        if dmr_active_device is not None:
+            app_module.release_sdr_device(dmr_active_device)
+            dmr_active_device = None
         logger.info("DSD stream thread stopped")
 
 
@@ -354,6 +375,7 @@ def start_dmr() -> Response:
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
+        register_process(dmr_rtl_process)
 
         dmr_dsd_process = subprocess.Popen(
             dsd_cmd,
@@ -361,6 +383,7 @@ def start_dmr() -> Response:
             stdout=subprocess.DEVNULL,
             stderr=subprocess.PIPE,
         )
+        register_process(dmr_dsd_process)
 
         # Allow rtl_fm to send directly to dsd
         dmr_rtl_process.stdout.close()
@@ -428,21 +451,24 @@ def stop_dmr() -> Response:
     """Stop digital voice decoding."""
     global dmr_rtl_process, dmr_dsd_process, dmr_running, dmr_active_device
 
-    dmr_running = False
+    with dmr_lock:
+        dmr_running = False
 
-    for proc in [dmr_dsd_process, dmr_rtl_process]:
-        if proc and proc.poll() is None:
-            try:
-                proc.terminate()
-                proc.wait(timeout=2)
-            except Exception:
+        for proc in [dmr_dsd_process, dmr_rtl_process]:
+            if proc and proc.poll() is None:
                 try:
-                    proc.kill()
+                    proc.terminate()
+                    proc.wait(timeout=2)
                 except Exception:
-                    pass
+                    try:
+                        proc.kill()
+                    except Exception:
+                        pass
+            if proc:
+                unregister_process(proc)
 
-    dmr_rtl_process = None
-    dmr_dsd_process = None
+        dmr_rtl_process = None
+        dmr_dsd_process = None
 
     if dmr_active_device is not None:
         app_module.release_sdr_device(dmr_active_device)

routes/dsc.py

@@ -39,6 +39,7 @@ from utils.sse import format_sse
 from utils.validation import validate_device_index, validate_gain
 from utils.sdr import SDRFactory, SDRType
 from utils.dependencies import get_tool_path
+from utils.process import register_process, unregister_process
 
 logger = logging.getLogger('intercept.dsc')
 
@@ -169,17 +170,34 @@ def stream_dsc_decoder(master_fd: int, decoder_process: subprocess.Popen) -> Non
             'error': str(e)
         })
     finally:
+        global dsc_active_device
         try:
             os.close(master_fd)
         except OSError:
             pass
-        decoder_process.wait()
         dsc_running = False
+        # Cleanup both processes
+        with app_module.dsc_lock:
+            rtl_proc = app_module.dsc_rtl_process
+        for proc in [rtl_proc, decoder_process]:
+            if proc:
+                try:
+                    proc.terminate()
+                    proc.wait(timeout=2)
+                except Exception:
+                    try:
+                        proc.kill()
+                    except Exception:
+                        pass
+                unregister_process(proc)
         app_module.dsc_queue.put({'type': 'status', 'status': 'stopped'})
-
         with app_module.dsc_lock:
             app_module.dsc_process = None
             app_module.dsc_rtl_process = None
+        # Release SDR device
+        if dsc_active_device is not None:
+            app_module.release_sdr_device(dsc_active_device)
+            dsc_active_device = None
 
 
 def _store_critical_alert(msg: dict) -> None:
@@ -362,6 +380,7 @@ def start_decoding() -> Response:
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE
             )
+            register_process(rtl_process)
 
             # Start stderr monitor thread
             stderr_thread = threading.Thread(
@@ -382,6 +401,7 @@ def start_decoding() -> Response:
                 stderr=slave_fd,
                 close_fds=True
             )
+            register_process(decoder_process)
 
             os.close(slave_fd)
             rtl_process.stdout.close()
@@ -408,6 +428,15 @@ def start_decoding() -> Response:
             })
 
         except FileNotFoundError as e:
+            # Kill orphaned rtl_fm process
+            try:
+                rtl_process.terminate()
+                rtl_process.wait(timeout=2)
+            except Exception:
+                try:
+                    rtl_process.kill()
+                except Exception:
+                    pass
             # Release device on failure
             if dsc_active_device is not None:
                 app_module.release_sdr_device(dsc_active_device)
@@ -417,6 +446,15 @@ def start_decoding() -> Response:
                 'message': f'Tool not found: {e.filename}'
             }), 400
         except Exception as e:
+            # Kill orphaned rtl_fm process if it was started
+            try:
+                rtl_process.terminate()
+                rtl_process.wait(timeout=2)
+            except Exception:
+                try:
+                    rtl_process.kill()
+                except Exception:
+                    pass
             # Release device on failure
             if dsc_active_device is not None:
                 app_module.release_sdr_device(dsc_active_device)

routes/listening_post.py

@@ -891,17 +891,6 @@ def _stop_audio_stream_internal():
     audio_process = None
     audio_rtl_process = None
 
-    # Kill any orphaned rtl_fm, rtl_power, and ffmpeg processes
-    for proc_pattern in ['rtl_fm', 'rtl_power']:
-        try:
-            subprocess.run(['pkill', '-9', proc_pattern], capture_output=True, timeout=0.5)
-        except Exception:
-            pass
-    try:
-        subprocess.run(['pkill', '-9', '-f', 'ffmpeg.*pipe:0'], capture_output=True, timeout=0.5)
-    except Exception:
-        pass
-
     # Pause for SDR device USB interface to be released by kernel
     time.sleep(1.0)
 

routes/pager.py

@@ -23,7 +23,7 @@ from utils.validation import (
     validate_rtl_tcp_host, validate_rtl_tcp_port
 )
 from utils.sse import format_sse
-from utils.process import safe_terminate, register_process
+from utils.process import safe_terminate, register_process, unregister_process
 from utils.sdr import SDRFactory, SDRType, SDRValidationError
 from utils.dependencies import get_tool_path
 
@@ -146,14 +146,32 @@ def stream_decoder(master_fd: int, process: subprocess.Popen[bytes]) -> None:
     except Exception as e:
         app_module.output_queue.put({'type': 'error', 'text': str(e)})
     finally:
+        global pager_active_device
         try:
             os.close(master_fd)
         except OSError:
             pass
-        process.wait()
+        # Cleanup companion rtl_fm process and decoder
+        with app_module.process_lock:
+            rtl_proc = getattr(app_module.current_process, '_rtl_process', None)
+        for proc in [rtl_proc, process]:
+            if proc:
+                try:
+                    proc.terminate()
+                    proc.wait(timeout=2)
+                except Exception:
+                    try:
+                        proc.kill()
+                    except Exception:
+                        pass
+                unregister_process(proc)
         app_module.output_queue.put({'type': 'status', 'text': 'stopped'})
         with app_module.process_lock:
             app_module.current_process = None
+        # Release SDR device
+        if pager_active_device is not None:
+            app_module.release_sdr_device(pager_active_device)
+            pager_active_device = None
 
 
 @pager_bp.route('/start', methods=['POST'])
@@ -281,6 +299,7 @@ def start_decoding() -> Response:
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE
             )
+            register_process(rtl_process)
 
             # Start a thread to monitor rtl_fm stderr for errors
             def monitor_rtl_stderr():
@@ -304,6 +323,7 @@ def start_decoding() -> Response:
                 stderr=slave_fd,
                 close_fds=True
             )
+            register_process(multimon_process)
 
             os.close(slave_fd)
             rtl_process.stdout.close()
@@ -322,12 +342,30 @@ def start_decoding() -> Response:
             return jsonify({'status': 'started', 'command': full_cmd})
 
         except FileNotFoundError as e:
+            # Kill orphaned rtl_fm process
+            try:
+                rtl_process.terminate()
+                rtl_process.wait(timeout=2)
+            except Exception:
+                try:
+                    rtl_process.kill()
+                except Exception:
+                    pass
             # Release device on failure
             if pager_active_device is not None:
                 app_module.release_sdr_device(pager_active_device)
                 pager_active_device = None
             return jsonify({'status': 'error', 'message': f'Tool not found: {e.filename}'})
         except Exception as e:
+            # Kill orphaned rtl_fm process if it was started
+            try:
+                rtl_process.terminate()
+                rtl_process.wait(timeout=2)
+            except Exception:
+                try:
+                    rtl_process.kill()
+                except Exception:
+                    pass
             # Release device on failure
             if pager_active_device is not None:
                 app_module.release_sdr_device(pager_active_device)

routes/rtlamr.py

@@ -18,7 +18,7 @@ from utils.validation import (
     validate_frequency, validate_device_index, validate_gain, validate_ppm
 )
 from utils.sse import format_sse
-from utils.process import safe_terminate, register_process
+from utils.process import safe_terminate, register_process, unregister_process
 
 rtlamr_bp = Blueprint('rtlamr', __name__)
 
@@ -61,10 +61,37 @@ def stream_rtlamr_output(process: subprocess.Popen[bytes]) -> None:
     except Exception as e:
         app_module.rtlamr_queue.put({'type': 'error', 'text': str(e)})
     finally:
-        process.wait()
+        global rtl_tcp_process, rtlamr_active_device
+        # Ensure rtlamr process is terminated
+        try:
+            process.terminate()
+            process.wait(timeout=2)
+        except Exception:
+            try:
+                process.kill()
+            except Exception:
+                pass
+        unregister_process(process)
+        # Kill companion rtl_tcp process
+        with rtl_tcp_lock:
+            if rtl_tcp_process:
+                try:
+                    rtl_tcp_process.terminate()
+                    rtl_tcp_process.wait(timeout=2)
+                except Exception:
+                    try:
+                        rtl_tcp_process.kill()
+                    except Exception:
+                        pass
+                unregister_process(rtl_tcp_process)
+                rtl_tcp_process = None
         app_module.rtlamr_queue.put({'type': 'status', 'text': 'stopped'})
         with app_module.rtlamr_lock:
             app_module.rtlamr_process = None
+        # Release SDR device
+        if rtlamr_active_device is not None:
+            app_module.release_sdr_device(rtlamr_active_device)
+            rtlamr_active_device = None
 
 
 @rtlamr_bp.route('/start_rtlamr', methods=['POST'])
@@ -133,7 +160,8 @@ def start_rtlamr() -> Response:
                         stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE
                     )
-                    
+                    register_process(rtl_tcp_process)
+
                     # Wait a moment for rtl_tcp to start
                     time.sleep(3)
                     
@@ -141,6 +169,10 @@ def start_rtlamr() -> Response:
                     app_module.rtlamr_queue.put({'type': 'info', 'text': f'rtl_tcp: {" ".join(rtl_tcp_cmd)}'})
                 except Exception as e:
                     logger.error(f"Failed to start rtl_tcp: {e}")
+                    # Release SDR device on rtl_tcp failure
+                    if rtlamr_active_device is not None:
+                        app_module.release_sdr_device(rtlamr_active_device)
+                        rtlamr_active_device = None
                     return jsonify({'status': 'error', 'message': f'Failed to start rtl_tcp: {e}'}), 500
 
         # Build rtlamr command
@@ -174,6 +206,7 @@ def start_rtlamr() -> Response:
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE
             )
+            register_process(app_module.rtlamr_process)
 
             # Start output thread
             thread = threading.Thread(target=stream_rtlamr_output, args=(app_module.rtlamr_process,))

routes/sensor.py

@@ -19,7 +19,7 @@ from utils.validation import (
     validate_rtl_tcp_host, validate_rtl_tcp_port
 )
 from utils.sse import format_sse
-from utils.process import safe_terminate, register_process
+from utils.process import safe_terminate, register_process, unregister_process
 from utils.sdr import SDRFactory, SDRType
 
 sensor_bp = Blueprint('sensor', __name__)
@@ -59,10 +59,24 @@ def stream_sensor_output(process: subprocess.Popen[bytes]) -> None:
     except Exception as e:
         app_module.sensor_queue.put({'type': 'error', 'text': str(e)})
     finally:
-        process.wait()
+        global sensor_active_device
+        # Ensure process is terminated
+        try:
+            process.terminate()
+            process.wait(timeout=2)
+        except Exception:
+            try:
+                process.kill()
+            except Exception:
+                pass
+        unregister_process(process)
         app_module.sensor_queue.put({'type': 'status', 'text': 'stopped'})
         with app_module.sensor_lock:
             app_module.sensor_process = None
+        # Release SDR device
+        if sensor_active_device is not None:
+            app_module.release_sdr_device(sensor_active_device)
+            sensor_active_device = None
 
 
 @sensor_bp.route('/start_sensor', methods=['POST'])
@@ -149,6 +163,7 @@ def start_sensor() -> Response:
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE
             )
+            register_process(app_module.sensor_process)
 
             # Start output thread
             thread = threading.Thread(target=stream_sensor_output, args=(app_module.sensor_process,))