Changeset f61257601 in mythtv

Timestamp:

07/24/12 16:13:16 (5 years ago)

Author:

Daniel Thor Kristjansson <dkristjansson@…>

Branches:

master, beta/0.28, devel/027candidates, devel/dbus-screensaver, devel/eit-encoding-fixes, devel/ffmpeg-resync, devel/housekeeper, devel/http_ssl, devel/iptv, devel/logging, devel/lvr/rpi, devel/lvr/startup, devel/mythsocket, devel/mythsystem, devel/newvaapi, devel/opengl, devel/resync-ffmpeg28, devel/rpi, devel/scheduler, fixes/0.27, fixes/0.28, fixes/29, personal/stuartm/mheg-debug

Children:

50957d5b6

Parents:

38257011f7

git-author:

Daniel Thor Kristjansson <dkristjansson@…> (07/24/12 16:13:16)

git-committer:

Daniel Thor Kristjansson <dkristjansson@…> (07/24/12 16:13:16)

Message:

Fixes #10870. Fix Start/Stop? race condition in StreamHandler?.

Take two... The locking order documented in streamhandler.h wasn't being adhered to
in the DVBStreamHandler. The actual locking order is now documented and a new lock
has been added for AddListener/RemoveListener? as per the suggested code from Roger
James.

Location:

mythtv/libs/libmythtv/recorders

Files:

• streamhandler.cpp (modified) (5 diffs)
• streamhandler.h (modified) (2 diffs)

mythtv/libs/libmythtv/recorders/streamhandler.cpp

@@ -27 +27 @@
 StreamHandler::~StreamHandler()
 {
-    if (!_stream_data_list.empty())
-    {
-        LOG(VB_GENERAL, LOG_ERR, LOC + "dtor & _stream_data_list not empty");
+    QMutexLocker locker(&_add_rm_lock);
+
+    {
+        QMutexLocker locker2(&_listener_lock);
+        if (!_stream_data_list.empty())
+        {
+            LOG(VB_GENERAL, LOG_ERR, LOC +
+                "dtor & _stream_data_list not empty");
+        }
     }
 
@@ -42 +48 @@
                                 QString output_file)
 {
+    QMutexLocker locker(&_add_rm_lock);
+
     LOG(VB_RECORD, LOG_INFO, LOC + QString("AddListener(0x%1) -- begin")
                 .arg((uint64_t)data,0,16));
@@ -94 +102 @@
 void StreamHandler::RemoveListener(MPEGStreamData *data)
 {
+    QMutexLocker locker(&_add_rm_lock);
+
     LOG(VB_RECORD, LOG_INFO, LOC + QString("RemoveListener(0x%1) -- begin")
                 .arg((uint64_t)data,0,16));
@@ -159 +169 @@
         _running_state_changed.wait(&_start_stop_lock, 100);
 
-    if (!_running_desired)
-    {
-        LOG(VB_GENERAL, LOG_WARNING, LOC +
-            "Programmer Error: Stop called before Start finished");
-    }
-
     if (_error)
     {
@@ -176 +180 @@
     QMutexLocker locker(&_start_stop_lock);
 
-    do
-    {
-        SetRunningDesired(false);
-        while (!_running_desired && _running)
-            _running_state_changed.wait(&_start_stop_lock, 100);
-        if (_running_desired)
-        {
-            LOG(VB_GENERAL, LOG_WARNING, LOC +
-                "Programmer Error: Start called before Stop finished");
-        }
-    } while (_running_desired);
+    SetRunningDesired(false);
+    while (_running)
+        _running_state_changed.wait(&_start_stop_lock, 100);
 
     wait();

mythtv/libs/libmythtv/recorders/streamhandler.h

@@ -46 +46 @@
 
 // locking order
-// _pid_lock -> _listener_lock -> _start_stop_lock
+// _pid_lock -> _listener_lock
+// _add_rm_lock -> _listener_lock
+//              -> _start_stop_lock
 
 class StreamHandler : protected MThread, public DeviceReaderCB
@@ -102 +104 @@
     bool              _allow_section_reader;
 
+    QMutex            _add_rm_lock;
+
     mutable QMutex    _start_stop_lock;
     volatile bool     _running_desired;