[Interest] Crash in QSerialPort when closing?

[Tony Rietwyk]

Hi Sean, 

 

Closing a device within a read slot sounds dodgy anyway.  In these cases, I
usually do QTimer::singleShot(0, ...) and do the close in that slot.  

 

Regards, 

 

Tony

 

 

From: interest-bounces+tony=rightsoft.com.au at qt-project.org
[mailto:interest-bounces+tony=rightsoft.com.au at qt-project.org] On Behalf Of
Murphy, Sean
Sent: Thursday, 30 October 2014 5:36 AM
To: interest at qt-project.org
Subject: [Interest] Crash in QSerialPort when closing?

 

I'm getting a weird issue where I can repeatedly cause a crash to happen in
QSerialPort if I attempt to close the serial port when I'm in a slot
connected to the readyRead() signal, and I'm just wondering if I'm doing
something weird.

 

I've got a class that inherits from QSerialPort.  I instantiate this object
in the UI thread but immediately move it to a separate thread.  This object
has a slot, disconnectFromDevice(), that sends a reset command to the serial
device.

 

So the way I intended the software to work is the user clicks the disconnect
button in the UI thread, which sends a signal to the serial port object.
That object sends the reset command to the serial device and the serial
device responds with an acknowledge response.  The acknowledge response
triggers the QSerialPort::readyRead() signal, which triggers my readyRead()
slot.  I parse the acknowledge, then emit a signal back to the UI thread
letting the UI know that the disconnect was successful, and then call
QSerialPort::close() in the serial port object (still inside of my
readyRead() slot).  

 

When I execute setup in a debug build, at this point the application crashes
with a SIGSEV.  For some reason it kicks me into the disassembler instead of
breaking in my code.  If I comment out the close() call, the segfault
doesn't happen. 

 

Below is what's shown in the call stack, but since none of my code is shown
in the call stack, I don't know if I'm crashing on the close() call itself,
or if I crash sometime later because I'm doing something when the port isn't
open.  If I set a breakpoint anywhere in my readyRead() slot the crash
DOESN'T occur.  I only know that removing the close() call removes the
crash.

 

Any ideas?  Specifically, why am I not seeing any of my calls in the call
stack?

Sean

 

0              ReadOverlappedCompletionNotifier::processCompletionRoutine
qserialport_win.cpp       188         0x6704e8ed                

1              AbstractOverlappedEventNotifier::event
qserialport_win.cpp       119         0x6704e6d2        

2              QApplicationPrivate::notify_helper         qapplication.cpp
3467       0xa9ede0f           

3              QApplication::notify       qapplication.cpp
2888       0xa9eb72b          

4              QCoreApplication::notifyInternal
qcoreapplication.cpp      878         0x6b91b572        

5              QCoreApplication::sendEvent    qcoreapplication.h
232         0x6b9bee2b       

6              QEventDispatcherWin32Private::activateEventNotifier
qeventdispatcher_win.cpp         335         0x6b9646e8        

7              QEventDispatcherWin32::processEvents
qeventdispatcher_win.cpp         759         0x6b965de7        

8              QEventLoop::processEvents       qeventloop.cpp
136         0x6b919650        

9              QEventLoop::exec           qeventloop.cpp                212
0x6b9198eb        

10           QThread::exec  qthread.cpp       509         0x6b794f85


11           QThread::run     qthread.cpp       576         0x6b7950ed


12           QThreadPrivate::start    qthread_win.cpp             347
0x6b797ac2         

13           msvcrt!_itow_s                C:\windows\syswow64\msvcrt.dll
0x775d1287        

14           msvcrt!_endthreadex   C:\windows\syswow64\msvcrt.dll
0x775d1328        

15           KERNEL32!BaseCleanupAppcompatCacheSupport
C:\windows\syswow64\kernel32.dll                       0x7594338a


16           ??                                           0x16d0ffd4


17           ntdll!RtlpNtSetValueKey
C:\windows\system32\ntdll.dll                 0x77c19f72          

18           ??                                           0x166b7660        

19           ntdll!RtlpNtSetValueKey
C:\windows\system32\ntdll.dll                 0x77c19f45          

20           msvcrt!_endthreadex   C:\windows\syswow64\msvcrt.dll
0x775d12e5        

21           ??           

 

                                                

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