tsan does not recognize QMutex

[ramosian-glider]

Originally reported on Google Code with ID 53

What steps will reproduce the problem?

Compile and run the test program below.


What is the expected output? What do you see instead?

Tsan should recognize the QMutex as a synchronizing mechanism and not print a warning.
The example works like expected using ab boost:mutex instead.


What version of the product are you using? On what operating system?

llvm-3.4 on centos-6.5 x86_64


Please provide any additional information below.


    #include <QtConcurrentRun>
    #include <QMutex>
    #include <iostream>
    #include <boost/thread/mutex.hpp>

    class TestClass
    {
    public:
     void fun()
     {
      QMutexLocker autoMutex(&mutex);
      //boost::mutex::scoped_lock bautoMutex(bmutex);
      data = 1;
     }
    private:
     int data;
     QMutex mutex;
     boost::mutex bmutex;
    };

    int main()
    {
     TestClass *tc = new TestClass;

     QFuture<void> t1 = QtConcurrent::run(tc, &TestClass::fun);
     QFuture<void> t2 = QtConcurrent::run(tc, &TestClass::fun);

     t1.waitForFinished();
     t2.waitForFinished();

     return 0;
    }

Reported by benjamin.firl@wincor-nixdorf.com on 2014-03-10 13:10:29

[ramosian-glider]

Hi,

Thanks for the report.

Does QT accept patches from community?

Please also file an issue against QT. Let's see what interest are there.

Reported by dvyukov@google.com on 2014-03-11 06:08:52

• Labels added: Type-Enhancement
• Labels removed: Type-Defect

[ramosian-glider]

The Qt bug report was closed because it's "not our issue": https://bugreports.qt.io/browse/QTBUG-37402

However they do accept patches if someone is able to fix the issue in the way they
want you to...

Reported by cbparker on 2015-02-02 08:37:35

[ramosian-glider]

Is there a way to annotate QMutex for ThreadSanitizer to understand it? If so, then
I'd add such code to Qt Base when defined(__has_feature) && __has_feature(thread_sanitizer).


If there is no such thing, and I cannot find any headers with macros I could use for
that purpose, can someone point me to the sources in TSan (in data-race-test, right?)
that need to be patched to add support for QMutex?

Reported by milian.wolff@kdab.com on 2015-07-16 16:29:43

[ramosian-glider]

Hi milian.wolff,

Yes, tsan supports annotations for mutexes:
https://code.google.com/p/data-race-test/source/browse/trunk/dynamic_annotations/dynamic_annotations.h
They are implemented in tsan here:
http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interface_ann.cc?view=markup

In particular you want:
AnnotateRWLockCreate(char *f, int l, uptr m)
AnnotateRWLockDestroy(char *f, int l, uptr m)
AnnotateRWLockAcquired(char *f, int l, uptr m, uptr is_w)
AnnotateRWLockReleased(char *f, int l, uptr m, uptr is_w)

f is file name (__FILE__)
l is line (__LINE__)
m is mutex address
is_w is whether mutexes is locked in write mode or in read mode

AnnotateRWLockAcquired must be called after the actual acquire.
AnnotateRWLockReleased must be called right before the mutex is actually unlocked.

Reported by dvyukov@google.com on 2015-07-16 20:46:36

[ramosian-glider]

GCC does not seem to support the __has_feature check for TSan - is there an alternative
to detect it there?

Reported by milian.wolff@kdab.com on 2015-07-20 10:31:09

[ramosian-glider]

The attached file works fine with clang++, but in GCC it does not work at all. Note
that I rely instead on a define (QT_SANITIZE_THREAD) to be set, instead of the __has_feature
which is also not supported by GCC.

I thought GCC and clang share the same TSan, but this here shows that apparently this
is it not the case. Is there any way to fix this also for GCC?

Reported by milian.wolff@kdab.com on 2015-07-20 12:53:52

[ramosian-glider]

Internally at Google we define THREAD_SANITIZER macro when tsan is enabled, and check
that macro.

You can file a bug against gcc, but as far as I remember they intentionally did not
implement it.

Reported by dvyukov@google.com on 2015-07-20 18:09:29

[ramosian-glider]

Yuri, do you know any way to detect if a sanitizer is enabled or not in gcc?

Reported by dvyukov@google.com on 2015-07-20 18:10:19

[ramosian-glider]

OK, I can add a similar macro. But the annotations don't work there - should they? I'm
using GCC 5.1.0.

Reported by milian.wolff@kdab.com on 2015-07-21 14:26:32

[ramosian-glider]

gcc should support these annotations as well.
Please show how you annotate, and how exactly annotation don't work (don't compile?
don't link?).

Reported by dvyukov@google.com on 2015-07-22 06:25:25

[ramosian-glider]

Adding Project:ThreadSanitizer as part of GitHub migration.

Reported by glider@google.com on 2015-07-30 09:21:31

• Labels added: ProjectThreadSanitizer

[dvyukov]

not actionable on our side