Details
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Bug
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Resolution: Cannot Reproduce
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P3: Somewhat important
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None
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5.12.4
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None
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Windows 10 x64 1803
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Windows
Description
Consider the following scenario:
Use a computer with an ethernet connection with internet access with this setup:
PC - ethernet cable 1- ethernet switch - ethernet cable 2 - internet gateway
We do this so that Windows will not immediately detect that the ethernet interface is down when we unplug ethernet cable 2.
Procedure: Now make sure you have internet access on your PC. Disable your ethernet interface, wait for a few seconds then enable it. Check that internet is working, then unplug ethernet cable 2, then launch the application.
The application calls get() of QNetworkAccessManager then prints "Not frozen".
The application hangs at the get() call of QNetworkAccessManager, the console won't output anything, if you try to exit it, it will display a mutex issue. Running it again will show "Not frozen".
To reproduce again, perform again the procedure
I have compiled this in debug mode and interrupted the process, here is the call stack:
1 NtWaitForSingleObject ntdll 0x7ffd67fcaa24 2 WaitForSingleObjectEx KERNELBASE 0x7ffd64339252 3 QMutexPrivate::wait qmutex_win.cpp 64 0x7ffd1335bf5c 4 QBasicMutex::lockInternal qmutex.cpp 573 0x7ffd1335b8c4 5 QBasicMutex::lockInternal qmutex.cpp 490 0x7ffd1335b658 6 QBasicMutex::lock qmutex.h 80 0x7ffd13320184 7 QRecursiveMutexPrivate::lock qmutex.cpp 707 0x7ffd1335d69f 8 QMutex::lock qmutex.cpp 226 0x7ffd1335bd51 9 QMutexLocker::QMutexLocker qmutex.h 207 0x7ffd1331a48d 10 QSslSocketPrivate::ensureLibraryLoaded qsslsocket_openssl11.cpp 90 0x7ffd168cdbf1 11 QSslSocketPrivate::supportsSsl qsslsocket_openssl.cpp 497 0x7ffd168b7f79 12 QSslSocketPrivate::ensureInitialized qsslsocket_openssl.cpp 509 0x7ffd168b7fe9 13 QSslConfigurationPrivate::defaultConfiguration qsslsocket.cpp 2280 0x7ffd168980fe 14 QSslConfiguration::defaultConfiguration qsslconfiguration.cpp 1023 0x7ffd16887233 15 QNetworkRequest::sslConfiguration qnetworkrequest.cpp 675 0x7ffd1671eccb 16 QNetworkReplyHttpImpl::QNetworkReplyHttpImpl qnetworkreplyhttpimpl.cpp 193 0x7ffd167d04ae 17 QNetworkAccessManager::createRequest qnetworkaccessmanager.cpp 1480 0x7ffd166f5f72 18 QNetworkAccessManager::post qnetworkaccessmanager.cpp 882 0x7ffd166f3f02 19 QNetworkAccessManager::post qnetworkaccessmanager.cpp 897 0x7ffd166f3fe9 20 ApiConnectorMgr::postPingData ApiConnectorMgr.cpp 572 0x7ff7815613ab 21 ApiConnectorMgr::updateCloudServerStatus ApiConnectorMgr.cpp 1078 0x7ff7815614ce 22 ApiConnectorMgr::ApiConnectorMgr ApiConnectorMgr.cpp 58 0x7ff781556f18 23 MainWindow::MainWindow mainwindow.cpp 121 0x7ff78143bbf8 24 main main.cpp 122 0x7ff781438636 25 invoke_main exe_common.inl 65 0x7ff781598274 26 __scrt_common_main_seh exe_common.inl 253 0x7ff781598137 27 __scrt_common_main exe_common.inl 296 0x7ff781597ffe 28 mainCRTStartup exe_main.cpp 17 0x7ff781598299 29 BaseThreadInitThunk KERNEL32 0x7ffd67e54034 30 RtlUserThreadStart ntdll 0x7ffd67fa3691
The lock seems to come from a QMutexLocker in qsslsocket_openssl11.cpp
qsslsocket_openssl11.cpp line 83
bool QSslSocketPrivate::ensureLibraryLoaded()
{
if (!q_resolveOpenSslSymbols())
return false;
const QMutexLocker locker(qt_opensslInitMutex);
[interrupted here]
-> if (!s_libraryLoaded) {
// Initialize OpenSSL.
if (q_OPENSSL_init_ssl(0, nullptr) != 1)
return false;
q_SSL_load_error_strings();
q_OpenSSL_add_all_algorithms();
QSslSocketBackendPrivate::s_indexForSSLExtraData
= q_CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_SSL, 0L, nullptr, nullptr,
nullptr, nullptr);
// Initialize OpenSSL's random seed.
if (!q_RAND_status()) {
qWarning("Random number generator not seeded, disabling SSL support");
return false;
}
s_libraryLoaded = true;
}
return true;
}