diff options
author | Thiago Macieira <thiago.macieira@intel.com> | 2020-04-02 12:08:41 -0300 |
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committer | Thiago Macieira <thiago.macieira@intel.com> | 2020-04-06 13:27:05 +0000 |
commit | 276fa8383a7535765be7182883ef4aade17ce013 (patch) | |
tree | 46ee05335c117293da8f1b712b4b4d0e22d7c7d6 /src/corelib/plugin/qlibrary_unix.cpp | |
parent | 615204e0762c2e12077e8c8dd3c6d29b9648f163 (diff) |
QLibrary: fix deadlock caused by fix to QTBUG-39642
Commit ae6f73e8566fa76470937aca737141183929a5ec inserted a mutex around
the entire load_sys(). We had reasoed that deadlocks would only occur if
the object creation in instance() recursed into its own instance(),
which was already a bug. But we had forgotten that dlopen()/
LoadLibrary() executes initialization code from the module being loaded,
which could cause a recursion back into the same QPluginLoader or
QLibrary object. This recursion is benign because the module *is* loaded
and dlopen()/LoadLibrary() returns the same handle.
[ChangeLog][QtCore][QLibrary and QPluginLoader] Fixed a deadlock that
would happen if the plugin or library being loaded has load-time
initialization code (C++ global variables) that recursed back into the
same QLibrary or QPluginLoader object.
PS: QLibraryPrivate::loadPlugin() updates pluginState outside a mutex
lock, so pluginState should be made an atomic variable. Once that is
done, we'll only need locking the mutex to update errorString (no
locking before loading).
Fixes: QTBUG-83207
Task-number: QTBUG-39642
Change-Id: Ibdc95e9af7bd456a94ecfffd160209304e5ab2eb
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: David Faure <david.faure@kdab.com>
Diffstat (limited to 'src/corelib/plugin/qlibrary_unix.cpp')
-rw-r--r-- | src/corelib/plugin/qlibrary_unix.cpp | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/corelib/plugin/qlibrary_unix.cpp b/src/corelib/plugin/qlibrary_unix.cpp index 017aa97b66..a5c72f81d9 100644 --- a/src/corelib/plugin/qlibrary_unix.cpp +++ b/src/corelib/plugin/qlibrary_unix.cpp @@ -123,6 +123,7 @@ QStringList QLibraryPrivate::prefixes_sys() bool QLibraryPrivate::load_sys() { + QMutexLocker locker(&mutex); QString attempt; QFileSystemEntry fsEntry(fileName); @@ -213,6 +214,7 @@ bool QLibraryPrivate::load_sys() } #endif + locker.unlock(); bool retry = true; Handle hnd = nullptr; for (int prefix = 0; retry && !hnd && prefix < prefixes.size(); prefix++) { @@ -273,6 +275,8 @@ bool QLibraryPrivate::load_sys() } } #endif + + locker.relock(); if (!hnd) { errorString = QLibrary::tr("Cannot load library %1: %2").arg(fileName, qdlerror()); } |