QMutex: Make freelist() return a real global static

Since Qt 5.6.0, some applications such as Kate (built with clang, libc++
and libcxxrt) on FreeBSD occasionally crash with the following error
message on exit:

    QMutex::lock(): sem_wait failure: Invalid argument
    [or pthread_cond_wait in the 5.6 branch]

Investigation by Gleb Popov, Thiago Macieira and Olivier Goffart has
shown that this is caused by the fact that QDBusConnectionManager is a
Q_GLOBAL_STATIC (so it will be destroyed with all the other
Q_GLOBAL_STATICs in the reverse order of construction). In the
Q_COMPILER_THREADSAFE_STATICS case, freelist() also returns a
function-level static that is constructed on first use, so it may be
destroyed earlier than the QDBusConnectionManager object, making it
impossible to lock a contended mutex.

We now make freelist() return a global static, so that it is always
destroyed after QDBusConnectionManager and other function-static
variables.

Change-Id: I210fa7c18dbdf2345863da49141b9a85cffdef52
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

0 files changed, 0 insertions, 0 deletions