device: 0.880 performance: 0.880 graphic: 0.677 debug: 0.665 files: 0.606 boot: 0.479 network: 0.450 vnc: 0.409 semantic: 0.363 permissions: 0.326 PID: 0.287 socket: 0.169 other: 0.054 KVM: 0.020 Data Race in data->cb() call and cb assignment in test-aio-multithread Description of problem: Potential data races between the `data->cb()` call and the assignment of `cb` in `test-aio-multithread` were identified using TSAN. Steps to reproduce: ```sh QEMU_BUILD_DIR= QEMU_DIR= configure --enable-tsan --cc=clang --cxx=clang++ --enable-trace-backends=ust --enable-fdt=system --disable-slirp make tests/unit/test-bdrv-drain MALLOC_PERTURB_=102 G_TEST_SRCDIR=$QEMU_BUILD_DIR/tests/unit G_TEST_BUILDDIR=$QEMU_BUILD_DIR/tests/unit $QEMU_BUILD_DIR/tests/unit/test-aio-multithread --tap -k ```