qom: convert the CPU list to RCU

Iterating over the list without using atomics is undefined behaviour,
since the list can be modified concurrently by other threads (e.g.
every time a new thread is created in user-mode).

Fix it by implementing the CPU list as an RCU QTAILQ. This requires
a little bit of extra work to traverse list in reverse order (see
previous patch), but other than that the conversion is trivial.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20180819091335.22863-12-cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Emilio G. Cota 2018-08-19 05:13:35 -04:00 committed by Paolo Bonzini
parent 04d595b300
commit 068a5ea02f
6 changed files with 11 additions and 12 deletions

View file

@ -1096,7 +1096,7 @@ void s390_set_qemu_cpu_model(uint16_t type, uint8_t gen, uint8_t ec_ga,
const S390CPUDef *def = s390_find_cpu_def(type, gen, ec_ga, NULL);
g_assert(def);
g_assert(QTAILQ_EMPTY(&cpus));
g_assert(QTAILQ_EMPTY_RCU(&cpus));
/* TCG emulates some features that can usually not be enabled with
* the emulated machine generation. Make sure they can be enabled