Re: [RFC PATCH] linux-user: un-parent OBJECT(cpu) when closing thread

[Laurent Vivier]

On 21/06/2022 20:17, Laurent Vivier wrote:
> Le 10/06/2022 à 16:38, Alex Bennée a écrit :
> > While forcing the CPU to unrealize by hand does trigger the clean-up
> > code we never fully free resources because refcount never reaches
> > zero. This is because QOM automatically added objects without an
> > explicit parent to /unattached/, incrementing the refcount.
> >
> > Instead of manually triggering unrealization just unparent the object
> > and let the device machinery deal with that for us.
> >
> > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/866
> > Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> > ---
> >   linux-user/syscall.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > index f55cdebee5..c413d32311 100644
> > --- a/linux-user/syscall.c
> > +++ b/linux-user/syscall.c
> > @@ -8566,7 +8566,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, 
> > abi_long arg1,
> >           if (CPU_NEXT(first_cpu)) {
> >               TaskState *ts = cpu->opaque;
> > -            object_property_set_bool(OBJECT(cpu), "realized", false, NULL);
> > +            object_unparent(OBJECT(cpu));
> >               object_unref(OBJECT(cpu));
> >               /*
> >                * At this point the CPU should be unrealized and removed
>
> Applied to my linux-user-for-7.1 branch.

I remove it from the branch.

It breaks something with arm64 (only) target (any distros: stretch, sid, trusty, bionic), 
the following LTP test cases fail:

bind04, bind05, fcntl34, fcntl34_64, fcntl36, fcntl36_64, inotify09, mmap18, 
sched_setattr01, sched_getattr01, tgkill01, tgkill02, tgkill03, futex_wake02

For instance:

tst_test.c:1250: TINFO: Timeout per run is 0h 05m 00s
bind04.c:117: TINFO: Testing AF_UNIX pathname stream
bind04.c:150: TPASS: Communication successful
tst_test.c:1300: TBROK: Test killed by SIGSEGV!

Thanks,
Laurent