On Mon, 16 Oct 2017 10:41:39 +0200
Igor Mammedov <imamm...@redhat.com> wrote:
> On Fri, 13 Oct 2017 13:47:51 +0200
> Greg Kurz <gr...@kaod.org> wrote:
>
> [...]
>
> > Note that the resolution should really return a CPU object, otherwise
> > we have a bug. This is achieved by relying on object_resolve_path()
> > and CPU() instead of calling object_resolve_path_type(path, TYPE_CPU).
> I'm not sure what you are trying to say here, could you explain
> a bit more why CPU(object_resolve_path()) is chosen vs
> object_resolve_path_type(path, TYPE_CPU)
>
IIUC, if we use object_resolve_path_type(path, TYPE_CPU) and path doesn't
point to a CPU object, it will return NULL (see object_resolve_abs_path())
just like if the CPU got hot-unplugged.
My point is that the path we got from object_get_canonical_path() did
point to a CPU: if later on this path resolves to an object that isn't
a CPU, then some code somewhere used the same QOM path for some unrelated
object. I tend to think this is a bug in QEMU and we shouldn't silently
ignore it.
Makes sense ?
>
> > Suggested-by: Igor Mammedov <imamm...@redhat.com>
> > Signed-off-by: Greg Kurz <gr...@kaod.org>
> > ---
> > monitor.c | 25 ++++++++++++++++++++-----
> > 1 file changed, 20 insertions(+), 5 deletions(-)
> >
> > diff --git a/monitor.c b/monitor.c
> > index fe0d1bdbb461..8489b2ad99c0 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -200,7 +200,7 @@ struct Monitor {
> >
> > ReadLineState *rs;
> > MonitorQMP qmp;
> > - CPUState *mon_cpu;
> > + gchar *mon_cpu_path;
> > BlockCompletionFunc *password_completion_cb;
> > void *password_opaque;
> > mon_cmd_t *cmd_table;
> > @@ -579,6 +579,7 @@ static void monitor_data_init(Monitor *mon)
> >
> > static void monitor_data_destroy(Monitor *mon)
> > {
> > + g_free(mon->mon_cpu_path);
> > qemu_chr_fe_deinit(&mon->chr, false);
> > if (monitor_is_qmp(mon)) {
> > json_message_parser_destroy(&mon->qmp.parser);
> > @@ -1047,20 +1048,34 @@ int monitor_set_cpu(int cpu_index)
> > if (cpu == NULL) {
> > return -1;
> > }
> > - cur_mon->mon_cpu = cpu;
> > + g_free(cur_mon->mon_cpu_path);
> > + cur_mon->mon_cpu_path = object_get_canonical_path(OBJECT(cpu));
> > return 0;
> > }
> >
> > CPUState *mon_get_cpu(void)
> > {
> > - if (!cur_mon->mon_cpu) {
> > + CPUState *cpu;
> > +
> > + if (cur_mon->mon_cpu_path) {
> > + Object *obj = object_resolve_path(cur_mon->mon_cpu_path, NULL);
> > +
> > + if (!obj) {
> > + g_free(cur_mon->mon_cpu_path);
> > + cur_mon->mon_cpu_path = NULL;
> > + } else {
> > + cpu = CPU(obj);
> this potentially might abort if obj couldn't be cast to TYPE_CPU
>
This is deliberate... is there a case where cur_mon->mon_cpu_path would
legitimately point to something that isn't of type TYPE_CPU ?
>
> > + }
> > + }
> > + if (!cur_mon->mon_cpu_path) {
> > if (!first_cpu) {
> > return NULL;
> > }
> > monitor_set_cpu(first_cpu->cpu_index);
> > + cpu = first_cpu;
> > }
> > - cpu_synchronize_state(cur_mon->mon_cpu);
> > - return cur_mon->mon_cpu;
> > + cpu_synchronize_state(cpu);
> > + return cpu;
> > }
> >
> > CPUArchState *mon_get_cpu_env(void)
> >
> >
>
