Am 05.08.2020 um 09:19 hat Markus Armbruster geschrieben:
> Kevin Wolf <kw...@redhat.com> writes:
>
> > Am 04.08.2020 um 14:46 hat Markus Armbruster geschrieben:
> >> > diff --git a/monitor/hmp.c b/monitor/hmp.c
> >> > index d598dd02bb..f609fcf75b 100644
> >> > --- a/monitor/hmp.c
> >> > +++ b/monitor/hmp.c
> >> > @@ -1301,11 +1301,11 @@ cleanup:
> >> > static void monitor_read(void *opaque, const uint8_t *buf, int size)
> >> > {
> >> > MonitorHMP *mon;
> >> > - Monitor *old_mon = cur_mon;
> >> > + Monitor *old_mon = monitor_cur();
> >> > int i;
> >> >
> >> > - cur_mon = opaque;
> >> > - mon = container_of(cur_mon, MonitorHMP, common);
> >> > + monitor_set_cur(opaque);
> >> > + mon = container_of(monitor_cur(), MonitorHMP, common);
> >>
> >> Simpler:
> >>
> >> MonitorHMP *mon = container_of(opaque, MonitorHMP, common);
> >
> > opaque is void*, so it doesn't have a field 'common'.
>
> I actually compile-tested before I sent this. For once ;)
>
> Here's container_of():
>
> #define container_of(ptr, type, member) ({ \
> const typeof(((type *) 0)->member) *__mptr = (ptr); \
> (type *) ((char *) __mptr - offsetof(type, member));})
>
> Its first argument's only use is as an initializer for a pointer
> variable. Both type * and void * work fine there.
Ah, we just lose type checking.
That's what I get for replying from what I remember from over two months
ago. I was pretty sure I didn't like this way, but went with it because
the other way didn't work. Maybe I just assumed it didn't work, or tried
something different that actually fails. Who knows.
Kevin
