On Fri, Jan 12, 2018 at 03:48:10PM -0600, Eric Blake wrote:
> On 12/19/2017 02:45 AM, Peter Xu wrote:
> > Monitor code now can be run in more than one thread. Let it be thread
> > safe when accessing suspend_cnt counter.
> >
> > Signed-off-by: Peter Xu <pet...@redhat.com>
> > ---
> > monitor.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/monitor.c b/monitor.c
> > index cf1e5d881c..844508d134 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -3862,7 +3862,7 @@ static int monitor_can_read(void *opaque)
> > {
> > Monitor *mon = opaque;
> >
> > - return (mon->suspend_cnt == 0) ? 1 : 0;
> > + return (atomic_mb_read(&mon->suspend_cnt) == 0) ? 1 : 0;
>
> Worth a comment at the declaration of suspend_cnt that it must be
> accessed atomically?
Sure.
>
> I find anything that does '(boolexpr) ? 1 : 0' to be a pointless waste
> of typing. It is semantically equivalent and shorter to write either of:
>
> return atomic_mb_read(&mon->suspend_cnt) == 0;
> return !atomic_mb_read(&mon->suspend_cnt);
Sure, will use the latter.
>
> At any rate, I checked that all uses of suspend_cnt were converted over
> to atomic API, so this looks correct, whether or not you add my tweaks.
>
> Reviewed-by: Eric Blake <ebl...@redhat.com>
Thanks for reviewing.
--
Peter Xu
