Peter Xu <pet...@redhat.com> writes:
> On Thu, May 17, 2018 at 02:46:36PM +0200, Markus Armbruster wrote:
>> Peter Xu <pet...@redhat.com> writes:
>>
>> > Add some explicit comment for both Readline and cpu_set/cpu_get helpers
>> > that they do not need the mon_lock protection.
>>
>> Appreciated!
>>
>> > Signed-off-by: Peter Xu <pet...@redhat.com>
>> > ---
>> > monitor.c | 5 +++--
>> > 1 file changed, 3 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/monitor.c b/monitor.c
>> > index d6c3c08932..ae5bca9d7c 100644
>> > --- a/monitor.c
>> > +++ b/monitor.c
>> > @@ -207,7 +207,7 @@ struct Monitor {
>> > int suspend_cnt; /* Needs to be accessed atomically */
>> > bool skip_flush;
>> > bool use_io_thr;
>> > - ReadLineState *rs;
>> > + ReadLineState *rs; /* Only used in parser, so no lock needed. */
>>
>> Pardon the ignorant question: why does "only used in parser" imply "no
>> lock needed"?
>
> Since even if the monitors can be run in multiple threads now, the
> monitor parser of a specific Monitor will still only be run in either
> the main thread or the monitor iothread. My fault to be unclear on
> the comment. Maybe this one is better:
>
> It is only used in parser, and the parser of a monitor will only be
> run either in main thread or monitor IOThread but never both, so no
> lock is needed when accessing ReadLineState.
One further question, just to help me understand how this stuff works:
what are the conditions for the parser running in the main thread, and
what are the conditions for it running in the monitor IOThread?
[...]
