Re: [Qemu-devel] [PATCH v4 6/7] monitor: remove "x-oob", turn oob on by default

[Peter Xu <peterx@redhat.com>]

On Tue, Jun 19, 2018 at 04:16:49PM +0200, Markus Armbruster wrote:
> Peter Xu <peterx@redhat.com> writes:
> 
> > There was a regression reported by Eric Auger before with OOB:
> >
> >   http://lists.gnu.org/archive/html/qemu-devel/2018-03/msg06231.html
> >
> > It is fixed in 951702f39c ("monitor: bind dispatch bh to iohandler
> > context", 2018-04-10).
> >
> > For the bug, we turned Out-Of-Band feature of monitors off for 2.12
> > release.  Now we turn that on again after the 2.12 release.
> 
> Relating what happened in the order it happened could be easier to
> understand.  Perhaps:
> 
>   OOB commands were introduced in commit cf869d53172.  Unfortunately, we
>   ran into a regression, and had to disable them by default for 2.12
>   (commit be933ffc23).
> 
>   The regression has since been fixed (commit 951702f39c7 "monitor: bind
>   dispatch bh to iohandler context").  Time to re-enable OOB.

This indeed looks much nicer.

> 
> > This patch partly reverts be933ffc23 (monitor: new parameter "x-oob"),
> > meanwhile turn it on again by default for non-MUX QMPs.  Note that we
> 
> "by default"?

Did I mis-spell somewhere?

> 
> > can't enable Out-Of-Band for monitors with MUX-typed chardev backends,
> > because not all the chardev frontends can run without main thread, or
> > can run in multiple threads.
> >
> > Some trivial touch-up in the test code is required to make sure qmp-test
> > won't broke.
> 
> "won't break"

This one I did.

> 
> >
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  include/monitor/monitor.h |  1 -
> >  monitor.c                 | 17 +----------------
> >  tests/libqtest.c          |  2 +-
> >  tests/qmp-test.c          |  2 +-
> >  vl.c                      |  5 -----
> >  5 files changed, 3 insertions(+), 24 deletions(-)
> >
> > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> > index d6ab70cae2..0cb0538a31 100644
> > --- a/include/monitor/monitor.h
> > +++ b/include/monitor/monitor.h
> > @@ -13,7 +13,6 @@ extern Monitor *cur_mon;
> >  #define MONITOR_USE_READLINE  0x02
> >  #define MONITOR_USE_CONTROL   0x04
> >  #define MONITOR_USE_PRETTY    0x08
> > -#define MONITOR_USE_OOB       0x10
> >  
> >  bool monitor_cur_is_qmp(void);
> >  
> > diff --git a/monitor.c b/monitor.c
> > index c9a02ee40c..7fbcf84b02 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -4587,19 +4587,7 @@ void monitor_init(Chardev *chr, int flags)
> >  {
> >      Monitor *mon = g_malloc(sizeof(*mon));
> >      bool use_readline = flags & MONITOR_USE_READLINE;
> > -    bool use_oob = flags & MONITOR_USE_OOB;
> > -
> > -    if (use_oob) {
> > -        if (CHARDEV_IS_MUX(chr)) {
> > -            error_report("Monitor Out-Of-Band is not supported with "
> > -                         "MUX typed chardev backend");
> > -            exit(1);
> > -        }
> > -        if (use_readline) {
> > -            error_report("Monitor Out-Of-band is only supported by QMP");
> > -            exit(1);
> > -        }
> > -    }
> > +    bool use_oob = (flags & MONITOR_USE_CONTROL) && !CHARDEV_IS_MUX(chr);
> 
> A comment explaining (briefly!) why MUX prevents oob would be useful
> here.  Fortunately, you can simply steal from your commit message.

Done.

> 
> >  
> >      monitor_data_init(mon, false, use_oob);
> >  
> > @@ -4701,9 +4689,6 @@ QemuOptsList qemu_mon_opts = {
> >          },{
> >              .name = "pretty",
> >              .type = QEMU_OPT_BOOL,
> > -        },{
> > -            .name = "x-oob",
> > -            .type = QEMU_OPT_BOOL,
> >          },
> >          { /* end of list */ }
> >      },
> > diff --git a/tests/libqtest.c b/tests/libqtest.c
> > index 098af6aec4..c5cb3f925c 100644
> > --- a/tests/libqtest.c
> > +++ b/tests/libqtest.c
> > @@ -213,7 +213,7 @@ QTestState *qtest_init_without_qmp_handshake(bool use_oob,
> >                                    "-display none "
> >                                    "%s", qemu_binary, socket_path,
> >                                    getenv("QTEST_LOG") ? "/dev/fd/2" : "/dev/null",
> > -                                  qmp_socket_path, use_oob ? ",x-oob=on" : "",
> > +                                  qmp_socket_path, "",
> >                                    extra_args ?: "");
> >          execlp("/bin/sh", "sh", "-c", command, NULL);
> >          exit(1);
> > diff --git a/tests/qmp-test.c b/tests/qmp-test.c
> > index a49cbc6fde..3747bf7fbb 100644
> > --- a/tests/qmp-test.c
> > +++ b/tests/qmp-test.c
> > @@ -89,7 +89,7 @@ static void test_qmp_protocol(void)
> >      g_assert(q);
> >      test_version(qdict_get(q, "version"));
> >      capabilities = qdict_get_qlist(q, "capabilities");
> > -    g_assert(capabilities && qlist_empty(capabilities));
> > +    g_assert(capabilities);
> >      qobject_unref(resp);
> >  
> >      /* Test valid command before handshake */
> > diff --git a/vl.c b/vl.c
> > index 6e34fb348d..26a0bb3f0f 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -2307,11 +2307,6 @@ static int mon_init_func(void *opaque, QemuOpts *opts, Error **errp)
> >      if (qemu_opt_get_bool(opts, "pretty", 0))
> >          flags |= MONITOR_USE_PRETTY;
> >  
> > -    /* OOB is off by default */
> > -    if (qemu_opt_get_bool(opts, "x-oob", 0)) {
> > -        flags |= MONITOR_USE_OOB;
> > -    }
> > -
> >      chardev = qemu_opt_get(opts, "chardev");
> >      chr = qemu_chr_find(chardev);
> >      if (chr == NULL) {
> 
> Preferrably with the commit message touched up, and a common on MUX:
> Reviewed-by: Markus Armbruster <armbru@redhat.com>

Picked.

Thanks,

-- 
Peter Xu