On Fri, Jun 07, 2013 at 09:50:39AM -0400, Luiz Capitulino wrote:
> On Tue, 4 Jun 2013 16:35:09 -0500
> Michael Roth <mdr...@linux.vnet.ibm.com> wrote:
>
> > When CHR_EVENT_OPENED was initially added, it was CHR_EVENT_RESET,
> > and it was issued as a bottom-half:
> >
> > 86e94dea5b740dad65446c857f6959eae43e0ba6
> >
> > Which we basically used to print out a greeting/prompt for the
> > monitor.
> >
> > AFAICT the only reason this was ever done in a BH was because in
> > some cases we'd modify the chr_write handler for a new chardev
> > backend *after* the site where we issued the reset (see:
> > 86e94d:qemu_chr_open_stdio())
> >
> > At some point this event was renamed to CHR_EVENT_OPENED, and we've
> > maintained the use of this BH ever since.
> >
> > However, due to 9f939df955a4152aad69a19a77e0898631bb2c18, we schedule
> > the BH via g_idle_add(), which is causing events to sometimes be
> > delivered after we've already begun processing data from backends,
> > leading to:
> >
> > known bugs:
> >
> > QMP:
> > session negotation resets with OPENED event, in some cases this
> > is causing new sessions to get sporadically reset
> >
> > potential bugs:
> >
> > hw/usb/redirect.c:
> > can_read handler checks for dev->parser != NULL, which may be
> > true if CLOSED BH has not been executed yet. In the past, OPENED
> > quiesced outstanding CLOSED events prior to us reading client
> > data. If it's delayed, our check may allow reads to occur even
> > though we haven't processed the OPENED event yet, and when we
> > do finally get the OPENED event, our state may get reset.
> >
> > qtest.c:
> > can begin session before OPENED event is processed, leading to
> > a spurious reset of the system and irq_levels
> >
> > gdbstub.c:
> > may start a gdb session prior to the machine being paused
> >
> > To fix these, let's just drop the BH.
> >
> > Since the initial reasoning for using it still applies to an extent,
> > work around that by deferring the delivery of CHR_EVENT_OPENED until
> > after the chardevs have been fully initialized, toward the end of
> > qmp_chardev_add() (or some cases, qemu_chr_new_from_opts()). This
> > defers delivery long enough that we can be assured a CharDriverState
> > is fully initialized before CHR_EVENT_OPENED is sent.
> >
> > Also, rather than requiring each chardev to do an explicit open, do it
> > automatically, and allow the small few who don't desire such behavior to
> > suppress the OPENED-on-init behavior by setting a 'explicit_be_open'
> > flag.
> >
> > We additionally add missing OPENED events for stdio backends on w32,
> > which were previously not being issued, causing us to not recieve the
> > banner and initial prompts for qmp/hmp.
> >
> > Reported-by: Stefan Priebe <s.pri...@profihost.ag>
> > Cc: qemu-sta...@nongnu.org
> > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
>
> I don't know if the QMP queue is the ideal queue for this patch, but
> I'd happily apply it if I get at least one Reviewed-by from the CC'ed
> people.
Anthony actually added his Reviewed-by for v3, but I forgot to roll it
in the commit. If you do take it in through your tree can you add that?
Thanks!
>
>
> > ---
> > v3->v4:
> > * renamed 'suppress_be_open_on_init' to 'explicit_be_open' to match
> > existing 'explicit_fe_open' flag (Hans)
> > * added missing 'explicit_be_open' flags for spice vmc/port and
> > msmouse backends
> >
> > v2->v3:
> > * removed artifact in from v1 in backends/baum.c, test build with
> > BRLAPI=y (Anthony)
> > * rebased on latest origin/master
> >
> > v1->v2:
> > * default to sending OPENED on backend init, add flag to suppress
> > it (Anthony)
> > * fix missing OPENED for stdio backends on w32
> > * fix missing OPENED when qemu_chr_new_from_opts() doesn't use
> > qmp_chardev_add()
> > * clean up/update commit message
> >
> > backends/baum.c | 2 --
> > backends/msmouse.c | 1 +
> > include/sysemu/char.h | 2 +-
> > qemu-char.c | 38 +++++++++++++++++---------------------
> > spice-qemu-char.c | 1 +
> > ui/console.c | 1 -
> > ui/gtk.c | 1 -
> > 7 files changed, 20 insertions(+), 26 deletions(-)
> >
> > diff --git a/backends/baum.c b/backends/baum.c
> > index 4cba79f..62aa784 100644
> > --- a/backends/baum.c
> > +++ b/backends/baum.c
> > @@ -611,8 +611,6 @@ CharDriverState *chr_baum_init(void)
> >
> > qemu_set_fd_handler(baum->brlapi_fd, baum_chr_read, NULL, baum);
> >
> > - qemu_chr_be_generic_open(chr);
> > -
> > return chr;
> >
> > fail:
> > diff --git a/backends/msmouse.c b/backends/msmouse.c
> > index 0ac05a0..c0dbfcd 100644
> > --- a/backends/msmouse.c
> > +++ b/backends/msmouse.c
> > @@ -70,6 +70,7 @@ CharDriverState *qemu_chr_open_msmouse(void)
> > chr = g_malloc0(sizeof(CharDriverState));
> > chr->chr_write = msmouse_chr_write;
> > chr->chr_close = msmouse_chr_close;
> > + chr->explicit_be_open = true;
> >
> > qemu_add_mouse_event_handler(msmouse_event, chr, 0, "QEMU Microsoft
> > Mouse");
> >
> > diff --git a/include/sysemu/char.h b/include/sysemu/char.h
> > index 5e42c90..066c216 100644
> > --- a/include/sysemu/char.h
> > +++ b/include/sysemu/char.h
> > @@ -70,12 +70,12 @@ struct CharDriverState {
> > void (*chr_set_echo)(struct CharDriverState *chr, bool echo);
> > void (*chr_set_fe_open)(struct CharDriverState *chr, int fe_open);
> > void *opaque;
> > - int idle_tag;
> > char *label;
> > char *filename;
> > int be_open;
> > int fe_open;
> > int explicit_fe_open;
> > + int explicit_be_open;
> > int avail_connections;
> > QemuOpts *opts;
> > QTAILQ_ENTRY(CharDriverState) next;
> > diff --git a/qemu-char.c b/qemu-char.c
> > index d04b429..0b6ae95 100644
> > --- a/qemu-char.c
> > +++ b/qemu-char.c
> > @@ -110,19 +110,9 @@ void qemu_chr_be_event(CharDriverState *s, int event)
> > s->chr_event(s->handler_opaque, event);
> > }
> >
> > -static gboolean qemu_chr_be_generic_open_bh(gpointer opaque)
> > -{
> > - CharDriverState *s = opaque;
> > - qemu_chr_be_event(s, CHR_EVENT_OPENED);
> > - s->idle_tag = 0;
> > - return FALSE;
> > -}
> > -
> > void qemu_chr_be_generic_open(CharDriverState *s)
> > {
> > - if (s->idle_tag == 0) {
> > - s->idle_tag = g_idle_add(qemu_chr_be_generic_open_bh, s);
> > - }
> > + qemu_chr_be_event(s, CHR_EVENT_OPENED);
> > }
> >
> > int qemu_chr_fe_write(CharDriverState *s, const uint8_t *buf, int len)
> > @@ -247,6 +237,7 @@ static CharDriverState *qemu_chr_open_null(void)
> >
> > chr = g_malloc0(sizeof(CharDriverState));
> > chr->chr_write = null_chr_write;
> > + chr->explicit_be_open = true;
> > return chr;
> > }
> >
> > @@ -504,9 +495,6 @@ static CharDriverState
> > *qemu_chr_open_mux(CharDriverState *drv)
> > /* Frontend guest-open / -close notification is not support with muxes
> > */
> > chr->chr_set_fe_open = NULL;
> >
> > - /* Muxes are always open on creation */
> > - qemu_chr_be_generic_open(chr);
> > -
> > return chr;
> > }
> >
> > @@ -883,8 +871,6 @@ static CharDriverState *qemu_chr_open_fd(int fd_in, int
> > fd_out)
> > chr->chr_update_read_handler = fd_chr_update_read_handler;
> > chr->chr_close = fd_chr_close;
> >
> > - qemu_chr_be_generic_open(chr);
> > -
> > return chr;
> > }
> >
> > @@ -1243,6 +1229,7 @@ static CharDriverState *qemu_chr_open_pty(const char
> > *id,
> > chr->chr_update_read_handler = pty_chr_update_read_handler;
> > chr->chr_close = pty_chr_close;
> > chr->chr_add_watch = pty_chr_add_watch;
> > + chr->explicit_be_open = true;
> >
> > s->fd = io_channel_from_fd(master_fd);
> > s->timer_tag = 0;
> > @@ -1595,8 +1582,6 @@ static CharDriverState *qemu_chr_open_pp_fd(int fd)
> > chr->chr_close = pp_close;
> > chr->opaque = drv;
> >
> > - qemu_chr_be_generic_open(chr);
> > -
> > return chr;
> > }
> > #endif /* __linux__ */
> > @@ -1650,6 +1635,7 @@ static CharDriverState *qemu_chr_open_pp_fd(int fd)
> > chr->opaque = (void *)(intptr_t)fd;
> > chr->chr_write = null_chr_write;
> > chr->chr_ioctl = pp_ioctl;
> > + chr->explicit_be_open = true;
> > return chr;
> > }
> > #endif
> > @@ -1880,7 +1866,6 @@ static CharDriverState *qemu_chr_open_win_path(const
> > char *filename)
> > g_free(chr);
> > return NULL;
> > }
> > - qemu_chr_be_generic_open(chr);
> > return chr;
> > }
> >
> > @@ -1980,7 +1965,6 @@ static CharDriverState
> > *qemu_chr_open_pipe(ChardevHostdev *opts)
> > g_free(chr);
> > return NULL;
> > }
> > - qemu_chr_be_generic_open(chr);
> > return chr;
> > }
> >
> > @@ -1994,7 +1978,6 @@ static CharDriverState *qemu_chr_open_win_file(HANDLE
> > fd_out)
> > s->hcom = fd_out;
> > chr->opaque = s;
> > chr->chr_write = win_chr_write;
> > - qemu_chr_be_generic_open(chr);
> > return chr;
> > }
> >
> > @@ -2329,6 +2312,8 @@ static CharDriverState *qemu_chr_open_udp_fd(int fd)
> > chr->chr_write = udp_chr_write;
> > chr->chr_update_read_handler = udp_chr_update_read_handler;
> > chr->chr_close = udp_chr_close;
> > + /* be isn't opened until we get a connection */
> > + chr->explicit_be_open = true;
> > return chr;
> > }
> >
> > @@ -2731,6 +2716,8 @@ static CharDriverState *qemu_chr_open_socket_fd(int
> > fd, bool do_nodelay,
> > chr->get_msgfd = tcp_get_msgfd;
> > chr->chr_add_client = tcp_chr_add_client;
> > chr->chr_add_watch = tcp_chr_add_watch;
> > + /* be isn't opened until we get a connection */
> > + chr->explicit_be_open = true;
> >
> > if (is_listen) {
> > s->listen_fd = fd;
> > @@ -3325,6 +3312,12 @@ CharDriverState *qemu_chr_new_from_opts(QemuOpts
> > *opts,
> > if (!chr->filename)
> > chr->filename = g_strdup(qemu_opt_get(opts, "backend"));
> > chr->init = init;
> > + /* if we didn't create the chardev via qmp_chardev_add, we
> > + * need to send the OPENED event here
> > + */
> > + if (!chr->explicit_be_open) {
> > + qemu_chr_be_event(chr, CHR_EVENT_OPENED);
> > + }
> > QTAILQ_INSERT_TAIL(&chardevs, chr, next);
> >
> > if (qemu_opt_get_bool(opts, "mux", 0)) {
> > @@ -3804,6 +3797,9 @@ ChardevReturn *qmp_chardev_add(const char *id,
> > ChardevBackend *backend,
> > if (!chr->filename) {
> > chr->filename =
> > g_strdup(ChardevBackendKind_lookup[backend->kind]);
> > }
> > + if (!chr->explicit_be_open) {
> > + qemu_chr_be_event(chr, CHR_EVENT_OPENED);
> > + }
> > QTAILQ_INSERT_TAIL(&chardevs, chr, next);
> > return ret;
> > } else {
> > diff --git a/spice-qemu-char.c b/spice-qemu-char.c
> > index f10970c..6d147a7 100644
> > --- a/spice-qemu-char.c
> > +++ b/spice-qemu-char.c
> > @@ -255,6 +255,7 @@ static CharDriverState *chr_open(const char *subtype)
> > chr->chr_add_watch = spice_chr_add_watch;
> > chr->chr_close = spice_chr_close;
> > chr->chr_set_fe_open = spice_chr_set_fe_open;
> > + chr->explicit_be_open = true;
> >
> > QLIST_INSERT_HEAD(&spice_chars, s, next);
> >
> > diff --git a/ui/console.c b/ui/console.c
> > index b30853f..54b192d 100644
> > --- a/ui/console.c
> > +++ b/ui/console.c
> > @@ -1746,7 +1746,6 @@ static void text_console_do_init(CharDriverState
> > *chr, DisplayState *ds)
> > s->t_attrib = s->t_attrib_default;
> > }
> >
> > - qemu_chr_be_generic_open(chr);
> > if (chr->init)
> > chr->init(chr);
> > }
> > diff --git a/ui/gtk.c b/ui/gtk.c
> > index 3bc2842..ef1bb71 100644
> > --- a/ui/gtk.c
> > +++ b/ui/gtk.c
> > @@ -1216,7 +1216,6 @@ static GSList *gd_vc_init(GtkDisplayState *s,
> > VirtualConsole *vc, int index, GSL
> >
> > gtk_menu_shell_append(GTK_MENU_SHELL(view_menu), vc->menu_item);
> >
> > - qemu_chr_be_generic_open(vc->chr);
> > if (vc->chr->init) {
> > vc->chr->init(vc->chr);
> > }
>
