Hi On Thu, Apr 12, 2018 at 4:48 PM, Dr. David Alan Gilbert <dgilb...@redhat.com> wrote: > * Marc-André Lureau (marcandre.lur...@redhat.com) wrote: >> Make screendump asynchronous to provide correct screendumps. >> >> HMP doesn't have async support, so it has to remain synchronous and >> potentially incorrect to avoid potential races. >> >> Fixes: >> https://bugzilla.redhat.com/show_bug.cgi?id=1230527 >> >> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> > > Hi, > Looking at this and the previous pair of patches, I think we'd be > better if we defined that async commands took a callback function > pointer and data that they call. > > Here we've got 'graphic_hw_update_done' that explicitly walks qmp > lists; but I think it's better just to pass graphic_hw_update() the > completion data together with a callback function and it calls that when > it's done. > > (Also isn't it a little bit of a race, calling graphic_hw_update() and > *then* adding the entry to the list? Can't it end up calling the _done() > before we've added it to the list). > > Also, do we need a list of outstanding screendumps, or should we just > have a list of async commands. > > It wouldn't seem hard to use the async-QMP command from the HMP > and then just provide a way to tell whether it had finished. >
I should have updated the commit message, but the following patches do introduce async-QMP support for HMP (by suspending HMP monitor, just like QMP). > Dave > >> --- >> qapi/ui.json | 3 +- >> include/ui/console.h | 3 ++ >> hmp.c | 2 +- >> ui/console.c | 99 ++++++++++++++++++++++++++++++++++++++++---- >> 4 files changed, 96 insertions(+), 11 deletions(-) >> >> diff --git a/qapi/ui.json b/qapi/ui.json >> index 5d01ad4304..4d2c326fb9 100644 >> --- a/qapi/ui.json >> +++ b/qapi/ui.json >> @@ -96,7 +96,8 @@ >> # >> ## >> { 'command': 'screendump', >> - 'data': {'filename': 'str', '*device': 'str', '*head': 'int'} } >> + 'data': {'filename': 'str', '*device': 'str', '*head': 'int'}, >> + 'async': true } >> >> ## >> # == Spice >> diff --git a/include/ui/console.h b/include/ui/console.h >> index fc21621656..0c02190963 100644 >> --- a/include/ui/console.h >> +++ b/include/ui/console.h >> @@ -74,6 +74,9 @@ struct MouseTransformInfo { >> }; >> >> void hmp_mouse_set(Monitor *mon, const QDict *qdict); >> +void hmp_screendump_sync(const char *filename, >> + bool has_device, const char *device, >> + bool has_head, int64_t head, Error **errp); >> >> /* keysym is a unicode code except for special keys (see QEMU_KEY_xxx >> constants) */ >> diff --git a/hmp.c b/hmp.c >> index 679467d85a..da9008fe63 100644 >> --- a/hmp.c >> +++ b/hmp.c >> @@ -2144,7 +2144,7 @@ void hmp_screendump(Monitor *mon, const QDict *qdict) >> int64_t head = qdict_get_try_int(qdict, "head", 0); >> Error *err = NULL; >> >> - qmp_screendump(filename, id != NULL, id, id != NULL, head, &err); >> + hmp_screendump_sync(filename, id != NULL, id, id != NULL, head, &err); >> hmp_handle_error(mon, &err); >> } >> >> diff --git a/ui/console.c b/ui/console.c >> index 29234605a7..da51861191 100644 >> --- a/ui/console.c >> +++ b/ui/console.c >> @@ -32,6 +32,7 @@ >> #include "chardev/char-fe.h" >> #include "trace.h" >> #include "exec/memory.h" >> +#include "monitor/monitor.h" >> >> #define DEFAULT_BACKSCROLL 512 >> #define CONSOLE_CURSOR_PERIOD 500 >> @@ -116,6 +117,12 @@ typedef enum { >> TEXT_CONSOLE_FIXED_SIZE >> } console_type_t; >> >> +struct qmp_screendump { >> + gchar *filename; >> + QmpReturn *ret; >> + QLIST_ENTRY(qmp_screendump) link; >> +}; >> + >> struct QemuConsole { >> Object parent; >> >> @@ -165,6 +172,8 @@ struct QemuConsole { >> QEMUFIFO out_fifo; >> uint8_t out_fifo_buf[16]; >> QEMUTimer *kbd_timer; >> + >> + QLIST_HEAD(, qmp_screendump) qmp_screendumps; >> }; >> >> struct DisplayState { >> @@ -190,6 +199,8 @@ static void dpy_refresh(DisplayState *s); >> static DisplayState *get_alloc_displaystate(void); >> static void text_console_update_cursor_timer(void); >> static void text_console_update_cursor(void *opaque); >> +static void ppm_save(const char *filename, DisplaySurface *ds, >> + Error **errp); >> >> static void gui_update(void *opaque) >> { >> @@ -256,8 +267,42 @@ static void gui_setup_refresh(DisplayState *ds) >> ds->have_text = have_text; >> } >> >> +static void qmp_screendump_finish(QemuConsole *con, const char *filename, >> + QmpReturn *ret) >> +{ >> + Error *err = NULL; >> + DisplaySurface *surface; >> + Monitor *prev_mon = cur_mon; >> + >> + if (qmp_return_is_cancelled(ret)) { >> + return; >> + } >> + >> + cur_mon = qmp_return_get_monitor(ret); >> + surface = qemu_console_surface(con); >> + >> + /* FIXME: async save with coroutine? it would have to copy or lock >> + * the surface. */ >> + ppm_save(filename, surface, &err); >> + >> + if (err) { >> + qmp_return_error(ret, err); >> + } else { >> + qmp_screendump_return(ret); >> + } >> + cur_mon = prev_mon; >> +} >> + >> void graphic_hw_update_done(QemuConsole *con) >> { >> + struct qmp_screendump *dump, *next; >> + >> + QLIST_FOREACH_SAFE(dump, &con->qmp_screendumps, link, next) { >> + qmp_screendump_finish(con, dump->filename, dump->ret); >> + g_free(dump->filename); >> + QLIST_REMOVE(dump, link); >> + g_free(dump); >> + } >> } >> >> bool graphic_hw_update(QemuConsole *con) >> @@ -358,35 +403,70 @@ write_err: >> goto out; >> } >> >> -void qmp_screendump(const char *filename, bool has_device, const char >> *device, >> - bool has_head, int64_t head, Error **errp) >> + >> +static QemuConsole *get_console(bool has_device, const char *device, >> + bool has_head, int64_t head, Error **errp) >> { >> - QemuConsole *con; >> - DisplaySurface *surface; >> + QemuConsole *con = NULL; >> >> if (has_device) { >> con = qemu_console_lookup_by_device_name(device, has_head ? head : >> 0, >> errp); >> - if (!con) { >> - return; >> - } >> } else { >> if (has_head) { >> error_setg(errp, "'head' must be specified together with >> 'device'"); >> - return; >> + return NULL; >> } >> con = qemu_console_lookup_by_index(0); >> if (!con) { >> error_setg(errp, "There is no console to take a screendump >> from"); >> - return; >> } >> } >> >> + return con; >> +} >> + >> +void hmp_screendump_sync(const char *filename, >> + bool has_device, const char *device, >> + bool has_head, int64_t head, Error **errp) >> +{ >> + DisplaySurface *surface; >> + QemuConsole *con = get_console(has_device, device, has_head, head, >> errp); >> + >> + if (!con) { >> + return; >> + } >> + /* This may not complete the drawing with Spice, you may have >> + * glitches or outdated dumps, use qmp instead! */ >> graphic_hw_update(con); >> surface = qemu_console_surface(con); >> ppm_save(filename, surface, errp); >> } >> >> +void qmp_screendump(const char *filename, >> + bool has_device, const char *device, >> + bool has_head, int64_t head, >> + QmpReturn *qret) >> +{ >> + Error *err = NULL; >> + bool async; >> + QemuConsole *con = get_console(has_device, device, has_head, head, >> &err); >> + >> + if (!con) { >> + qmp_return_error(qret, err); >> + return; >> + } >> + async = graphic_hw_update(con); >> + if (async) { >> + struct qmp_screendump *dump = g_new(struct qmp_screendump, 1); >> + dump->filename = g_strdup(filename); >> + dump->ret = qret; >> + QLIST_INSERT_HEAD(&con->qmp_screendumps, dump, link); >> + } else { >> + qmp_screendump_finish(con, filename, qret); >> + } >> +} >> + >> void graphic_hw_text_update(QemuConsole *con, console_ch_t *chardata) >> { >> if (!con) { >> @@ -1280,6 +1360,7 @@ static QemuConsole *new_console(DisplayState *ds, >> console_type_t console_type, >> obj = object_new(TYPE_QEMU_CONSOLE); >> s = QEMU_CONSOLE(obj); >> s->head = head; >> + QLIST_INIT(&s->qmp_screendumps); >> object_property_add_link(obj, "device", TYPE_DEVICE, >> (Object **)&s->device, >> object_property_allow_set_link, >> -- >> 2.17.0.rc1.1.g4c4f2b46a3 >> > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK > -- Marc-André Lureau