Commit e3e977d4 authored by Peter Xu's avatar Peter Xu Committed by Eric Blake
Browse files

monitor: let suspend/resume work even with QMPs 



This patches allows QMP monitors to be suspended/resumed.

One thing to mention is that for QMPs that are using IOThreads, we need
an explicit kick for the IOThread in case it is sleeping.

Meanwhile, we need to take special care on non-interactive HMPs.
Currently only gdbserver is using that.  For these monitors, we still
don't allow suspend/resume operations.

Since at it, add traces for the operations.

Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <20180309090006.10018-14-peterx@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent df152fb9

monitor.c

+44 −3
Original line number Diff line number Diff line
@@ -250,6 +250,21 @@ static inline bool monitor_is_qmp(const Monitor *mon) 
    return (mon->flags & MONITOR_USE_CONTROL);

}



/**

 * Whether @mon is using readline?  Note: not all HMP monitors use

 * readline, e.g., gdbserver has a non-interactive HMP monitor, so

 * readline is not used there.

 */

static inline bool monitor_uses_readline(const Monitor *mon)

{

    return mon->flags & MONITOR_USE_READLINE;

}



static inline bool monitor_is_hmp_non_interactive(const Monitor *mon)

{

    return !monitor_is_qmp(mon) && !monitor_uses_readline(mon);

}



/**

 * Is the current monitor, if any, a QMP monitor?

 */
@@ -3949,20 +3964,46 @@ static void monitor_command_cb(void *opaque, const char *cmdline, 


int monitor_suspend(Monitor *mon)

{

    if (!mon->rs)

    if (monitor_is_hmp_non_interactive(mon)) {

        return -ENOTTY;

    }



    atomic_inc(&mon->suspend_cnt);



    if (monitor_is_qmp(mon)) {

        /*

         * Kick iothread to make sure this takes effect.  It'll be

         * evaluated again in prepare() of the watch object.

         */

        aio_notify(iothread_get_aio_context(mon_global.mon_iothread));

    }



    trace_monitor_suspend(mon, 1);

    return 0;

}



void monitor_resume(Monitor *mon)

{

    if (!mon->rs)

    if (monitor_is_hmp_non_interactive(mon)) {

        return;

    }



    if (atomic_dec_fetch(&mon->suspend_cnt) == 0) {

        if (monitor_is_qmp(mon)) {

            /*

             * For QMP monitors that are running in IOThread, let's

             * kick the thread in case it's sleeping.

             */

            if (mon->use_io_thr) {

                aio_notify(iothread_get_aio_context(mon_global.mon_iothread));

            }

        } else {

            assert(mon->rs);

            readline_show_prompt(mon->rs);

        }

    }

    trace_monitor_suspend(mon, -1);

}



static QObject *get_qmp_greeting(Monitor *mon)

{

trace-events

+1 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ monitor_protocol_event_emit(uint32_t event, void *data) "event=%d data=%p" 
monitor_protocol_event_queue(uint32_t event, void *qdict, uint64_t rate) "event=%d data=%p rate=%" PRId64

handle_hmp_command(void *mon, const char *cmdline) "mon %p cmdline: %s"

handle_qmp_command(void *mon, const char *req) "mon %p req: %s"

monitor_suspend(void *ptr, int cnt) "mon %p: %d"



# dma-helpers.c

dma_blk_io(void *dbs, void *bs, int64_t offset, bool to_dev) "dbs=%p bs=%p offset=%" PRId64 " to_dev=%d"