Commit df152fb9 authored by Peter Xu's avatar Peter Xu Committed by Eric Blake
Browse files

monitor: let suspend_cnt be thread safe 



Monitor code now can be run in more than one thread.  Let it be thread
safe when accessing suspend_cnt counter.

Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <20180309090006.10018-13-peterx@redhat.com>
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent 546aa566

monitor.c

+8 −7
Original line number Diff line number Diff line
@@ -194,7 +194,7 @@ struct Monitor { 
    CharBackend chr;

    int reset_seen;

    int flags;

    int suspend_cnt;

    int suspend_cnt;            /* Needs to be accessed atomically */

    bool skip_flush;

    bool use_io_thr;
@@ -3819,7 +3819,7 @@ static int monitor_can_read(void *opaque) 
{

    Monitor *mon = opaque;



    return (mon->suspend_cnt == 0) ? 1 : 0;

    return !atomic_mb_read(&mon->suspend_cnt);

}



/*
@@ -3951,7 +3951,7 @@ int monitor_suspend(Monitor *mon) 
{

    if (!mon->rs)

        return -ENOTTY;

    mon->suspend_cnt++;

    atomic_inc(&mon->suspend_cnt);

    return 0;

}
@@ -3959,9 +3959,10 @@ void monitor_resume(Monitor *mon) 
{

    if (!mon->rs)

        return;

    if (--mon->suspend_cnt == 0)

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

        readline_show_prompt(mon->rs);

    }

}



static QObject *get_qmp_greeting(Monitor *mon)

{
@@ -4025,19 +4026,19 @@ static void monitor_event(void *opaque, int event) 
            monitor_resume(mon);

            monitor_flush(mon);

        } else {

            mon->suspend_cnt = 0;

            atomic_mb_set(&mon->suspend_cnt, 0);

        }

        break;



    case CHR_EVENT_MUX_OUT:

        if (mon->reset_seen) {

            if (mon->suspend_cnt == 0) {

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

                monitor_printf(mon, "\n");

            }

            monitor_flush(mon);

            monitor_suspend(mon);

        } else {

            mon->suspend_cnt++;

            atomic_inc(&mon->suspend_cnt);

        }

        qemu_mutex_lock(&mon->out_lock);

        mon->mux_out = 1;