A chardev may stop trying to write if the associated can_read()
callback returned 0. This happens when the monitor is suspended.
The frontend is supposed to call qemu_chr_fe_accept_input() when it is
ready to accept data again.

An issue was observed with a spice port: pending commands may be
delayed, as the chardev is not flushed. Most chardev don't use the
accept_input() callback, and instead check regularly if they can
write. The ones that do use it are braille, mux, msmouse,
spice (abstract), spicevmc, spiceport, wctablet.

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Acked-by: Markus Armbruster <arm...@redhat.com>
---
 monitor.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/monitor.c b/monitor.c
index a1999e396c..33823b035a 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4407,6 +4407,7 @@ void monitor_resume(Monitor *mon)
             assert(mon->rs);
             readline_show_prompt(mon->rs);
         }
+        qemu_chr_fe_accept_input(&mon->chr);
     }
     trace_monitor_suspend(mon, -1);
 }
-- 
2.18.0.547.g1d89318c48


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