From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Wolfgang Bumiller Date: Wed, 2 Oct 2019 10:30:03 +0200 Subject: [PATCH] monitor/qmp: resume monitor when clearing its queue When a monitor's queue is filled up in handle_qmp_command() it gets suspended. It's the dispatcher bh's job currently to resume the monitor, which it does after processing an event from the queue. However, it is possible for a CHR_EVENT_CLOSED event to be processed before before the bh is scheduled, which will clear the queue without resuming the monitor, thereby preventing the dispatcher from reaching the resume() call. Fix this by resuming the monitor when clearing a queue which was filled up. Signed-off-by: Wolfgang Bumiller --- monitor/qmp.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/monitor/qmp.c b/monitor/qmp.c index e1b196217d..fb3e66c62a 100644 --- a/monitor/qmp.c +++ b/monitor/qmp.c @@ -70,9 +70,19 @@ static void qmp_request_free(QMPRequest *req) /* Caller must hold mon->qmp.qmp_queue_lock */ static void monitor_qmp_cleanup_req_queue_locked(MonitorQMP *mon) { + bool need_resume = (!qmp_oob_enabled(mon) && mon->qmp_requests->length > 0) + || mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX; while (!g_queue_is_empty(mon->qmp_requests)) { qmp_request_free(g_queue_pop_head(mon->qmp_requests)); } + if (need_resume) { + /* + * Pairs with the monitor_suspend() in handle_qmp_command() in case the + * queue gets cleared from a CH_EVENT_CLOSED event before the dispatch + * bh got scheduled. + */ + monitor_resume(&mon->common); + } } static void monitor_qmp_cleanup_queues(MonitorQMP *mon)