From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Wolfgang Bumiller Date: Wed, 2 Oct 2019 09:41:34 +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 even 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.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/monitor.c b/monitor.c index 4807bbe811..daadbcdede 100644 --- a/monitor.c +++ b/monitor.c @@ -356,12 +356,28 @@ static void qmp_request_free(QMPRequest *req) g_free(req); } +static bool qmp_oob_enabled(Monitor *mon) +{ + return mon->qmp.capab[QMP_CAPABILITY_OOB]; +} + /* Caller must hold mon->qmp.qmp_queue_lock */ static void monitor_qmp_cleanup_req_queue_locked(Monitor *mon) { + bool need_resume = + (!qmp_oob_enabled(mon) && mon->qmp.qmp_requests->length > 0) + || mon->qmp.qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX; while (!g_queue_is_empty(mon->qmp.qmp_requests)) { qmp_request_free(g_queue_pop_head(mon->qmp.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); + } } static void monitor_qmp_cleanup_queues(Monitor *mon) @@ -1157,11 +1173,6 @@ static void monitor_init_qmp_commands(void) qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG); } -static bool qmp_oob_enabled(Monitor *mon) -{ - return mon->qmp.capab[QMP_CAPABILITY_OOB]; -} - static void monitor_qmp_caps_reset(Monitor *mon) { memset(mon->qmp.capab_offered, 0, sizeof(mon->qmp.capab_offered));