Update and rebase to QEMU 4.1

[pve-qemu.git] / debian / patches / extra / 0001-monitor-qmp-resume-monitor-when-clearing-its-queue.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Wolfgang Bumiller <w.bumiller@proxmox.com>
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 <w.bumiller@proxmox.com>
---
 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)