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monitor: Discard BLOCK_IO_ERROR event when VM rebooted

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Throttled event like QAPI_EVENT_BLOCK_IO_ERROR may be queued
to limit event rate. Event may be delivered when VM is rebooted
if the event was queued in the *monitor_qapi_event_state* hash table.
Which may casue VM pause and other related problems.
Such as seabios blocked during virtio-scsi initialization:
    vring_add_buf(vq, sg, out_num, in_num, 0, 0);
    vring_kick(vp, vq, 1);
    ------------> VM paused here <-----------
    /* Wait for reply */
    while (!vring_more_used(vq)) usleep(5);

Signed-off-by: Yan Wang <wangyan122@huawei.com>
Signed-off-by: imxcc <xingchaochao@huawei.com>
(cherry picked from commit 42aa18057deead287b570fc44caa8ed4f897c878)
This commit is contained in:
Chen Qun 2022-02-10 11:18:13 +08:00 committed by yezengruan
parent 6872e99bab
commit 28ad1a9fd2
1 changed files with 97 additions and 0 deletions
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97
monitor-Discard-BLOCK_IO_ERROR-event-when-VM-reboote.patch Normal file
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@ -0,0 +1,97 @@
From f5af9ac3c9af4602812060759f6f95da8725314b Mon Sep 17 00:00:00 2001
From: Yan Wang <wangyan122@huawei.com>
Date: Thu, 10 Feb 2022 11:18:13 +0800
Subject: [PATCH] monitor: Discard BLOCK_IO_ERROR event when VM rebooted
Throttled event like QAPI_EVENT_BLOCK_IO_ERROR may be queued
to limit event rate. Event may be delivered when VM is rebooted
if the event was queued in the *monitor_qapi_event_state* hash table.
Which may casue VM pause and other related problems.
Such as seabios blocked during virtio-scsi initialization:
vring_add_buf(vq, sg, out_num, in_num, 0, 0);
vring_kick(vp, vq, 1);
------------> VM paused here <-----------
/* Wait for reply */
while (!vring_more_used(vq)) usleep(5);
Signed-off-by: Yan Wang <wangyan122@huawei.com>
---
include/monitor/monitor.h | 2 ++
monitor/monitor.c | 30 ++++++++++++++++++++++++++++++
softmmu/runstate.c | 1 +
3 files changed, 33 insertions(+)
diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
index 12d395d62d..847445f972 100644
--- a/include/monitor/monitor.h
+++ b/include/monitor/monitor.h
@@ -56,4 +56,6 @@ void monitor_register_hmp(const char *name, bool info,
void monitor_register_hmp_info_hrt(const char *name,
HumanReadableText *(*handler)(Error **errp));
+void monitor_qapi_event_discard_io_error(void);
+
#endif /* MONITOR_H */
diff --git a/monitor/monitor.c b/monitor/monitor.c
index 013c628695..fb4ae9531c 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -34,6 +34,9 @@
#include "qemu/option.h"
#include "sysemu/qtest.h"
#include "trace.h"
+#include "qemu/log.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi/qmp/qobject.h"
/*
* To prevent flooding clients, events can be throttled. The
@@ -767,6 +770,33 @@ int monitor_init_opts(QemuOpts *opts, Error **errp)
return ret;
}
+void monitor_qapi_event_discard_io_error(void)
+{
+ GHashTableIter event_iter;
+ MonitorQAPIEventState *evstate;
+ gpointer key, value;
+ GString *json;
+
+ qemu_mutex_lock(&monitor_lock);
+ g_hash_table_iter_init(&event_iter, monitor_qapi_event_state);
+ while (g_hash_table_iter_next(&event_iter, &key, &value)) {
+ evstate = key;
+ /* Only QAPI_EVENT_BLOCK_IO_ERROR is discarded */
+ if (evstate->event == QAPI_EVENT_BLOCK_IO_ERROR) {
+ g_hash_table_iter_remove(&event_iter);
+ json = qobject_to_json(QOBJECT(evstate->qdict));
+ qemu_log(" %s event discarded\n", json->str);
+ timer_del(evstate->timer);
+ timer_free(evstate->timer);
+ qobject_unref(evstate->data);
+ qobject_unref(evstate->qdict);
+ g_string_free(json, true);
+ g_free(evstate);
+ }
+ }
+ qemu_mutex_unlock(&monitor_lock);
+}
+
QemuOptsList qemu_mon_opts = {
.name = "mon",
.implied_opt_name = "chardev",
diff --git a/softmmu/runstate.c b/softmmu/runstate.c
index 10d9b7365a..5736d908db 100644
--- a/softmmu/runstate.c
+++ b/softmmu/runstate.c
@@ -448,6 +448,7 @@ void qemu_system_reset(ShutdownCause reason)
qapi_event_send_reset(shutdown_caused_by_guest(reason), reason);
}
cpu_synchronize_all_post_reset();
+ monitor_qapi_event_discard_io_error();
}
/*
--
2.27.0