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qemu-kvm/SOURCES/kvm-util-main-loop-Introduc...

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From b4969662de01848f887a3918e97e516efc213f71 Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Date: Mon, 25 Apr 2022 09:57:22 +0200
Subject: [PATCH 02/16] util/main-loop: Introduce the main loop into QOM
RH-Author: Nicolas Saenz Julienne <nsaenzju@redhat.com>
RH-MergeRequest: 93: util/thread-pool: Expose minimum and maximum size
RH-Commit: [2/3] a481b77e25ad50d13dcbe26b36c551b18c89bddd
RH-Bugzilla: 2031024
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
'event-loop-base' provides basic property handling for all 'AioContext'
based event loops. So let's define a new 'MainLoopClass' that inherits
from it. This will permit tweaking the main loop's properties through
qapi as well as through the command line using the '-object' keyword[1].
Only one instance of 'MainLoopClass' might be created at any time.
'EventLoopBaseClass' learns a new callback, 'can_be_deleted()' so as to
mark 'MainLoop' as non-deletable.
[1] For example:
-object main-loop,id=main-loop,aio-max-batch=<value>
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-3-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 70ac26b9e5ca8374bb3ef3f30b871726673c9f27)
---
event-loop-base.c | 13 ++++++++
include/qemu/main-loop.h | 10 ++++++
include/sysemu/event-loop-base.h | 1 +
meson.build | 3 +-
qapi/qom.json | 13 ++++++++
util/main-loop.c | 56 ++++++++++++++++++++++++++++++++
6 files changed, 95 insertions(+), 1 deletion(-)
diff --git a/event-loop-base.c b/event-loop-base.c
index a924c73a7c..e7f99a6ec8 100644
--- a/event-loop-base.c
+++ b/event-loop-base.c
@@ -73,10 +73,23 @@ static void event_loop_base_complete(UserCreatable *uc, Error **errp)
}
}
+static bool event_loop_base_can_be_deleted(UserCreatable *uc)
+{
+ EventLoopBaseClass *bc = EVENT_LOOP_BASE_GET_CLASS(uc);
+ EventLoopBase *backend = EVENT_LOOP_BASE(uc);
+
+ if (bc->can_be_deleted) {
+ return bc->can_be_deleted(backend);
+ }
+
+ return true;
+}
+
static void event_loop_base_class_init(ObjectClass *klass, void *class_data)
{
UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
ucc->complete = event_loop_base_complete;
+ ucc->can_be_deleted = event_loop_base_can_be_deleted;
object_class_property_add(klass, "aio-max-batch", "int",
event_loop_base_get_param,
diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index d3750c8e76..20c9387654 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -26,9 +26,19 @@
#define QEMU_MAIN_LOOP_H
#include "block/aio.h"
+#include "qom/object.h"
+#include "sysemu/event-loop-base.h"
#define SIG_IPI SIGUSR1
+#define TYPE_MAIN_LOOP "main-loop"
+OBJECT_DECLARE_TYPE(MainLoop, MainLoopClass, MAIN_LOOP)
+
+struct MainLoop {
+ EventLoopBase parent_obj;
+};
+typedef struct MainLoop MainLoop;
+
/**
* qemu_init_main_loop: Set up the process so that it can run the main loop.
*
diff --git a/include/sysemu/event-loop-base.h b/include/sysemu/event-loop-base.h
index 8e77d8b69f..fced4c9fea 100644
--- a/include/sysemu/event-loop-base.h
+++ b/include/sysemu/event-loop-base.h
@@ -25,6 +25,7 @@ struct EventLoopBaseClass {
void (*init)(EventLoopBase *base, Error **errp);
void (*update_params)(EventLoopBase *base, Error **errp);
+ bool (*can_be_deleted)(EventLoopBase *base);
};
struct EventLoopBase {
diff --git a/meson.build b/meson.build
index b9c919a55e..5a7c10e639 100644
--- a/meson.build
+++ b/meson.build
@@ -2832,7 +2832,8 @@ libqemuutil = static_library('qemuutil',
sources: util_ss.sources() + stub_ss.sources() + genh,
dependencies: [util_ss.dependencies(), libm, threads, glib, socket, malloc, pixman])
qemuutil = declare_dependency(link_with: libqemuutil,
- sources: genh + version_res)
+ sources: genh + version_res,
+ dependencies: [event_loop_base])
if have_system or have_user
decodetree = generator(find_program('scripts/decodetree.py'),
diff --git a/qapi/qom.json b/qapi/qom.json
index a2439533c5..7d4a2ac1b9 100644
--- a/qapi/qom.json
+++ b/qapi/qom.json
@@ -540,6 +540,17 @@
'*poll-grow': 'int',
'*poll-shrink': 'int' } }
+##
+# @MainLoopProperties:
+#
+# Properties for the main-loop object.
+#
+# Since: 7.1
+##
+{ 'struct': 'MainLoopProperties',
+ 'base': 'EventLoopBaseProperties',
+ 'data': {} }
+
##
# @MemoryBackendProperties:
#
@@ -830,6 +841,7 @@
{ 'name': 'input-linux',
'if': 'CONFIG_LINUX' },
'iothread',
+ 'main-loop',
{ 'name': 'memory-backend-epc',
'if': 'CONFIG_LINUX' },
'memory-backend-file',
@@ -895,6 +907,7 @@
'input-linux': { 'type': 'InputLinuxProperties',
'if': 'CONFIG_LINUX' },
'iothread': 'IothreadProperties',
+ 'main-loop': 'MainLoopProperties',
'memory-backend-epc': { 'type': 'MemoryBackendEpcProperties',
'if': 'CONFIG_LINUX' },
'memory-backend-file': 'MemoryBackendFileProperties',
diff --git a/util/main-loop.c b/util/main-loop.c
index b7b0ce4ca0..5b13f456fa 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -33,6 +33,7 @@
#include "qemu/error-report.h"
#include "qemu/queue.h"
#include "qemu/compiler.h"
+#include "qom/object.h"
#ifndef _WIN32
#include <sys/wait.h>
@@ -184,6 +185,61 @@ int qemu_init_main_loop(Error **errp)
return 0;
}
+static void main_loop_update_params(EventLoopBase *base, Error **errp)
+{
+ if (!qemu_aio_context) {
+ error_setg(errp, "qemu aio context not ready");
+ return;
+ }
+
+ aio_context_set_aio_params(qemu_aio_context, base->aio_max_batch, errp);
+}
+
+MainLoop *mloop;
+
+static void main_loop_init(EventLoopBase *base, Error **errp)
+{
+ MainLoop *m = MAIN_LOOP(base);
+
+ if (mloop) {
+ error_setg(errp, "only one main-loop instance allowed");
+ return;
+ }
+
+ main_loop_update_params(base, errp);
+
+ mloop = m;
+ return;
+}
+
+static bool main_loop_can_be_deleted(EventLoopBase *base)
+{
+ return false;
+}
+
+static void main_loop_class_init(ObjectClass *oc, void *class_data)
+{
+ EventLoopBaseClass *bc = EVENT_LOOP_BASE_CLASS(oc);
+
+ bc->init = main_loop_init;
+ bc->update_params = main_loop_update_params;
+ bc->can_be_deleted = main_loop_can_be_deleted;
+}
+
+static const TypeInfo main_loop_info = {
+ .name = TYPE_MAIN_LOOP,
+ .parent = TYPE_EVENT_LOOP_BASE,
+ .class_init = main_loop_class_init,
+ .instance_size = sizeof(MainLoop),
+};
+
+static void main_loop_register_types(void)
+{
+ type_register_static(&main_loop_info);
+}
+
+type_init(main_loop_register_types)
+
static int max_priority;
#ifndef _WIN32
--
2.31.1