[PATCH 2/3] migration: implement query migration threadinfo by name

[Jiang Jiacheng]

Introduce interface query-migrationthreads. The interface is use
with the migration thread name reported by qemu and returns with
migration thread name and its pid.
Introduce threadinfo.c to manage threads with migration.

Signed-off-by: Jiang Jiacheng <jiangjiacheng@huawei.com>
---
 migration/meson.build  |  1 +
 migration/threadinfo.c | 70 ++++++++++++++++++++++++++++++++++++++++++
 migration/threadinfo.h | 30 ++++++++++++++++++
 qapi/migration.json    | 30 ++++++++++++++++++
 4 files changed, 131 insertions(+)
 create mode 100644 migration/threadinfo.c
 create mode 100644 migration/threadinfo.h

diff --git a/migration/meson.build b/migration/meson.build
index 690487cf1a..ed7d27f11a 100644
--- a/migration/meson.build
+++ b/migration/meson.build
@@ -25,6 +25,7 @@ softmmu_ss.add(files(
   'savevm.c',
   'socket.c',
   'tls.c',
+  'threadinfo.c',
 ), gnutls)
 
 softmmu_ss.add(when: rdma, if_true: files('rdma.c'))
diff --git a/migration/threadinfo.c b/migration/threadinfo.c
new file mode 100644
index 0000000000..0df668d427
--- /dev/null
+++ b/migration/threadinfo.c
@@ -0,0 +1,70 @@
+/*
+ *  Migration Threads info
+ *
+ *  Copyright (c) 2022 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ *  Authors:
+ *  Jiang Jiacheng <jiangjiacheng@huawei.com>
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2 or later.
+ *  See the COPYING file in the top-level directory.
+ */
+
+#include "threadinfo.h"
+
+static QLIST_HEAD(, MigrationThread) migration_threads;
+
+MigrationThread* MigrationThreadAdd(const char *name, int thread_id)
+{
+    MigrationThread *thread = NULL;
+
+    thread = g_new0(MigrationThread, 1);
+    thread->name = (char*)name;
+    thread->thread_id = thread_id;
+
+    QLIST_INSERT_HEAD(&migration_threads, thread, node);
+
+    return thread;
+}
+
+void MigrationThreadDel(MigrationThread* thread)
+{
+    if (thread) {
+        QLIST_REMOVE(thread, node);
+           g_free(thread);
+    }
+}
+
+MigrationThread* MigrationThreadQuery(const char* name)
+{
+    MigrationThread *thread = NULL;
+
+    QLIST_FOREACH(thread, &migration_threads, node) {
+        if (!strcmp(thread->name, name)) {
+            return thread;
+        }
+    }
+
+    return NULL;
+}
+
+MigrationThreadInfo* qmp_query_migrationthreads(const char* name, Error **errp)
+{
+    MigrationThread *thread = NULL;
+    MigrationThreadInfo *info = NULL;
+
+    thread = MigrationThreadQuery(name);
+    if (!thread) {
+        goto err;
+    }
+
+    info = g_new0(MigrationThreadInfo, 1);
+    info->name = g_strdup(thread->name);
+    info->thread_id = thread->thread_id;
+
+    return info;
+
+err:
+    error_setg(errp, "thread '%s' doesn't exist", name);
+    return NULL;
+}
diff --git a/migration/threadinfo.h b/migration/threadinfo.h
new file mode 100644
index 0000000000..f62a6ff261
--- /dev/null
+++ b/migration/threadinfo.h
@@ -0,0 +1,30 @@
+/*
+ *  Migration Threads info
+ *
+ *  Copyright (c) 2022 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ *  Authors:
+ *  Jiang Jiacheng <jiangjiacheng@huawei.com>
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2 or later.
+ *  See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/queue.h"
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-migration.h"
+
+typedef struct MigrationThread MigrationThread;
+
+struct MigrationThread {
+    char *name; /* the name of migration thread */
+    int thread_id; /* ID of the underlying host thread */
+    QLIST_ENTRY(MigrationThread) node;
+};
+
+MigrationThread *MigrationThreadAdd(const char *name, int thread_id);
+
+void MigrationThreadDel(MigrationThread* info);
+
+MigrationThread* MigrationThreadQuery(const char* name);
diff --git a/qapi/migration.json b/qapi/migration.json
index b0cf366ac0..e93c3e560a 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1970,6 +1970,36 @@
 { 'command': 'query-vcpu-dirty-limit',
   'returns': [ 'DirtyLimitInfo' ] }
 
+##
+# @MigrationThreadInfo:
+#
+# Information about migrationthreads
+#
+# @name: the name of migration thread
+#
+# @thread-id: ID of the underlying host thread
+#
+# Since: 7.2
+##
+{ 'struct': 'MigrationThreadInfo',
+  'data': {'name': 'str',
+           'thread-id': 'int'} }
+
+##
+# @query-migrationthreads:
+#
+# Returns threadInfo about the thread specified by name
+#
+# data: migration thread name
+#
+# returns: information about the specified thread
+#
+# Since: 7.2
+##
+{ 'command': 'query-migrationthreads',
+  'data': { 'name': 'str' },
+  'returns': 'MigrationThreadInfo' }
+
 ##
 # @snapshot-save:
 #
-- 
2.33.0