[v3,01/38] HACK: add back OOB

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index efd77939af..4a0b33b373 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -754,6 +754,7 @@  static void *postcopy_ram_fault_thread(void *opaque)
         }
     }
     trace_postcopy_ram_fault_thread_exit();
+    g_free(pfd);
     return NULL;
 }
 
diff --git a/monitor.c b/monitor.c
index 77f4c41cfa..d57bbbb134 100644
--- a/monitor.c
+++ b/monitor.c
@@ -36,6 +36,7 @@ 
 #include "net/slirp.h"
 #include "chardev/char-fe.h"
 #include "chardev/char-io.h"
+#include "chardev/char-mux.h"
 #include "ui/qemu-spice.h"
 #include "sysemu/numa.h"
 #include "monitor/monitor.h"
@@ -3996,6 +3997,18 @@  static void monitor_qmp_respond(Monitor *mon, QObject *rsp,
             qdict_put_obj(qobject_to(QDict, rsp), "id", id);
         }
 
+        if (mon->qmp.commands == &qmp_cap_negotiation_commands) {
+            qdict = qdict_get_qdict(qobject_to(QDict, rsp), "error");
+            if (qdict
+                && !g_strcmp0(qdict_get_try_str(qdict, "class"),
+                          QapiErrorClass_str(ERROR_CLASS_COMMAND_NOT_FOUND))) {
+                /* Provide a more useful error message */
+                qdict_del(qdict, "desc");
+                qdict_put_str(qdict, "desc", "Expecting capabilities"
+                              " negotiation with 'qmp_capabilities'");
+            }
+        }
+
         monitor_json_emitter(mon, rsp);
     }
 
@@ -4027,7 +4040,6 @@  static void monitor_qmp_dispatch_one(QMPRequest *req_obj)
 {
     Monitor *mon, *old_mon;
     QObject *req, *rsp = NULL, *id;
-    QDict *qdict = NULL;
     bool need_resume;
 
     req = req_obj->req;
@@ -4050,18 +4062,6 @@  static void monitor_qmp_dispatch_one(QMPRequest *req_obj)
 
     cur_mon = old_mon;
 
-    if (mon->qmp.commands == &qmp_cap_negotiation_commands) {
-        qdict = qdict_get_qdict(qobject_to(QDict, rsp), "error");
-        if (qdict
-            && !g_strcmp0(qdict_get_try_str(qdict, "class"),
-                    QapiErrorClass_str(ERROR_CLASS_COMMAND_NOT_FOUND))) {
-            /* Provide a more useful error message */
-            qdict_del(qdict, "desc");
-            qdict_put_str(qdict, "desc", "Expecting capabilities negotiation"
-                          " with 'qmp_capabilities'");
-        }
-    }
-
     /* Respond if necessary */
     monitor_qmp_respond(mon, rsp, NULL, id);
 
@@ -4536,8 +4536,10 @@  static void monitor_qmp_setup_handlers_bh(void *opaque)
 void monitor_init(Chardev *chr, int flags)
 {
     Monitor *mon = g_malloc(sizeof(*mon));
+    /* Enable IOThread for QMPs that are not using MUX chardev backends. */
+    bool use_io_thr = (!CHARDEV_IS_MUX(chr)) && (flags & MONITOR_USE_CONTROL);
 
-    monitor_data_init(mon, false, false);
+    monitor_data_init(mon, false, use_io_thr);
 
     qemu_chr_fe_init(&mon->chr, chr, &error_abort);
     mon->flags = flags;
diff --git a/tests/qmp-test.c b/tests/qmp-test.c
index 558e83540c..07c0b87e27 100644
--- a/tests/qmp-test.c
+++ b/tests/qmp-test.c
@@ -80,6 +80,9 @@  static void test_qmp_protocol(void)
     QDict *resp, *q, *ret;
     QList *capabilities;
     QTestState *qts;
+    const QListEntry *entry;
+    QString *qstr;
+    int i;
 
     qts = qtest_init_without_qmp_handshake(common_args);
 
@@ -89,7 +92,13 @@  static void test_qmp_protocol(void)
     g_assert(q);
     test_version(qdict_get(q, "version"));
     capabilities = qdict_get_qlist(q, "capabilities");
-    g_assert(capabilities && qlist_empty(capabilities));
+    g_assert(capabilities);
+    entry = qlist_first(capabilities);
+    g_assert(entry);
+    qstr = qobject_to(QString, entry->value);
+    g_assert(qstr);
+    g_assert_cmpstr(qstring_get_str(qstr), ==, "oob");
+    QDECREF(resp);
 
     /* Test valid command before handshake */
     resp = qtest_qmp(qts, "{ 'execute': 'query-version' }");
@@ -131,9 +140,94 @@  static void test_qmp_protocol(void)
     g_assert_cmpint(qdict_get_int(resp, "id"), ==, 2);
     QDECREF(resp);
 
+    /*
+     * Test command batching.  In current test OOB is not enabled, we
+     * should be able to run as many commands in batch as we like.
+     * Using 16 (>8, which is OOB queue length) to make sure OOB won't
+     * break existing clients.  Note: this test does not control the
+     * scheduling of QEMU's QMP command processing threads so it may
+     * not really trigger batching inside QEMU.  This is just a
+     * best-effort test.
+     */
+    for (i = 0; i < 16; i++) {
+        qtest_async_qmp(qts, "{ 'execute': 'query-version' }");
+    }
+    /* Verify the replies to make sure no command is dropped. */
+    for (i = 0; i < 16; i++) {
+        resp = qtest_qmp_receive(qts);
+        /* It should never be dropped.  Each of them should be a reply. */
+        g_assert(qdict_haskey(resp, "return"));
+        g_assert(!qdict_haskey(resp, "event"));
+        QDECREF(resp);
+    }
+
     qtest_quit(qts);
 }
 
+/* Tests for Out-Of-Band support. */
+static void test_qmp_oob(void)
+{
+    QDict *resp;
+    int acks = 0;
+    const char *cmd_id;
+
+    global_qtest = qtest_init_without_qmp_handshake(common_args);
+
+    /* Ignore the greeting message. */
+    resp = qmp_receive();
+    g_assert(qdict_get_qdict(resp, "QMP"));
+    QDECREF(resp);
+
+    /* Try a fake capability, it should fail. */
+    resp = qmp("{ 'execute': 'qmp_capabilities', "
+               "  'arguments': { 'enable': [ 'cap-does-not-exist' ] } }");
+    g_assert(qdict_haskey(resp, "error"));
+    QDECREF(resp);
+
+    /* Now, enable OOB in current QMP session, it should succeed. */
+    resp = qmp("{ 'execute': 'qmp_capabilities', "
+               "  'arguments': { 'enable': [ 'oob' ] } }");
+    g_assert(qdict_haskey(resp, "return"));
+    QDECREF(resp);
+
+    /*
+     * Try any command that does not support OOB but with OOB flag. We
+     * should get failure.
+     */
+    resp = qmp("{ 'execute': 'query-cpus',"
+               "  'control': { 'run-oob': true } }");
+    g_assert(qdict_haskey(resp, "error"));
+    QDECREF(resp);
+
+    /*
+     * First send the "x-oob-test" command with lock=true and
+     * oob=false, it should hang the dispatcher and main thread;
+     * later, we send another lock=false with oob=true to continue
+     * that thread processing.  Finally we should receive replies from
+     * both commands.
+     */
+    qmp_async("{ 'execute': 'x-oob-test',"
+              "  'arguments': { 'lock': true }, "
+              "  'id': 'lock-cmd'}");
+    qmp_async("{ 'execute': 'x-oob-test', "
+              "  'arguments': { 'lock': false }, "
+              "  'control': { 'run-oob': true }, "
+              "  'id': 'unlock-cmd' }");
+
+    /* Ignore all events.  Wait for 2 acks */
+    while (acks < 2) {
+        resp = qmp_receive();
+        cmd_id = qdict_get_str(resp, "id");
+        if (!g_strcmp0(cmd_id, "lock-cmd") ||
+            !g_strcmp0(cmd_id, "unlock-cmd")) {
+            acks++;
+        }
+        QDECREF(resp);
+    }
+
+    qtest_end();
+}
+
 static int query_error_class(const char *cmd)
 {
     static struct {
@@ -318,6 +412,7 @@  int main(int argc, char *argv[])
     g_test_init(&argc, &argv, NULL);
 
     qtest_add_func("qmp/protocol", test_qmp_protocol);
+    qtest_add_func("qmp/oob", test_qmp_oob);
     qmp_schema_init(&schema);
     add_query_tests(&schema);
 
diff --git a/tests/Makefile.include b/tests/Makefile.include
index eb218a9539..0b277036df 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -669,13 +669,13 @@  tests/test-qapi-events.c tests/test-qapi-events.h \
 tests/test-qapi-introspect.c tests/test-qapi-introspect.h: \
 tests/test-qapi-gen-timestamp ;
 tests/test-qapi-gen-timestamp: $(SRC_PATH)/tests/qapi-schema/qapi-schema-test.json $(qapi-py)
-	$(call quiet-command,$(PYTHON_UTF8) $(SRC_PATH)/scripts/qapi-gen.py \
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-gen.py \
 		-o tests -p "test-" $<, \
 		"GEN","$(@:%-timestamp=%)")
 	@>$@
 
 tests/qapi-schema/doc-good.test.texi: $(SRC_PATH)/tests/qapi-schema/doc-good.json $(qapi-py)
-	$(call quiet-command,$(PYTHON_UTF8) $(SRC_PATH)/scripts/qapi-gen.py \
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-gen.py \
 		-o tests/qapi-schema -p "doc-good-" $<, \
 		"GEN","$@")
 	@mv tests/qapi-schema/doc-good-qapi-doc.texi $@
@@ -927,7 +927,7 @@  check-tests/qemu-iotests-quick.sh: tests/qemu-iotests-quick.sh qemu-img$(EXESUF)
 .PHONY: $(patsubst %, check-%, $(check-qapi-schema-y))
 $(patsubst %, check-%, $(check-qapi-schema-y)): check-%.json: $(SRC_PATH)/%.json
 	$(call quiet-command, PYTHONPATH=$(SRC_PATH)/scripts \
-		$(PYTHON_UTF8) $(SRC_PATH)/tests/qapi-schema/test-qapi.py \
+		$(PYTHON) $(SRC_PATH)/tests/qapi-schema/test-qapi.py \
 		$^ >$*.test.out 2>$*.test.err; \
 		echo $$? >$*.test.exit, \
 		"TEST","$*.out")