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authorKevin Wolf <kwolf@redhat.com>2020-10-05 17:58:50 +0200
committerMarkus Armbruster <armbru@redhat.com>2020-10-09 07:08:20 +0200
commit9ce44e2ce267caf5559904a201aa1986b0a8326b (patch)
tree7435b0a31a7b52eedfaa544c39d13e186b4175b9 /qapi/qmp-dispatch.c
parent04f22362f14b028c2632ce01e74e6a78c2b45e89 (diff)
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qmp: Move dispatcher to a coroutine
This moves the QMP dispatcher to a coroutine and runs all QMP command handlers that declare 'coroutine': true in coroutine context so they can avoid blocking the main loop while doing I/O or waiting for other events. For commands that are not declared safe to run in a coroutine, the dispatcher drops out of coroutine context by calling the QMP command handler from a bottom half. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20201005155855.256490-10-kwolf@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
Diffstat (limited to 'qapi/qmp-dispatch.c')
-rw-r--r--qapi/qmp-dispatch.c65
1 files changed, 60 insertions, 5 deletions
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index 5677ba9..9a2d7dd 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -12,12 +12,16 @@
*/
#include "qemu/osdep.h"
+
+#include "block/aio.h"
#include "qapi/error.h"
#include "qapi/qmp/dispatch.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
#include "sysemu/runstate.h"
#include "qapi/qmp/qbool.h"
+#include "qemu/coroutine.h"
+#include "qemu/main-loop.h"
static QDict *qmp_dispatch_check_obj(QDict *dict, bool allow_oob,
Error **errp)
@@ -88,6 +92,30 @@ bool qmp_is_oob(const QDict *dict)
&& !qdict_haskey(dict, "execute");
}
+typedef struct QmpDispatchBH {
+ const QmpCommand *cmd;
+ Monitor *cur_mon;
+ QDict *args;
+ QObject **ret;
+ Error **errp;
+ Coroutine *co;
+} QmpDispatchBH;
+
+static void do_qmp_dispatch_bh(void *opaque)
+{
+ QmpDispatchBH *data = opaque;
+
+ assert(monitor_cur() == NULL);
+ monitor_set_cur(qemu_coroutine_self(), data->cur_mon);
+ data->cmd->fn(data->args, data->ret, data->errp);
+ monitor_set_cur(qemu_coroutine_self(), NULL);
+ aio_co_wake(data->co);
+}
+
+/*
+ * Runs outside of coroutine context for OOB commands, but in coroutine
+ * context for everything else.
+ */
QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
bool allow_oob, Monitor *cur_mon)
{
@@ -153,12 +181,39 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
qobject_ref(args);
}
+ assert(!(oob && qemu_in_coroutine()));
assert(monitor_cur() == NULL);
- monitor_set_cur(qemu_coroutine_self(), cur_mon);
-
- cmd->fn(args, &ret, &err);
-
- monitor_set_cur(qemu_coroutine_self(), NULL);
+ if (!!(cmd->options & QCO_COROUTINE) == qemu_in_coroutine()) {
+ monitor_set_cur(qemu_coroutine_self(), cur_mon);
+ cmd->fn(args, &ret, &err);
+ monitor_set_cur(qemu_coroutine_self(), NULL);
+ } else {
+ /*
+ * Actual context doesn't match the one the command needs.
+ *
+ * Case 1: we are in coroutine context, but command does not
+ * have QCO_COROUTINE. We need to drop out of coroutine
+ * context for executing it.
+ *
+ * Case 2: we are outside coroutine context, but command has
+ * QCO_COROUTINE. Can't actually happen, because we get here
+ * outside coroutine context only when executing a command
+ * out of band, and OOB commands never have QCO_COROUTINE.
+ */
+ assert(!oob && qemu_in_coroutine() && !(cmd->options & QCO_COROUTINE));
+
+ QmpDispatchBH data = {
+ .cur_mon = cur_mon,
+ .cmd = cmd,
+ .args = args,
+ .ret = &ret,
+ .errp = &err,
+ .co = qemu_coroutine_self(),
+ };
+ aio_bh_schedule_oneshot(qemu_get_aio_context(), do_qmp_dispatch_bh,
+ &data);
+ qemu_coroutine_yield();
+ }
qobject_unref(args);
if (err) {
/* or assert(!ret) after reviewing all handlers: */