From 9ce44e2ce267caf5559904a201aa1986b0a8326b Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 5 Oct 2020 17:58:50 +0200 Subject: 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 Reviewed-by: Markus Armbruster Message-Id: <20201005155855.256490-10-kwolf@redhat.com> Reviewed-by: Markus Armbruster Reviewed-by: Stefan Hajnoczi Signed-off-by: Markus Armbruster --- monitor/monitor-internal.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'monitor/monitor-internal.h') diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h index b39e03b744..b55d6df07f 100644 --- a/monitor/monitor-internal.h +++ b/monitor/monitor-internal.h @@ -155,7 +155,9 @@ static inline bool monitor_is_qmp(const Monitor *mon) typedef QTAILQ_HEAD(MonitorList, Monitor) MonitorList; extern IOThread *mon_iothread; -extern QEMUBH *qmp_dispatcher_bh; +extern Coroutine *qmp_dispatcher_co; +extern bool qmp_dispatcher_co_shutdown; +extern bool qmp_dispatcher_co_busy; extern QmpCommandList qmp_commands, qmp_cap_negotiation_commands; extern QemuMutex monitor_lock; extern MonitorList mon_list; @@ -173,7 +175,7 @@ void monitor_fdsets_cleanup(void); void qmp_send_response(MonitorQMP *mon, const QDict *rsp); void monitor_data_destroy_qmp(MonitorQMP *mon); -void monitor_qmp_bh_dispatcher(void *data); +void coroutine_fn monitor_qmp_dispatcher_co(void *data); int get_monitor_def(int64_t *pval, const char *name); void help_cmd(Monitor *mon, const char *name); -- cgit 1.4.1 From bb4b9ead95c3aaca84823e28dd9f11ccaa875c14 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 5 Oct 2020 17:58:51 +0200 Subject: hmp: Add support for coroutine command handlers Often, QMP command handlers are not only called to handle QMP commands, but also from a corresponding HMP command handler. In order to give them a consistent environment, optionally run HMP command handlers in a coroutine, too. The implementation is a lot simpler than in QMP because for HMP, we still block the VM while the coroutine is running. Signed-off-by: Kevin Wolf Reviewed-by: Dr. David Alan Gilbert Message-Id: <20201005155855.256490-11-kwolf@redhat.com> Reviewed-by: Markus Armbruster Reviewed-by: Stefan Hajnoczi Signed-off-by: Markus Armbruster --- docs/devel/qapi-code-gen.txt | 4 ++-- monitor/hmp.c | 37 ++++++++++++++++++++++++++++++++----- monitor/monitor-internal.h | 1 + 3 files changed, 35 insertions(+), 7 deletions(-) (limited to 'monitor/monitor-internal.h') diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt index 4a41e36a75..c6438c6aa9 100644 --- a/docs/devel/qapi-code-gen.txt +++ b/docs/devel/qapi-code-gen.txt @@ -617,8 +617,8 @@ pitfalls are: Since the command handler may assume coroutine context, any callers other than the QMP dispatcher must also call it in coroutine context. -In particular, HMP commands calling such a QMP command handler must -enter coroutine context before calling the handler. +In particular, HMP commands calling such a QMP command handler must be +marked .coroutine = true in hmp-commands.hx. It is an error to specify both 'coroutine': true and 'allow-oob': true for a command. We don't currently have a use case for both together and diff --git a/monitor/hmp.c b/monitor/hmp.c index abaf939b2d..c5cd9d372b 100644 --- a/monitor/hmp.c +++ b/monitor/hmp.c @@ -1056,12 +1056,26 @@ fail: return NULL; } +typedef struct HandleHmpCommandCo { + Monitor *mon; + const HMPCommand *cmd; + QDict *qdict; + bool done; +} HandleHmpCommandCo; + +static void handle_hmp_command_co(void *opaque) +{ + HandleHmpCommandCo *data = opaque; + data->cmd->cmd(data->mon, data->qdict); + monitor_set_cur(qemu_coroutine_self(), NULL); + data->done = true; +} + void handle_hmp_command(MonitorHMP *mon, const char *cmdline) { QDict *qdict; const HMPCommand *cmd; const char *cmd_start = cmdline; - Monitor *old_mon; trace_handle_hmp_command(mon, cmdline); @@ -1080,10 +1094,23 @@ void handle_hmp_command(MonitorHMP *mon, const char *cmdline) return; } - /* old_mon is non-NULL when called from qmp_human_monitor_command() */ - old_mon = monitor_set_cur(qemu_coroutine_self(), &mon->common); - cmd->cmd(&mon->common, qdict); - monitor_set_cur(qemu_coroutine_self(), old_mon); + if (!cmd->coroutine) { + /* old_mon is non-NULL when called from qmp_human_monitor_command() */ + Monitor *old_mon = monitor_set_cur(qemu_coroutine_self(), &mon->common); + cmd->cmd(&mon->common, qdict); + monitor_set_cur(qemu_coroutine_self(), old_mon); + } else { + HandleHmpCommandCo data = { + .mon = &mon->common, + .cmd = cmd, + .qdict = qdict, + .done = false, + }; + Coroutine *co = qemu_coroutine_create(handle_hmp_command_co, &data); + monitor_set_cur(co, &mon->common); + aio_co_enter(qemu_get_aio_context(), co); + AIO_WAIT_WHILE(qemu_get_aio_context(), !data.done); + } qobject_unref(qdict); } diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h index b55d6df07f..ad2e64be13 100644 --- a/monitor/monitor-internal.h +++ b/monitor/monitor-internal.h @@ -74,6 +74,7 @@ typedef struct HMPCommand { const char *help; const char *flags; /* p=preconfig */ void (*cmd)(Monitor *mon, const QDict *qdict); + bool coroutine; /* * @sub_table is a list of 2nd level of commands. If it does not exist, * cmd should be used. If it exists, sub_table[?].cmd should be -- cgit 1.4.1