Commit 05875687 authored by Markus Armbruster's avatar Markus Armbruster
Browse files

qmp: Dumb down how we run QMP command registration 



The way we get QMP commands registered is high tech:

* qapi-commands.py generates qmp_init_marshal() that does the actual work

* it also generates the magic to register it as a MODULE_INIT_QAPI
  function, so it runs when someone calls
  module_call_init(MODULE_INIT_QAPI)

* main() calls module_call_init()

QEMU needs to register a few non-qapified commands.  Same high tech
works: monitor.c has its own qmp_init_marshal() along with the magic
to make it run in module_call_init(MODULE_INIT_QAPI).

QEMU also needs to unregister commands that are not wanted in this
build's configuration (commit 5032a16d).  Simple enough:
qmp_unregister_commands_hack().  The difficulty is to make it run
after the generated qmp_init_marshal().  We can't simply run it in
monitor.c's qmp_init_marshal(), because the order in which the
registered functions run is indeterminate.  So qmp_init_marshal()
registers qmp_unregister_commands_hack() separately.  Since
registering *appends* to the list of registered functions, this will
make it run after all the functions that have been registered already.

I suspect it takes a long and expensive computer science education to
not find this silly.

Dumb it down as follows:

* Drop MODULE_INIT_QAPI entirely

* Give the generated qmp_init_marshal() external linkage.

* Call it instead of module_call_init(MODULE_INIT_QAPI)

* Except in QEMU proper, call new monitor_init_qmp_commands() that in
  turn calls the generated qmp_init_marshal(), registers the
  additional commands and unregisters the unwanted ones.

Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1488544368-30622-5-git-send-email-armbru@redhat.com>
parent f66e7ac8

include/monitor/monitor.h

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ extern Monitor *cur_mon; 


bool monitor_cur_is_qmp(void);



void monitor_init_qmp_commands(void);

void monitor_init(Chardev *chr, int flags);

void monitor_cleanup(void);

include/qemu/module.h

+0 −2
Original line number Diff line number Diff line
@@ -42,7 +42,6 @@ static void __attribute__((constructor)) do_qemu_init_ ## function(void) \ 
typedef enum {

    MODULE_INIT_BLOCK,

    MODULE_INIT_OPTS,

    MODULE_INIT_QAPI,

    MODULE_INIT_QOM,

    MODULE_INIT_TRACE,

    MODULE_INIT_MAX
@@ -50,7 +49,6 @@ typedef enum { 


#define block_init(function) module_init(function, MODULE_INIT_BLOCK)

#define opts_init(function) module_init(function, MODULE_INIT_OPTS)

#define qapi_init(function) module_init(function, MODULE_INIT_QAPI)

#define type_init(function) module_init(function, MODULE_INIT_QOM)

#define trace_init(function) module_init(function, MODULE_INIT_TRACE)

monitor.c

+4 −5
Original line number Diff line number Diff line
@@ -997,8 +997,10 @@ static void qmp_unregister_commands_hack(void) 
#endif

}



static void qmp_init_marshal(void)

void monitor_init_qmp_commands(void)

{

    qmp_init_marshal();



    qmp_register_command("query-qmp-schema", qmp_query_qmp_schema,

                         QCO_NO_OPTIONS);

    qmp_register_command("device_add", qmp_device_add,
@@ -1006,12 +1008,9 @@ static void qmp_init_marshal(void) 
    qmp_register_command("netdev_add", qmp_netdev_add,

                         QCO_NO_OPTIONS);



    /* call it after the rest of qapi_init() */

    register_module_init(qmp_unregister_commands_hack, MODULE_INIT_QAPI);

    qmp_unregister_commands_hack();

}



qapi_init(qmp_init_marshal);



/* set the current CPU defined by the user */

int monitor_set_cpu(int cpu_index)

{

qga/main.c

+1 −1
Original line number Diff line number Diff line
@@ -1321,7 +1321,7 @@ int main(int argc, char **argv) 


    config->log_level = G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL;



    module_call_init(MODULE_INIT_QAPI);

    qmp_init_marshal();



    init_dfl_pathnames();

    config_load(config);

scripts/qapi-commands.py

+2 −3
Original line number Diff line number Diff line
@@ -208,14 +208,12 @@ def gen_register_command(name, success_response): 
def gen_registry(registry):

    ret = mcgen('''



static void qmp_init_marshal(void)

void qmp_init_marshal(void)

{

''')

    ret += registry

    ret += mcgen('''

}



qapi_init(qmp_init_marshal);

''')

    return ret
@@ -308,6 +306,7 @@ fdecl.write(mcgen(''' 
#include "qapi/qmp/qdict.h"

#include "qapi/error.h"



void qmp_init_marshal(void);

''',

                  prefix=prefix))