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Re: [PULL 09/14] qmp: Move dispatcher to a coroutine
|
From: |
Kevin Wolf |
|
Subject: |
Re: [PULL 09/14] qmp: Move dispatcher to a coroutine |
|
Date: |
Mon, 12 Oct 2020 13:25:06 +0200 |
Am 12.10.2020 um 12:47 hat Alex Bennée geschrieben:
>
> Markus Armbruster <armbru@redhat.com> writes:
>
> > From: Kevin Wolf <kwolf@redhat.com>
> >
> > 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.
>
> This subtly changes the replay behaviour leading to a hang in:
>
> 10:55:18 [alex.bennee@hackbox2:~/l/q/b/bisect] (625581c2…)|✚1(+1/-1) +
> ./tests/venv/bin/avocado run
> tests/acceptance/replay_kernel.py:ReplayKernel.test_arm_virt
> Fetching asset from
> tests/acceptance/replay_kernel.py:ReplayKernel.test_arm_virt
> JOB ID : ec11fd2544f06e6c0d421f16afa757b49f7ed734
> JOB LOG :
> /home/alex.bennee/avocado/job-results/job-2020-10-12T11.40-ec11fd2/job.log
> (1/1) tests/acceptance/replay_kernel.py:ReplayKernel.test_arm_virt: ERROR:
> Could not perform graceful shutdown (26.27 s)
> RESULTS : PASS 0 | ERROR 1 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 |
> CANCEL 0
> JOB TIME : 27.77 s
>
> Looking at the log:
>
> 2020-10-12 11:40:31,426 __init__ L0085 DEBUG| [ 3.887411]
> rtc-pl031 9010000.pl031: setting system clock to 2020-10-12 10:40:31 UTC
> (1602499231)
> 2020-10-12 11:40:31,428 __init__ L0085 DEBUG| [ 3.887431]
> sr_init: No PMIC hook to init smartreflex
> 2020-10-12 11:40:31,447 __init__ L0085 DEBUG| [ 3.897193]
> uart-pl011 9000000.pl011: no DMA platform data
> 2020-10-12 11:40:31,460 __init__ L0085 DEBUG| [ 3.897242] md:
> Waiting for all devices to be available before autodetect
> 2020-10-12 11:40:31,462 __init__ L0085 DEBUG| [ 3.897259] md: If
> you don't use raid, use raid=noautodetect
> 2020-10-12 11:40:31,475 __init__ L0085 DEBUG| [ 3.897819] md:
> Autodetecting RAID arrays.
> 2020-10-12 11:40:31,476 __init__ L0085 DEBUG| [ 3.897832] md:
> autorun ...
> 2020-10-12 11:40:31,477 __init__ L0085 DEBUG| [ 3.897842] md:
> ... autorun DONE.
> 2020-10-12 11:40:31,483 __init__ L0085 DEBUG| [ 3.897962] VFS:
> Cannot open root device "(null)" or unknown-block(0,0): error -6
> 2020-10-12 11:40:31,483 qmp L0245 DEBUG| >>> {'execute':
> 'quit'}
> 2020-10-12 11:40:31,495 qmp L0145 DEBUG| <<< {'timestamp':
> {'seconds': 1602499231, 'microseconds': 493379}, 'event': 'SHUTDOWN', 'data':
> {'guest': True, 'reason': 'guest-reset'}}
> 2020-10-12 11:40:31,733 machine L0325 WARNI| qemu received signal
> 6; command: "./qemu-system-arm -display none -vga none -chardev
> socket,id=mon,path=/var/tmp/tmpzls53khe/qemu-8487-monitor.sock -mon
> chardev=mon,mode=control -machine virt -chardev
> socket,id=console,path=/var/tmp/tmpzls53khe/qemu-8487-console.sock,server,nowait
> -serial chardev:console -icount
> shift=1,rr=record,rrfile=/var/tmp/avocado_n00stdrf/avocado_job_aw60qdul/1-tests_acceptance_replay_kernel.py_ReplayKernel.test_arm_virt/replay.bin
> -kernel
> /home/alex.bennee/avocado/data/cache/by_location/62750ce9e069e69e6a7ff04ff54c382ee660b92a/vmlinuz
> -append printk.time=1 panic=-1 console=ttyAMA0 -net none -no-reboot"
This looks like a crash (SIGABRT) rather than a hang. Do you have a
stack trace for the crashed process?
Kevin
> 2020-10-12 11:40:31,734 stacktrace L0039 ERROR|
> 2020-10-12 11:40:31,734 stacktrace L0042 ERROR| Reproduced traceback
> from:
> /home/alex.bennee/lsrc/qemu.git/builds/bisect/tests/venv/lib/python3.6/site-packages/avocado/core/test.py:767
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR| Traceback (most
> recent call last):
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/python/qemu/machine.py", line 435, in
> _do_shutdown
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR|
> self._soft_shutdown(timeout, has_quit)
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/python/qemu/machine.py", line 415, in
> _soft_shutdown
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR|
> self._qmp.cmd('quit')
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/python/qemu/qmp.py", line 266, in cmd
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR| return
> self.cmd_obj(qmp_cmd)
> 2020-10-12 11:40:31,735 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/python/qemu/qmp.py", line 249, in cmd_obj
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| raise
> QMPConnectError("Unexpected empty reply from server")
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR|
> qemu.qmp.QMPConnectError: Unexpected empty reply from server
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR|
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| The above exception
> was the direct cause of the following exception:
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR|
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| Traceback (most
> recent call last):
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/builds/bisect/tests/acceptance/replay_kernel.py",
> line 128, in test_arm_virt
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR|
> self.run_rr(kernel_path, kernel_command_line, console_pattern, shift=1)
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/builds/bisect/tests/acceptance/replay_kernel.py",
> line 71, in run_rr
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| True, shift,
> args, replay_path)
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/builds/bisect/tests/acceptance/replay_kernel.py",
> line 57, in run_vm
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| vm.shutdown()
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/python/qemu/machine.py", line 465, in
> shutdown
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR|
> self._do_shutdown(timeout, has_quit)
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| File
> "/home/alex.bennee/lsrc/qemu.git/python/qemu/machine.py", line 439, in
> _do_shutdown
> 2020-10-12 11:40:31,736 stacktrace L0045 ERROR| from exc
> 2020-10-12 11:40:31,737 stacktrace L0045 ERROR|
> qemu.machine.AbnormalShutdown: Could not perform graceful shutdown
>
> The commit before:
>
> 2020-10-12 11:44:02,803 __init__ L0085 DEBUG| [ 3.897837] md:
> ... autorun DONE.
> 2020-10-12 11:44:02,806 __init__ L0085 DEBUG| [ 3.897958] VFS:
> Cannot open root device "(null)" or unknown-block(0,0): error -6
> 2020-10-12 11:44:02,806 qmp L0245 DEBUG| >>> {'execute':
> 'quit'}
> 2020-10-12 11:44:02,814 qmp L0250 DEBUG| <<< {'return': {}}
> 2020-10-12 11:44:02,879 replay_kernel L0059 INFO | finished the
> recording with log size 237596 bytes
> 2020-10-12 11:44:02,879 replay_kernel L0064 INFO | elapsed time 24.35 sec
> 2020-10-12 11:44:02,888 replay_kernel L0044 INFO | replaying the
> execution...
> 2020-10-12 11:44:02,889 machine L0362 DEBUG| VM launch command:
> './qemu-system-arm -display none -vga none -chardev
> socket,id=mon,path=/var/tmp/tmpihqswp6_/qemu-7747-monitor.sock -mon
> chardev=mon,mode=control -machine virt -chardev
> socket,id=console,path=/var/tmp/tmpihqswp6_/qemu-7747-console.sock,server,nowait
> -serial chardev:console
> -icount
> shift=1,rr=replay,rrfile=/var/tmp/avocado_o3pfy2he/avocado_job_nf30vjqg/1-tests_acceptance_replay_kernel.py_ReplayKernel.test_arm_virt/replay.bin
> -kernel
> /home/alex.bennee/avocado/data/cache/by_location/62750ce9e069e69e6a7ff04ff54c382ee660b92a/vmlinuz
> -append printk.time=1 panic=-1 console=ttyAMA0 -net none -no-reboot'
> 2020-10-12 11:44:03,001 qmp L0245 DEBUG| >>> {'execute':
> 'qmp_capabilities'}
> 2020-10-12 11:44:03,172 qmp L0250 DEBUG| <<< {'return': {}}
> 2020-10-12 11:44:04,899 __init__ L0085 DEBUG| [ 0.000000]
> Booting Linux on physical CPU 0x0
> 2020-10-12 11:44:04,904 __init__ L0085 DEBUG| [ 0.000000] Linux
> version 4.18.16-300.fc29.armv7hl
> (mockbuild@buildvm-armv7-06.arm.fedoraproject.org) (gcc version 8.2.1
> 20180801 (Red Hat 8.2.1-2) (GCC)) #1 SMP Sun Oct 21 00:56:28 UTC 2018
>
>
> >
> > 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>
> > ---
> > include/qapi/qmp/dispatch.h | 1 +
> > monitor/monitor-internal.h | 6 +-
> > monitor/monitor.c | 55 +++++++++++++---
> > monitor/qmp.c | 122 +++++++++++++++++++++++++++---------
> > qapi/qmp-dispatch.c | 63 +++++++++++++++++--
> > qapi/qmp-registry.c | 3 +
> > util/aio-posix.c | 8 ++-
> > 7 files changed, 213 insertions(+), 45 deletions(-)
> >
> > diff --git a/include/qapi/qmp/dispatch.h b/include/qapi/qmp/dispatch.h
> > index 9fd2b720a7..af8d96c570 100644
> > --- a/include/qapi/qmp/dispatch.h
> > +++ b/include/qapi/qmp/dispatch.h
> > @@ -31,6 +31,7 @@ typedef enum QmpCommandOptions
> > typedef struct QmpCommand
> > {
> > const char *name;
> > + /* Runs in coroutine context if QCO_COROUTINE is set */
> > QmpCommandFunc *fn;
> > QmpCommandOptions options;
> > QTAILQ_ENTRY(QmpCommand) node;
> > 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);
> > diff --git a/monitor/monitor.c b/monitor/monitor.c
> > index ef68ca9d21..ceffe1a83b 100644
> > --- a/monitor/monitor.c
> > +++ b/monitor/monitor.c
> > @@ -55,8 +55,32 @@ typedef struct {
> > /* Shared monitor I/O thread */
> > IOThread *mon_iothread;
> >
> > -/* Bottom half to dispatch the requests received from I/O thread */
> > -QEMUBH *qmp_dispatcher_bh;
> > +/* Coroutine to dispatch the requests received from I/O thread */
> > +Coroutine *qmp_dispatcher_co;
> > +
> > +/* Set to true when the dispatcher coroutine should terminate */
> > +bool qmp_dispatcher_co_shutdown;
> > +
> > +/*
> > + * qmp_dispatcher_co_busy is used for synchronisation between the
> > + * monitor thread and the main thread to ensure that the dispatcher
> > + * coroutine never gets scheduled a second time when it's already
> > + * scheduled (scheduling the same coroutine twice is forbidden).
> > + *
> > + * It is true if the coroutine is active and processing requests.
> > + * Additional requests may then be pushed onto mon->qmp_requests,
> > + * and @qmp_dispatcher_co_shutdown may be set without further ado.
> > + * @qmp_dispatcher_co_busy must not be woken up in this case.
> > + *
> > + * If false, you also have to set @qmp_dispatcher_co_busy to true and
> > + * wake up @qmp_dispatcher_co after pushing the new requests.
> > + *
> > + * The coroutine will automatically change this variable back to false
> > + * before it yields. Nobody else may set the variable to false.
> > + *
> > + * Access must be atomic for thread safety.
> > + */
> > +bool qmp_dispatcher_co_busy;
> >
> > /*
> > * Protects mon_list, monitor_qapi_event_state, coroutine_mon,
> > @@ -623,9 +647,24 @@ void monitor_cleanup(void)
> > }
> > qemu_mutex_unlock(&monitor_lock);
> >
> > - /* QEMUBHs needs to be deleted before destroying the I/O thread */
> > - qemu_bh_delete(qmp_dispatcher_bh);
> > - qmp_dispatcher_bh = NULL;
> > + /*
> > + * The dispatcher needs to stop before destroying the I/O thread.
> > + *
> > + * We need to poll both qemu_aio_context and iohandler_ctx to make
> > + * sure that the dispatcher coroutine keeps making progress and
> > + * eventually terminates. qemu_aio_context is automatically
> > + * polled by calling AIO_WAIT_WHILE on it, but we must poll
> > + * iohandler_ctx manually.
> > + */
> > + qmp_dispatcher_co_shutdown = true;
> > + if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) {
> > + aio_co_wake(qmp_dispatcher_co);
> > + }
> > +
> > + AIO_WAIT_WHILE(qemu_get_aio_context(),
> > + (aio_poll(iohandler_get_aio_context(), false),
> > + qatomic_mb_read(&qmp_dispatcher_co_busy)));
> > +
> > if (mon_iothread) {
> > iothread_destroy(mon_iothread);
> > mon_iothread = NULL;
> > @@ -649,9 +688,9 @@ void monitor_init_globals_core(void)
> > * have commands assuming that context. It would be nice to get
> > * rid of those assumptions.
> > */
> > - qmp_dispatcher_bh = aio_bh_new(iohandler_get_aio_context(),
> > - monitor_qmp_bh_dispatcher,
> > - NULL);
> > + qmp_dispatcher_co = qemu_coroutine_create(monitor_qmp_dispatcher_co,
> > NULL);
> > + qatomic_mb_set(&qmp_dispatcher_co_busy, true);
> > + aio_co_schedule(iohandler_get_aio_context(), qmp_dispatcher_co);
> > }
> >
> > int monitor_init(MonitorOptions *opts, bool allow_hmp, Error **errp)
> > diff --git a/monitor/qmp.c b/monitor/qmp.c
> > index e746b3575d..b42f8c6af3 100644
> > --- a/monitor/qmp.c
> > +++ b/monitor/qmp.c
> > @@ -133,6 +133,10 @@ static void monitor_qmp_respond(MonitorQMP *mon, QDict
> > *rsp)
> > }
> > }
> >
> > +/*
> > + * Runs outside of coroutine context for OOB commands, but in
> > + * coroutine context for everything else.
> > + */
> > static void monitor_qmp_dispatch(MonitorQMP *mon, QObject *req)
> > {
> > QDict *rsp;
> > @@ -206,43 +210,99 @@ static QMPRequest
> > *monitor_qmp_requests_pop_any_with_lock(void)
> > return req_obj;
> > }
> >
> > -void monitor_qmp_bh_dispatcher(void *data)
> > +void coroutine_fn monitor_qmp_dispatcher_co(void *data)
> > {
> > - QMPRequest *req_obj = monitor_qmp_requests_pop_any_with_lock();
> > + QMPRequest *req_obj = NULL;
> > QDict *rsp;
> > bool need_resume;
> > MonitorQMP *mon;
> >
> > - if (!req_obj) {
> > - return;
> > - }
> > + while (true) {
> > + assert(qatomic_mb_read(&qmp_dispatcher_co_busy) == true);
> >
> > - mon = req_obj->mon;
> > - /* qmp_oob_enabled() might change after "qmp_capabilities" */
> > - need_resume = !qmp_oob_enabled(mon) ||
> > - mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1;
> > - qemu_mutex_unlock(&mon->qmp_queue_lock);
> > - if (req_obj->req) {
> > - QDict *qdict = qobject_to(QDict, req_obj->req);
> > - QObject *id = qdict ? qdict_get(qdict, "id") : NULL;
> > - trace_monitor_qmp_cmd_in_band(qobject_get_try_str(id) ?: "");
> > - monitor_qmp_dispatch(mon, req_obj->req);
> > - } else {
> > - assert(req_obj->err);
> > - rsp = qmp_error_response(req_obj->err);
> > - req_obj->err = NULL;
> > - monitor_qmp_respond(mon, rsp);
> > - qobject_unref(rsp);
> > - }
> > + /*
> > + * Mark the dispatcher as not busy already here so that we
> > + * don't miss any new requests coming in the middle of our
> > + * processing.
> > + */
> > + qatomic_mb_set(&qmp_dispatcher_co_busy, false);
> >
> > - if (need_resume) {
> > - /* Pairs with the monitor_suspend() in handle_qmp_command() */
> > - monitor_resume(&mon->common);
> > - }
> > - qmp_request_free(req_obj);
> > + while (!(req_obj = monitor_qmp_requests_pop_any_with_lock())) {
> > + /*
> > + * No more requests to process. Wait to be reentered from
> > + * handle_qmp_command() when it pushes more requests, or
> > + * from monitor_cleanup() when it requests shutdown.
> > + */
> > + if (!qmp_dispatcher_co_shutdown) {
> > + qemu_coroutine_yield();
> >
> > - /* Reschedule instead of looping so the main loop stays responsive */
> > - qemu_bh_schedule(qmp_dispatcher_bh);
> > + /*
> > + * busy must be set to true again by whoever
> > + * rescheduled us to avoid double scheduling
> > + */
> > + assert(qatomic_xchg(&qmp_dispatcher_co_busy, false) ==
> > true);
> > + }
> > +
> > + /*
> > + * qmp_dispatcher_co_shutdown may have changed if we
> > + * yielded and were reentered from monitor_cleanup()
> > + */
> > + if (qmp_dispatcher_co_shutdown) {
> > + return;
> > + }
> > + }
> > +
> > + if (qatomic_xchg(&qmp_dispatcher_co_busy, true) == true) {
> > + /*
> > + * Someone rescheduled us (probably because a new requests
> > + * came in), but we didn't actually yield. Do that now,
> > + * only to be immediately reentered and removed from the
> > + * list of scheduled coroutines.
> > + */
> > + qemu_coroutine_yield();
> > + }
> > +
> > + /*
> > + * Move the coroutine from iohandler_ctx to qemu_aio_context for
> > + * executing the command handler so that it can make progress if it
> > + * involves an AIO_WAIT_WHILE().
> > + */
> > + aio_co_schedule(qemu_get_aio_context(), qmp_dispatcher_co);
> > + qemu_coroutine_yield();
> > +
> > + mon = req_obj->mon;
> > + /* qmp_oob_enabled() might change after "qmp_capabilities" */
> > + need_resume = !qmp_oob_enabled(mon) ||
> > + mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1;
> > + qemu_mutex_unlock(&mon->qmp_queue_lock);
> > + if (req_obj->req) {
> > + QDict *qdict = qobject_to(QDict, req_obj->req);
> > + QObject *id = qdict ? qdict_get(qdict, "id") : NULL;
> > + trace_monitor_qmp_cmd_in_band(qobject_get_try_str(id) ?: "");
> > + monitor_qmp_dispatch(mon, req_obj->req);
> > + } else {
> > + assert(req_obj->err);
> > + rsp = qmp_error_response(req_obj->err);
> > + req_obj->err = NULL;
> > + monitor_qmp_respond(mon, rsp);
> > + qobject_unref(rsp);
> > + }
> > +
> > + if (need_resume) {
> > + /* Pairs with the monitor_suspend() in handle_qmp_command() */
> > + monitor_resume(&mon->common);
> > + }
> > + qmp_request_free(req_obj);
> > +
> > + /*
> > + * Yield and reschedule so the main loop stays responsive.
> > + *
> > + * Move back to iohandler_ctx so that nested event loops for
> > + * qemu_aio_context don't start new monitor commands.
> > + */
> > + aio_co_schedule(iohandler_get_aio_context(), qmp_dispatcher_co);
> > + qemu_coroutine_yield();
> > + }
> > }
> >
> > static void handle_qmp_command(void *opaque, QObject *req, Error *err)
> > @@ -303,7 +363,9 @@ static void handle_qmp_command(void *opaque, QObject
> > *req, Error *err)
> > qemu_mutex_unlock(&mon->qmp_queue_lock);
> >
> > /* Kick the dispatcher routine */
> > - qemu_bh_schedule(qmp_dispatcher_bh);
> > + if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) {
> > + aio_co_wake(qmp_dispatcher_co);
> > + }
> > }
> >
> > static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size)
> > diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
> > index 5677ba92ca..9a2d7dd29a 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);
> > + 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));
> >
> > - cmd->fn(args, &ret, &err);
> > -
> > - monitor_set_cur(qemu_coroutine_self(), NULL);
> > + 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: */
> > diff --git a/qapi/qmp-registry.c b/qapi/qmp-registry.c
> > index d0f9a1d3e3..58c65b5052 100644
> > --- a/qapi/qmp-registry.c
> > +++ b/qapi/qmp-registry.c
> > @@ -20,6 +20,9 @@ void qmp_register_command(QmpCommandList *cmds, const
> > char *name,
> > {
> > QmpCommand *cmd = g_malloc0(sizeof(*cmd));
> >
> > + /* QCO_COROUTINE and QCO_ALLOW_OOB are incompatible for now */
> > + assert(!((options & QCO_COROUTINE) && (options & QCO_ALLOW_OOB)));
> > +
> > cmd->name = name;
> > cmd->fn = fn;
> > cmd->enabled = true;
> > diff --git a/util/aio-posix.c b/util/aio-posix.c
> > index 280f27bb99..30f5354b1e 100644
> > --- a/util/aio-posix.c
> > +++ b/util/aio-posix.c
> > @@ -15,6 +15,7 @@
> >
> > #include "qemu/osdep.h"
> > #include "block/block.h"
> > +#include "qemu/main-loop.h"
> > #include "qemu/rcu.h"
> > #include "qemu/rcu_queue.h"
> > #include "qemu/sockets.h"
> > @@ -558,8 +559,13 @@ bool aio_poll(AioContext *ctx, bool blocking)
> > * There cannot be two concurrent aio_poll calls for the same
> > AioContext (or
> > * an aio_poll concurrent with a GSource prepare/check/dispatch
> > callback).
> > * We rely on this below to avoid slow locked accesses to
> > ctx->notify_me.
> > + *
> > + * aio_poll() may only be called in the AioContext's thread.
> > iohandler_ctx
> > + * is special in that it runs in the main thread, but that thread's
> > context
> > + * is qemu_aio_context.
> > */
> > - assert(in_aio_context_home_thread(ctx));
> > + assert(in_aio_context_home_thread(ctx == iohandler_get_aio_context() ?
> > + qemu_get_aio_context() : ctx));
> >
> > qemu_lockcnt_inc(&ctx->list_lock);
>
>
> --
> Alex Bennée
>
- [PULL 00/14] Monitor patches for 2020-10-09, Markus Armbruster, 2020/10/09
- [PULL 02/14] monitor: Add Monitor parameter to monitor_get_cpu_index(), Markus Armbruster, 2020/10/09
- [PULL 06/14] qmp: Call monitor_set_cur() only in qmp_dispatch(), Markus Armbruster, 2020/10/09
- [PULL 05/14] qmp: Assert that no other monitor is active, Markus Armbruster, 2020/10/09
- [PULL 12/14] block: Add bdrv_co_enter()/leave(), Markus Armbruster, 2020/10/09
- [PULL 14/14] block: Convert 'block_resize' to coroutine, Markus Armbruster, 2020/10/09
- [PULL 01/14] monitor: Add Monitor parameter to monitor_set_cpu(), Markus Armbruster, 2020/10/09
- [PULL 04/14] hmp: Update current monitor only in handle_hmp_command(), Markus Armbruster, 2020/10/09
- [PULL 09/14] qmp: Move dispatcher to a coroutine, Markus Armbruster, 2020/10/09
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Alex Bennée, 2020/10/12
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine,
Kevin Wolf <=
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Philippe Mathieu-Daudé, 2020/10/12
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Kevin Wolf, 2020/10/12
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Alex Bennée, 2020/10/12
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Ben Widawsky, 2020/10/12
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Philippe Mathieu-Daudé, 2020/10/13
- Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Kevin Wolf, 2020/10/13
Re: [PULL 09/14] qmp: Move dispatcher to a coroutine, Volker Rümelin, 2020/10/17
[PULL 07/14] monitor: Make current monitor a per-coroutine property, Markus Armbruster, 2020/10/09