xref: /openbmc/qemu/job.c (revision 2fc979cb)
1 /*
2  * Background jobs (long-running operations)
3  *
4  * Copyright (c) 2011 IBM Corp.
5  * Copyright (c) 2012, 2018 Red Hat, Inc.
6  *
7  * Permission is hereby granted, free of charge, to any person obtaining a copy
8  * of this software and associated documentation files (the "Software"), to deal
9  * in the Software without restriction, including without limitation the rights
10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11  * copies of the Software, and to permit persons to whom the Software is
12  * furnished to do so, subject to the following conditions:
13  *
14  * The above copyright notice and this permission notice shall be included in
15  * all copies or substantial portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23  * THE SOFTWARE.
24  */
25 
26 #include "qemu/osdep.h"
27 #include "qapi/error.h"
28 #include "qemu/job.h"
29 #include "qemu/id.h"
30 #include "qemu/main-loop.h"
31 #include "block/aio-wait.h"
32 #include "trace-root.h"
33 #include "qapi/qapi-events-job.h"
34 
35 static QLIST_HEAD(, Job) jobs = QLIST_HEAD_INITIALIZER(jobs);
36 
37 /* Job State Transition Table */
38 bool JobSTT[JOB_STATUS__MAX][JOB_STATUS__MAX] = {
39                                     /* U, C, R, P, Y, S, W, D, X, E, N */
40     /* U: */ [JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
41     /* C: */ [JOB_STATUS_CREATED]   = {0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1},
42     /* R: */ [JOB_STATUS_RUNNING]   = {0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0},
43     /* P: */ [JOB_STATUS_PAUSED]    = {0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0},
44     /* Y: */ [JOB_STATUS_READY]     = {0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0},
45     /* S: */ [JOB_STATUS_STANDBY]   = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0},
46     /* W: */ [JOB_STATUS_WAITING]   = {0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0},
47     /* D: */ [JOB_STATUS_PENDING]   = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0},
48     /* X: */ [JOB_STATUS_ABORTING]  = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0},
49     /* E: */ [JOB_STATUS_CONCLUDED] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},
50     /* N: */ [JOB_STATUS_NULL]      = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
51 };
52 
53 bool JobVerbTable[JOB_VERB__MAX][JOB_STATUS__MAX] = {
54                                     /* U, C, R, P, Y, S, W, D, X, E, N */
55     [JOB_VERB_CANCEL]               = {0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0},
56     [JOB_VERB_PAUSE]                = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
57     [JOB_VERB_RESUME]               = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
58     [JOB_VERB_SET_SPEED]            = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
59     [JOB_VERB_COMPLETE]             = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0},
60     [JOB_VERB_FINALIZE]             = {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0},
61     [JOB_VERB_DISMISS]              = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0},
62 };
63 
64 /* Transactional group of jobs */
65 struct JobTxn {
66 
67     /* Is this txn being cancelled? */
68     bool aborting;
69 
70     /* List of jobs */
71     QLIST_HEAD(, Job) jobs;
72 
73     /* Reference count */
74     int refcnt;
75 };
76 
77 /* Right now, this mutex is only needed to synchronize accesses to job->busy
78  * and job->sleep_timer, such as concurrent calls to job_do_yield and
79  * job_enter. */
80 static QemuMutex job_mutex;
81 
82 static void job_lock(void)
83 {
84     qemu_mutex_lock(&job_mutex);
85 }
86 
87 static void job_unlock(void)
88 {
89     qemu_mutex_unlock(&job_mutex);
90 }
91 
92 static void __attribute__((__constructor__)) job_init(void)
93 {
94     qemu_mutex_init(&job_mutex);
95 }
96 
97 JobTxn *job_txn_new(void)
98 {
99     JobTxn *txn = g_new0(JobTxn, 1);
100     QLIST_INIT(&txn->jobs);
101     txn->refcnt = 1;
102     return txn;
103 }
104 
105 static void job_txn_ref(JobTxn *txn)
106 {
107     txn->refcnt++;
108 }
109 
110 void job_txn_unref(JobTxn *txn)
111 {
112     if (txn && --txn->refcnt == 0) {
113         g_free(txn);
114     }
115 }
116 
117 void job_txn_add_job(JobTxn *txn, Job *job)
118 {
119     if (!txn) {
120         return;
121     }
122 
123     assert(!job->txn);
124     job->txn = txn;
125 
126     QLIST_INSERT_HEAD(&txn->jobs, job, txn_list);
127     job_txn_ref(txn);
128 }
129 
130 static void job_txn_del_job(Job *job)
131 {
132     if (job->txn) {
133         QLIST_REMOVE(job, txn_list);
134         job_txn_unref(job->txn);
135         job->txn = NULL;
136     }
137 }
138 
139 static int job_txn_apply(Job *job, int fn(Job *))
140 {
141     AioContext *inner_ctx;
142     Job *other_job, *next;
143     JobTxn *txn = job->txn;
144     int rc = 0;
145 
146     /*
147      * Similar to job_completed_txn_abort, we take each job's lock before
148      * applying fn, but since we assume that outer_ctx is held by the caller,
149      * we need to release it here to avoid holding the lock twice - which would
150      * break AIO_WAIT_WHILE from within fn.
151      */
152     job_ref(job);
153     aio_context_release(job->aio_context);
154 
155     QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
156         inner_ctx = other_job->aio_context;
157         aio_context_acquire(inner_ctx);
158         rc = fn(other_job);
159         aio_context_release(inner_ctx);
160         if (rc) {
161             break;
162         }
163     }
164 
165     /*
166      * Note that job->aio_context might have been changed by calling fn, so we
167      * can't use a local variable to cache it.
168      */
169     aio_context_acquire(job->aio_context);
170     job_unref(job);
171     return rc;
172 }
173 
174 bool job_is_internal(Job *job)
175 {
176     return (job->id == NULL);
177 }
178 
179 static void job_state_transition(Job *job, JobStatus s1)
180 {
181     JobStatus s0 = job->status;
182     assert(s1 >= 0 && s1 < JOB_STATUS__MAX);
183     trace_job_state_transition(job, job->ret,
184                                JobSTT[s0][s1] ? "allowed" : "disallowed",
185                                JobStatus_str(s0), JobStatus_str(s1));
186     assert(JobSTT[s0][s1]);
187     job->status = s1;
188 
189     if (!job_is_internal(job) && s1 != s0) {
190         qapi_event_send_job_status_change(job->id, job->status);
191     }
192 }
193 
194 int job_apply_verb(Job *job, JobVerb verb, Error **errp)
195 {
196     JobStatus s0 = job->status;
197     assert(verb >= 0 && verb < JOB_VERB__MAX);
198     trace_job_apply_verb(job, JobStatus_str(s0), JobVerb_str(verb),
199                          JobVerbTable[verb][s0] ? "allowed" : "prohibited");
200     if (JobVerbTable[verb][s0]) {
201         return 0;
202     }
203     error_setg(errp, "Job '%s' in state '%s' cannot accept command verb '%s'",
204                job->id, JobStatus_str(s0), JobVerb_str(verb));
205     return -EPERM;
206 }
207 
208 JobType job_type(const Job *job)
209 {
210     return job->driver->job_type;
211 }
212 
213 const char *job_type_str(const Job *job)
214 {
215     return JobType_str(job_type(job));
216 }
217 
218 bool job_is_cancelled(Job *job)
219 {
220     return job->cancelled;
221 }
222 
223 bool job_is_ready(Job *job)
224 {
225     switch (job->status) {
226     case JOB_STATUS_UNDEFINED:
227     case JOB_STATUS_CREATED:
228     case JOB_STATUS_RUNNING:
229     case JOB_STATUS_PAUSED:
230     case JOB_STATUS_WAITING:
231     case JOB_STATUS_PENDING:
232     case JOB_STATUS_ABORTING:
233     case JOB_STATUS_CONCLUDED:
234     case JOB_STATUS_NULL:
235         return false;
236     case JOB_STATUS_READY:
237     case JOB_STATUS_STANDBY:
238         return true;
239     default:
240         g_assert_not_reached();
241     }
242     return false;
243 }
244 
245 bool job_is_completed(Job *job)
246 {
247     switch (job->status) {
248     case JOB_STATUS_UNDEFINED:
249     case JOB_STATUS_CREATED:
250     case JOB_STATUS_RUNNING:
251     case JOB_STATUS_PAUSED:
252     case JOB_STATUS_READY:
253     case JOB_STATUS_STANDBY:
254         return false;
255     case JOB_STATUS_WAITING:
256     case JOB_STATUS_PENDING:
257     case JOB_STATUS_ABORTING:
258     case JOB_STATUS_CONCLUDED:
259     case JOB_STATUS_NULL:
260         return true;
261     default:
262         g_assert_not_reached();
263     }
264     return false;
265 }
266 
267 static bool job_started(Job *job)
268 {
269     return job->co;
270 }
271 
272 static bool job_should_pause(Job *job)
273 {
274     return job->pause_count > 0;
275 }
276 
277 Job *job_next(Job *job)
278 {
279     if (!job) {
280         return QLIST_FIRST(&jobs);
281     }
282     return QLIST_NEXT(job, job_list);
283 }
284 
285 Job *job_get(const char *id)
286 {
287     Job *job;
288 
289     QLIST_FOREACH(job, &jobs, job_list) {
290         if (job->id && !strcmp(id, job->id)) {
291             return job;
292         }
293     }
294 
295     return NULL;
296 }
297 
298 static void job_sleep_timer_cb(void *opaque)
299 {
300     Job *job = opaque;
301 
302     job_enter(job);
303 }
304 
305 void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
306                  AioContext *ctx, int flags, BlockCompletionFunc *cb,
307                  void *opaque, Error **errp)
308 {
309     Job *job;
310 
311     if (job_id) {
312         if (flags & JOB_INTERNAL) {
313             error_setg(errp, "Cannot specify job ID for internal job");
314             return NULL;
315         }
316         if (!id_wellformed(job_id)) {
317             error_setg(errp, "Invalid job ID '%s'", job_id);
318             return NULL;
319         }
320         if (job_get(job_id)) {
321             error_setg(errp, "Job ID '%s' already in use", job_id);
322             return NULL;
323         }
324     } else if (!(flags & JOB_INTERNAL)) {
325         error_setg(errp, "An explicit job ID is required");
326         return NULL;
327     }
328 
329     job = g_malloc0(driver->instance_size);
330     job->driver        = driver;
331     job->id            = g_strdup(job_id);
332     job->refcnt        = 1;
333     job->aio_context   = ctx;
334     job->busy          = false;
335     job->paused        = true;
336     job->pause_count   = 1;
337     job->auto_finalize = !(flags & JOB_MANUAL_FINALIZE);
338     job->auto_dismiss  = !(flags & JOB_MANUAL_DISMISS);
339     job->cb            = cb;
340     job->opaque        = opaque;
341 
342     notifier_list_init(&job->on_finalize_cancelled);
343     notifier_list_init(&job->on_finalize_completed);
344     notifier_list_init(&job->on_pending);
345     notifier_list_init(&job->on_ready);
346 
347     job_state_transition(job, JOB_STATUS_CREATED);
348     aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
349                    QEMU_CLOCK_REALTIME, SCALE_NS,
350                    job_sleep_timer_cb, job);
351 
352     QLIST_INSERT_HEAD(&jobs, job, job_list);
353 
354     /* Single jobs are modeled as single-job transactions for sake of
355      * consolidating the job management logic */
356     if (!txn) {
357         txn = job_txn_new();
358         job_txn_add_job(txn, job);
359         job_txn_unref(txn);
360     } else {
361         job_txn_add_job(txn, job);
362     }
363 
364     return job;
365 }
366 
367 void job_ref(Job *job)
368 {
369     ++job->refcnt;
370 }
371 
372 void job_unref(Job *job)
373 {
374     if (--job->refcnt == 0) {
375         assert(job->status == JOB_STATUS_NULL);
376         assert(!timer_pending(&job->sleep_timer));
377         assert(!job->txn);
378 
379         if (job->driver->free) {
380             job->driver->free(job);
381         }
382 
383         QLIST_REMOVE(job, job_list);
384 
385         error_free(job->err);
386         g_free(job->id);
387         g_free(job);
388     }
389 }
390 
391 void job_progress_update(Job *job, uint64_t done)
392 {
393     progress_work_done(&job->progress, done);
394 }
395 
396 void job_progress_set_remaining(Job *job, uint64_t remaining)
397 {
398     progress_set_remaining(&job->progress, remaining);
399 }
400 
401 void job_progress_increase_remaining(Job *job, uint64_t delta)
402 {
403     progress_increase_remaining(&job->progress, delta);
404 }
405 
406 void job_event_cancelled(Job *job)
407 {
408     notifier_list_notify(&job->on_finalize_cancelled, job);
409 }
410 
411 void job_event_completed(Job *job)
412 {
413     notifier_list_notify(&job->on_finalize_completed, job);
414 }
415 
416 static void job_event_pending(Job *job)
417 {
418     notifier_list_notify(&job->on_pending, job);
419 }
420 
421 static void job_event_ready(Job *job)
422 {
423     notifier_list_notify(&job->on_ready, job);
424 }
425 
426 static void job_event_idle(Job *job)
427 {
428     notifier_list_notify(&job->on_idle, job);
429 }
430 
431 void job_enter_cond(Job *job, bool(*fn)(Job *job))
432 {
433     if (!job_started(job)) {
434         return;
435     }
436     if (job->deferred_to_main_loop) {
437         return;
438     }
439 
440     job_lock();
441     if (job->busy) {
442         job_unlock();
443         return;
444     }
445 
446     if (fn && !fn(job)) {
447         job_unlock();
448         return;
449     }
450 
451     assert(!job->deferred_to_main_loop);
452     timer_del(&job->sleep_timer);
453     job->busy = true;
454     job_unlock();
455     aio_co_enter(job->aio_context, job->co);
456 }
457 
458 void job_enter(Job *job)
459 {
460     job_enter_cond(job, NULL);
461 }
462 
463 /* Yield, and schedule a timer to reenter the coroutine after @ns nanoseconds.
464  * Reentering the job coroutine with job_enter() before the timer has expired
465  * is allowed and cancels the timer.
466  *
467  * If @ns is (uint64_t) -1, no timer is scheduled and job_enter() must be
468  * called explicitly. */
469 static void coroutine_fn job_do_yield(Job *job, uint64_t ns)
470 {
471     job_lock();
472     if (ns != -1) {
473         timer_mod(&job->sleep_timer, ns);
474     }
475     job->busy = false;
476     job_event_idle(job);
477     job_unlock();
478     qemu_coroutine_yield();
479 
480     /* Set by job_enter_cond() before re-entering the coroutine.  */
481     assert(job->busy);
482 }
483 
484 void coroutine_fn job_pause_point(Job *job)
485 {
486     assert(job && job_started(job));
487 
488     if (!job_should_pause(job)) {
489         return;
490     }
491     if (job_is_cancelled(job)) {
492         return;
493     }
494 
495     if (job->driver->pause) {
496         job->driver->pause(job);
497     }
498 
499     if (job_should_pause(job) && !job_is_cancelled(job)) {
500         JobStatus status = job->status;
501         job_state_transition(job, status == JOB_STATUS_READY
502                                   ? JOB_STATUS_STANDBY
503                                   : JOB_STATUS_PAUSED);
504         job->paused = true;
505         job_do_yield(job, -1);
506         job->paused = false;
507         job_state_transition(job, status);
508     }
509 
510     if (job->driver->resume) {
511         job->driver->resume(job);
512     }
513 }
514 
515 void job_yield(Job *job)
516 {
517     assert(job->busy);
518 
519     /* Check cancellation *before* setting busy = false, too!  */
520     if (job_is_cancelled(job)) {
521         return;
522     }
523 
524     if (!job_should_pause(job)) {
525         job_do_yield(job, -1);
526     }
527 
528     job_pause_point(job);
529 }
530 
531 void coroutine_fn job_sleep_ns(Job *job, int64_t ns)
532 {
533     assert(job->busy);
534 
535     /* Check cancellation *before* setting busy = false, too!  */
536     if (job_is_cancelled(job)) {
537         return;
538     }
539 
540     if (!job_should_pause(job)) {
541         job_do_yield(job, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + ns);
542     }
543 
544     job_pause_point(job);
545 }
546 
547 /* Assumes the block_job_mutex is held */
548 static bool job_timer_not_pending(Job *job)
549 {
550     return !timer_pending(&job->sleep_timer);
551 }
552 
553 void job_pause(Job *job)
554 {
555     job->pause_count++;
556 }
557 
558 void job_resume(Job *job)
559 {
560     assert(job->pause_count > 0);
561     job->pause_count--;
562     if (job->pause_count) {
563         return;
564     }
565 
566     /* kick only if no timer is pending */
567     job_enter_cond(job, job_timer_not_pending);
568 }
569 
570 void job_user_pause(Job *job, Error **errp)
571 {
572     if (job_apply_verb(job, JOB_VERB_PAUSE, errp)) {
573         return;
574     }
575     if (job->user_paused) {
576         error_setg(errp, "Job is already paused");
577         return;
578     }
579     job->user_paused = true;
580     job_pause(job);
581 }
582 
583 bool job_user_paused(Job *job)
584 {
585     return job->user_paused;
586 }
587 
588 void job_user_resume(Job *job, Error **errp)
589 {
590     assert(job);
591     if (!job->user_paused || job->pause_count <= 0) {
592         error_setg(errp, "Can't resume a job that was not paused");
593         return;
594     }
595     if (job_apply_verb(job, JOB_VERB_RESUME, errp)) {
596         return;
597     }
598     if (job->driver->user_resume) {
599         job->driver->user_resume(job);
600     }
601     job->user_paused = false;
602     job_resume(job);
603 }
604 
605 static void job_do_dismiss(Job *job)
606 {
607     assert(job);
608     job->busy = false;
609     job->paused = false;
610     job->deferred_to_main_loop = true;
611 
612     job_txn_del_job(job);
613 
614     job_state_transition(job, JOB_STATUS_NULL);
615     job_unref(job);
616 }
617 
618 void job_dismiss(Job **jobptr, Error **errp)
619 {
620     Job *job = *jobptr;
621     /* similarly to _complete, this is QMP-interface only. */
622     assert(job->id);
623     if (job_apply_verb(job, JOB_VERB_DISMISS, errp)) {
624         return;
625     }
626 
627     job_do_dismiss(job);
628     *jobptr = NULL;
629 }
630 
631 void job_early_fail(Job *job)
632 {
633     assert(job->status == JOB_STATUS_CREATED);
634     job_do_dismiss(job);
635 }
636 
637 static void job_conclude(Job *job)
638 {
639     job_state_transition(job, JOB_STATUS_CONCLUDED);
640     if (job->auto_dismiss || !job_started(job)) {
641         job_do_dismiss(job);
642     }
643 }
644 
645 static void job_update_rc(Job *job)
646 {
647     if (!job->ret && job_is_cancelled(job)) {
648         job->ret = -ECANCELED;
649     }
650     if (job->ret) {
651         if (!job->err) {
652             error_setg(&job->err, "%s", strerror(-job->ret));
653         }
654         job_state_transition(job, JOB_STATUS_ABORTING);
655     }
656 }
657 
658 static void job_commit(Job *job)
659 {
660     assert(!job->ret);
661     if (job->driver->commit) {
662         job->driver->commit(job);
663     }
664 }
665 
666 static void job_abort(Job *job)
667 {
668     assert(job->ret);
669     if (job->driver->abort) {
670         job->driver->abort(job);
671     }
672 }
673 
674 static void job_clean(Job *job)
675 {
676     if (job->driver->clean) {
677         job->driver->clean(job);
678     }
679 }
680 
681 static int job_finalize_single(Job *job)
682 {
683     assert(job_is_completed(job));
684 
685     /* Ensure abort is called for late-transactional failures */
686     job_update_rc(job);
687 
688     if (!job->ret) {
689         job_commit(job);
690     } else {
691         job_abort(job);
692     }
693     job_clean(job);
694 
695     if (job->cb) {
696         job->cb(job->opaque, job->ret);
697     }
698 
699     /* Emit events only if we actually started */
700     if (job_started(job)) {
701         if (job_is_cancelled(job)) {
702             job_event_cancelled(job);
703         } else {
704             job_event_completed(job);
705         }
706     }
707 
708     job_txn_del_job(job);
709     job_conclude(job);
710     return 0;
711 }
712 
713 static void job_cancel_async(Job *job, bool force)
714 {
715     if (job->user_paused) {
716         /* Do not call job_enter here, the caller will handle it.  */
717         if (job->driver->user_resume) {
718             job->driver->user_resume(job);
719         }
720         job->user_paused = false;
721         assert(job->pause_count > 0);
722         job->pause_count--;
723     }
724     job->cancelled = true;
725     /* To prevent 'force == false' overriding a previous 'force == true' */
726     job->force_cancel |= force;
727 }
728 
729 static void job_completed_txn_abort(Job *job)
730 {
731     AioContext *outer_ctx = job->aio_context;
732     AioContext *ctx;
733     JobTxn *txn = job->txn;
734     Job *other_job;
735 
736     if (txn->aborting) {
737         /*
738          * We are cancelled by another job, which will handle everything.
739          */
740         return;
741     }
742     txn->aborting = true;
743     job_txn_ref(txn);
744 
745     /* We can only hold the single job's AioContext lock while calling
746      * job_finalize_single() because the finalization callbacks can involve
747      * calls of AIO_WAIT_WHILE(), which could deadlock otherwise. */
748     aio_context_release(outer_ctx);
749 
750     /* Other jobs are effectively cancelled by us, set the status for
751      * them; this job, however, may or may not be cancelled, depending
752      * on the caller, so leave it. */
753     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
754         if (other_job != job) {
755             ctx = other_job->aio_context;
756             aio_context_acquire(ctx);
757             job_cancel_async(other_job, false);
758             aio_context_release(ctx);
759         }
760     }
761     while (!QLIST_EMPTY(&txn->jobs)) {
762         other_job = QLIST_FIRST(&txn->jobs);
763         ctx = other_job->aio_context;
764         aio_context_acquire(ctx);
765         if (!job_is_completed(other_job)) {
766             assert(job_is_cancelled(other_job));
767             job_finish_sync(other_job, NULL, NULL);
768         }
769         job_finalize_single(other_job);
770         aio_context_release(ctx);
771     }
772 
773     aio_context_acquire(outer_ctx);
774 
775     job_txn_unref(txn);
776 }
777 
778 static int job_prepare(Job *job)
779 {
780     if (job->ret == 0 && job->driver->prepare) {
781         job->ret = job->driver->prepare(job);
782         job_update_rc(job);
783     }
784     return job->ret;
785 }
786 
787 static int job_needs_finalize(Job *job)
788 {
789     return !job->auto_finalize;
790 }
791 
792 static void job_do_finalize(Job *job)
793 {
794     int rc;
795     assert(job && job->txn);
796 
797     /* prepare the transaction to complete */
798     rc = job_txn_apply(job, job_prepare);
799     if (rc) {
800         job_completed_txn_abort(job);
801     } else {
802         job_txn_apply(job, job_finalize_single);
803     }
804 }
805 
806 void job_finalize(Job *job, Error **errp)
807 {
808     assert(job && job->id);
809     if (job_apply_verb(job, JOB_VERB_FINALIZE, errp)) {
810         return;
811     }
812     job_do_finalize(job);
813 }
814 
815 static int job_transition_to_pending(Job *job)
816 {
817     job_state_transition(job, JOB_STATUS_PENDING);
818     if (!job->auto_finalize) {
819         job_event_pending(job);
820     }
821     return 0;
822 }
823 
824 void job_transition_to_ready(Job *job)
825 {
826     job_state_transition(job, JOB_STATUS_READY);
827     job_event_ready(job);
828 }
829 
830 static void job_completed_txn_success(Job *job)
831 {
832     JobTxn *txn = job->txn;
833     Job *other_job;
834 
835     job_state_transition(job, JOB_STATUS_WAITING);
836 
837     /*
838      * Successful completion, see if there are other running jobs in this
839      * txn.
840      */
841     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
842         if (!job_is_completed(other_job)) {
843             return;
844         }
845         assert(other_job->ret == 0);
846     }
847 
848     job_txn_apply(job, job_transition_to_pending);
849 
850     /* If no jobs need manual finalization, automatically do so */
851     if (job_txn_apply(job, job_needs_finalize) == 0) {
852         job_do_finalize(job);
853     }
854 }
855 
856 static void job_completed(Job *job)
857 {
858     assert(job && job->txn && !job_is_completed(job));
859 
860     job_update_rc(job);
861     trace_job_completed(job, job->ret);
862     if (job->ret) {
863         job_completed_txn_abort(job);
864     } else {
865         job_completed_txn_success(job);
866     }
867 }
868 
869 /** Useful only as a type shim for aio_bh_schedule_oneshot. */
870 static void job_exit(void *opaque)
871 {
872     Job *job = (Job *)opaque;
873     AioContext *ctx;
874 
875     job_ref(job);
876     aio_context_acquire(job->aio_context);
877 
878     /* This is a lie, we're not quiescent, but still doing the completion
879      * callbacks. However, completion callbacks tend to involve operations that
880      * drain block nodes, and if .drained_poll still returned true, we would
881      * deadlock. */
882     job->busy = false;
883     job_event_idle(job);
884 
885     job_completed(job);
886 
887     /*
888      * Note that calling job_completed can move the job to a different
889      * aio_context, so we cannot cache from above. job_txn_apply takes care of
890      * acquiring the new lock, and we ref/unref to avoid job_completed freeing
891      * the job underneath us.
892      */
893     ctx = job->aio_context;
894     job_unref(job);
895     aio_context_release(ctx);
896 }
897 
898 /**
899  * All jobs must allow a pause point before entering their job proper. This
900  * ensures that jobs can be paused prior to being started, then resumed later.
901  */
902 static void coroutine_fn job_co_entry(void *opaque)
903 {
904     Job *job = opaque;
905 
906     assert(job && job->driver && job->driver->run);
907     job_pause_point(job);
908     job->ret = job->driver->run(job, &job->err);
909     job->deferred_to_main_loop = true;
910     job->busy = true;
911     aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job);
912 }
913 
914 void job_start(Job *job)
915 {
916     assert(job && !job_started(job) && job->paused &&
917            job->driver && job->driver->run);
918     job->co = qemu_coroutine_create(job_co_entry, job);
919     job->pause_count--;
920     job->busy = true;
921     job->paused = false;
922     job_state_transition(job, JOB_STATUS_RUNNING);
923     aio_co_enter(job->aio_context, job->co);
924 }
925 
926 void job_cancel(Job *job, bool force)
927 {
928     if (job->status == JOB_STATUS_CONCLUDED) {
929         job_do_dismiss(job);
930         return;
931     }
932     job_cancel_async(job, force);
933     if (!job_started(job)) {
934         job_completed(job);
935     } else if (job->deferred_to_main_loop) {
936         job_completed_txn_abort(job);
937     } else {
938         job_enter(job);
939     }
940 }
941 
942 void job_user_cancel(Job *job, bool force, Error **errp)
943 {
944     if (job_apply_verb(job, JOB_VERB_CANCEL, errp)) {
945         return;
946     }
947     job_cancel(job, force);
948 }
949 
950 /* A wrapper around job_cancel() taking an Error ** parameter so it may be
951  * used with job_finish_sync() without the need for (rather nasty) function
952  * pointer casts there. */
953 static void job_cancel_err(Job *job, Error **errp)
954 {
955     job_cancel(job, false);
956 }
957 
958 int job_cancel_sync(Job *job)
959 {
960     return job_finish_sync(job, &job_cancel_err, NULL);
961 }
962 
963 void job_cancel_sync_all(void)
964 {
965     Job *job;
966     AioContext *aio_context;
967 
968     while ((job = job_next(NULL))) {
969         aio_context = job->aio_context;
970         aio_context_acquire(aio_context);
971         job_cancel_sync(job);
972         aio_context_release(aio_context);
973     }
974 }
975 
976 int job_complete_sync(Job *job, Error **errp)
977 {
978     return job_finish_sync(job, job_complete, errp);
979 }
980 
981 void job_complete(Job *job, Error **errp)
982 {
983     /* Should not be reachable via external interface for internal jobs */
984     assert(job->id);
985     if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) {
986         return;
987     }
988     if (job->pause_count || job_is_cancelled(job) || !job->driver->complete) {
989         error_setg(errp, "The active block job '%s' cannot be completed",
990                    job->id);
991         return;
992     }
993 
994     job->driver->complete(job, errp);
995 }
996 
997 int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)
998 {
999     Error *local_err = NULL;
1000     int ret;
1001 
1002     job_ref(job);
1003 
1004     if (finish) {
1005         finish(job, &local_err);
1006     }
1007     if (local_err) {
1008         error_propagate(errp, local_err);
1009         job_unref(job);
1010         return -EBUSY;
1011     }
1012 
1013     AIO_WAIT_WHILE(job->aio_context,
1014                    (job_enter(job), !job_is_completed(job)));
1015 
1016     ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
1017     job_unref(job);
1018     return ret;
1019 }
1020