qemu-e2k/job-qmp.c
Stefan Reiter b660a84bbb job: take each job's lock individually in job_txn_apply
All callers of job_txn_apply hold a single job's lock, but different
jobs within a transaction can have different contexts, thus we need to
lock each one individually before applying the callback function.

Similar to job_completed_txn_abort this also requires releasing the
caller's context before and reacquiring it after to avoid recursive
locks which might break AIO_WAIT_WHILE in the callback. This is safe, since
existing code would already have to take this into account, lest
job_completed_txn_abort might have broken.

This also brings to light a different issue: When a callback function in
job_txn_apply moves it's job to a different AIO context, callers will
try to release the wrong lock (now that we re-acquire the lock
correctly, previously it would just continue with the old lock, leaving
the job unlocked for the rest of the return path). Fix this by not caching
the job's context.

This is only necessary for qmp_block_job_finalize, qmp_job_finalize and
job_exit, since everyone else calls through job_exit.

One test needed adapting, since it calls job_finalize directly, so it
manually needs to acquire the correct context.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Message-Id: <20200407115651.69472-2-s.reiter@proxmox.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-07 14:34:47 +02:00

193 lines
4.8 KiB
C

/*
* QMP interface for background jobs
*
* Copyright (c) 2011 IBM Corp.
* Copyright (c) 2012, 2018 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu/job.h"
#include "qapi/qapi-commands-job.h"
#include "qapi/error.h"
#include "trace-root.h"
/* Get a job using its ID and acquire its AioContext */
static Job *find_job(const char *id, AioContext **aio_context, Error **errp)
{
Job *job;
*aio_context = NULL;
job = job_get(id);
if (!job) {
error_setg(errp, "Job not found");
return NULL;
}
*aio_context = job->aio_context;
aio_context_acquire(*aio_context);
return job;
}
void qmp_job_cancel(const char *id, Error **errp)
{
AioContext *aio_context;
Job *job = find_job(id, &aio_context, errp);
if (!job) {
return;
}
trace_qmp_job_cancel(job);
job_user_cancel(job, true, errp);
aio_context_release(aio_context);
}
void qmp_job_pause(const char *id, Error **errp)
{
AioContext *aio_context;
Job *job = find_job(id, &aio_context, errp);
if (!job) {
return;
}
trace_qmp_job_pause(job);
job_user_pause(job, errp);
aio_context_release(aio_context);
}
void qmp_job_resume(const char *id, Error **errp)
{
AioContext *aio_context;
Job *job = find_job(id, &aio_context, errp);
if (!job) {
return;
}
trace_qmp_job_resume(job);
job_user_resume(job, errp);
aio_context_release(aio_context);
}
void qmp_job_complete(const char *id, Error **errp)
{
AioContext *aio_context;
Job *job = find_job(id, &aio_context, errp);
if (!job) {
return;
}
trace_qmp_job_complete(job);
job_complete(job, errp);
aio_context_release(aio_context);
}
void qmp_job_finalize(const char *id, Error **errp)
{
AioContext *aio_context;
Job *job = find_job(id, &aio_context, errp);
if (!job) {
return;
}
trace_qmp_job_finalize(job);
job_ref(job);
job_finalize(job, errp);
/*
* Job's context might have changed via job_finalize (and job_txn_apply
* automatically acquires the new one), so make sure we release the correct
* one.
*/
aio_context = job->aio_context;
job_unref(job);
aio_context_release(aio_context);
}
void qmp_job_dismiss(const char *id, Error **errp)
{
AioContext *aio_context;
Job *job = find_job(id, &aio_context, errp);
if (!job) {
return;
}
trace_qmp_job_dismiss(job);
job_dismiss(&job, errp);
aio_context_release(aio_context);
}
static JobInfo *job_query_single(Job *job, Error **errp)
{
JobInfo *info;
assert(!job_is_internal(job));
info = g_new(JobInfo, 1);
*info = (JobInfo) {
.id = g_strdup(job->id),
.type = job_type(job),
.status = job->status,
.current_progress = job->progress.current,
.total_progress = job->progress.total,
.has_error = !!job->err,
.error = job->err ? \
g_strdup(error_get_pretty(job->err)) : NULL,
};
return info;
}
JobInfoList *qmp_query_jobs(Error **errp)
{
JobInfoList *head = NULL, **p_next = &head;
Job *job;
for (job = job_next(NULL); job; job = job_next(job)) {
JobInfoList *elem;
AioContext *aio_context;
if (job_is_internal(job)) {
continue;
}
elem = g_new0(JobInfoList, 1);
aio_context = job->aio_context;
aio_context_acquire(aio_context);
elem->value = job_query_single(job, errp);
aio_context_release(aio_context);
if (!elem->value) {
g_free(elem);
qapi_free_JobInfoList(head);
return NULL;
}
*p_next = elem;
p_next = &elem->next;
}
return head;
}