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block: remove AioContext locking

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This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.

There isn't a clean way to split this patch and the reviewers are likely
the same group of people, so I decided to do it in one patch.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-ID: <20231205182011.1976568-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2023-12-05 13:20:03 -05:00 • committed by Kevin Wolf
parent 6bc30f1949
commit b49f4755c7
41 changed files with 104 additions and 1169 deletions
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137
tests/unit/test-blockjob.c
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@ -228,7 +228,6 @@ static void cancel_common(CancelJob *s)
BlockJob *job = &s->common;
BlockBackend *blk = s->blk;
JobStatus sts = job->job.status;
AioContext *ctx = job->job.aio_context;
job_cancel_sync(&job->job, true);
WITH_JOB_LOCK_GUARD() {
@ -240,9 +239,7 @@ static void cancel_common(CancelJob *s)
job_unref_locked(&job->job);
}
aio_context_acquire(ctx);
destroy_blk(blk);
aio_context_release(ctx);
}
@ -391,132 +388,6 @@ static void test_cancel_concluded(void)
cancel_common(s);
}
/* (See test_yielding_driver for the job description) */
typedef struct YieldingJob {
BlockJob common;
bool should_complete;
} YieldingJob;
static void yielding_job_complete(Job *job, Error **errp)
{
YieldingJob *s = container_of(job, YieldingJob, common.job);
s->should_complete = true;
job_enter(job);
}
static int coroutine_fn yielding_job_run(Job *job, Error **errp)
{
YieldingJob *s = container_of(job, YieldingJob, common.job);
job_transition_to_ready(job);
while (!s->should_complete) {
job_yield(job);
}
return 0;
}
/*
* This job transitions immediately to the READY state, and then
* yields until it is to complete.
*/
static const BlockJobDriver test_yielding_driver = {
.job_driver = {
.instance_size = sizeof(YieldingJob),
.free = block_job_free,
.user_resume = block_job_user_resume,
.run = yielding_job_run,
.complete = yielding_job_complete,
},
};
/*
* Test that job_complete_locked() works even on jobs that are in a paused
* state (i.e., STANDBY).
*
* To do this, run YieldingJob in an IO thread, get it into the READY
* state, then have a drained section. Before ending the section,
* acquire the context so the job will not be entered and will thus
* remain on STANDBY.
*
* job_complete_locked() should still work without error.
*
* Note that on the QMP interface, it is impossible to lock an IO
* thread before a drained section ends. In practice, the
* bdrv_drain_all_end() and the aio_context_acquire() will be
* reversed. However, that makes for worse reproducibility here:
* Sometimes, the job would no longer be in STANDBY then but already
* be started. We cannot prevent that, because the IO thread runs
* concurrently. We can only prevent it by taking the lock before
* ending the drained section, so we do that.
*
* (You can reverse the order of operations and most of the time the
* test will pass, but sometimes the assert(status == STANDBY) will
* fail.)
*/
static void test_complete_in_standby(void)
{
BlockBackend *blk;
IOThread *iothread;
AioContext *ctx;
Job *job;
BlockJob *bjob;
/* Create a test drive, move it to an IO thread */
blk = create_blk(NULL);
iothread = iothread_new();
ctx = iothread_get_aio_context(iothread);
blk_set_aio_context(blk, ctx, &error_abort);
/* Create our test job */
bjob = mk_job(blk, "job", &test_yielding_driver, true,
JOB_MANUAL_FINALIZE | JOB_MANUAL_DISMISS);
job = &bjob->job;
assert_job_status_is(job, JOB_STATUS_CREATED);
/* Wait for the job to become READY */
job_start(job);
/*
* Here we are waiting for the status to change, so don't bother
* protecting the read every time.
*/
AIO_WAIT_WHILE_UNLOCKED(ctx, job->status != JOB_STATUS_READY);
/* Begin the drained section, pausing the job */
bdrv_drain_all_begin();
assert_job_status_is(job, JOB_STATUS_STANDBY);
/* Lock the IO thread to prevent the job from being run */
aio_context_acquire(ctx);
/* This will schedule the job to resume it */
bdrv_drain_all_end();
aio_context_release(ctx);
WITH_JOB_LOCK_GUARD() {
/* But the job cannot run, so it will remain on standby */
assert(job->status == JOB_STATUS_STANDBY);
/* Even though the job is on standby, this should work */
job_complete_locked(job, &error_abort);
/* The test is done now, clean up. */
job_finish_sync_locked(job, NULL, &error_abort);
assert(job->status == JOB_STATUS_PENDING);
job_finalize_locked(job, &error_abort);
assert(job->status == JOB_STATUS_CONCLUDED);
job_dismiss_locked(&job, &error_abort);
}
aio_context_acquire(ctx);
destroy_blk(blk);
aio_context_release(ctx);
iothread_join(iothread);
}
int main(int argc, char **argv)
{
qemu_init_main_loop(&error_abort);
@ -531,13 +402,5 @@ int main(int argc, char **argv)
g_test_add_func("/blockjob/cancel/standby", test_cancel_standby);
g_test_add_func("/blockjob/cancel/pending", test_cancel_pending);
g_test_add_func("/blockjob/cancel/concluded", test_cancel_concluded);
/*
* This test is flaky and sometimes fails in CI and otherwise:
* don't run unless user opts in via environment variable.
*/
if (getenv("QEMU_TEST_FLAKY_TESTS")) {
g_test_add_func("/blockjob/complete_in_standby", test_complete_in_standby);
}
return g_test_run();
}