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[Qemu-block] [PATCH 04/14] job: Use AIO_WAIT_WHILE() in job_finish_sync(
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PATCH 04/14] job: Use AIO_WAIT_WHILE() in job_finish_sync() |
Date: |
Fri, 7 Sep 2018 18:15:10 +0200 |
job_finish_sync() needs to release the AioContext lock of the job before
calling aio_poll(). Otherwise, callbacks called by aio_poll() would
possibly take the lock a second time and run into a deadlock with a
nested AIO_WAIT_WHILE() call.
Also, job_drain() without aio_poll() isn't necessarily enough to make
progress on a job, it could depend on bottom halves to be executed.
Combine both open-coded while loops into a single AIO_WAIT_WHILE() call
that solves both of these problems.
Signed-off-by: Kevin Wolf <address@hidden>
---
job.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/job.c b/job.c
index 9ad0b7476a..8480eda188 100644
--- a/job.c
+++ b/job.c
@@ -29,6 +29,7 @@
#include "qemu/job.h"
#include "qemu/id.h"
#include "qemu/main-loop.h"
+#include "block/aio-wait.h"
#include "trace-root.h"
#include "qapi/qapi-events-job.h"
@@ -998,6 +999,7 @@ void job_defer_to_main_loop(Job *job, JobDeferToMainLoopFn
*fn, void *opaque)
int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error
**errp)
{
Error *local_err = NULL;
+ AioWait dummy_wait = {};
int ret;
job_ref(job);
@@ -1010,14 +1012,10 @@ int job_finish_sync(Job *job, void (*finish)(Job *,
Error **errp), Error **errp)
job_unref(job);
return -EBUSY;
}
- /* job_drain calls job_enter, and it should be enough to induce progress
- * until the job completes or moves to the main thread. */
- while (!job->deferred_to_main_loop && !job_is_completed(job)) {
- job_drain(job);
- }
- while (!job_is_completed(job)) {
- aio_poll(qemu_get_aio_context(), true);
- }
+
+ AIO_WAIT_WHILE(&dummy_wait, job->aio_context,
+ (job_drain(job), !job_is_completed(job)));
+
ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
job_unref(job);
return ret;
--
2.13.6
- [Qemu-block] [PATCH 00/14] Fix some jobs/drain/aio_poll related hangs, Kevin Wolf, 2018/09/07
- [Qemu-block] [PATCH 03/14] test-blockjob: Acquire AioContext around job_finish_sync(), Kevin Wolf, 2018/09/07
- [Qemu-block] [PATCH 01/14] blockjob: Wake up BDS when job becomes idle, Kevin Wolf, 2018/09/07
- [Qemu-block] [PATCH 04/14] job: Use AIO_WAIT_WHILE() in job_finish_sync(),
Kevin Wolf <=
- [Qemu-block] [PATCH 02/14] test-bdrv-drain: Drain with block jobs in an I/O thread, Kevin Wolf, 2018/09/07
- [Qemu-block] [PATCH 07/14] aio-wait: Increase num_waiters even in home thread, Kevin Wolf, 2018/09/07
- [Qemu-block] [PATCH 05/14] test-bdrv-drain: Test AIO_WAIT_WHILE() in completion callback, Kevin Wolf, 2018/09/07
- [Qemu-block] [PATCH 06/14] block: Add missing locking in bdrv_co_drain_bh_cb(), Kevin Wolf, 2018/09/07