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[Qemu-block] [PATCH v2 06/17] job: Use AIO_WAIT_WHILE() in job_finish_sy
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PATCH v2 06/17] job: Use AIO_WAIT_WHILE() in job_finish_sync() |
Date: |
Thu, 13 Sep 2018 14:52:06 +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>
Reviewed-by: Fam Zheng <address@hidden>
---
job.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/job.c b/job.c
index 48a767c102..fa74558ba0 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"
@@ -962,6 +963,7 @@ void job_complete(Job *job, Error **errp)
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);
@@ -974,14 +976,10 @@ 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
- Re: [Qemu-block] [PATCH v2 01/17] job: Fix missing locking due to mismerge, (continued)
- [Qemu-block] [PATCH v2 04/17] test-bdrv-drain: Drain with block jobs in an I/O thread, Kevin Wolf, 2018/09/13
- [Qemu-block] [PATCH v2 05/17] test-blockjob: Acquire AioContext around job_cancel_sync(), Kevin Wolf, 2018/09/13
- [Qemu-block] [PATCH v2 06/17] job: Use AIO_WAIT_WHILE() in job_finish_sync(),
Kevin Wolf <=
- [Qemu-block] [PATCH v2 08/17] block: Add missing locking in bdrv_co_drain_bh_cb(), Kevin Wolf, 2018/09/13
- [Qemu-block] [PATCH v2 09/17] block-backend: Add .drained_poll callback, Kevin Wolf, 2018/09/13
- [Qemu-block] [PATCH v2 07/17] test-bdrv-drain: Test AIO_WAIT_WHILE() in completion callback, Kevin Wolf, 2018/09/13