Re: [Qemu-devel] [PATCH v2] job: Fix nested aio_poll() hanging in job_txn_apply

[Kevin Wolf <kwolf@redhat.com>]

Am 24.08.2018 um 04:43 hat Fam Zheng geschrieben:
> All callers have acquired ctx already. Doing that again results in
> aio_poll() hang. This fixes the problem that a BDRV_POLL_WHILE() in the
> callback cannot make progress because ctx is recursively locked, for
> example, when drive-backup finishes.
> 
> There are two callers of job_finalize():
> 
>     fam@lemon:~/work/qemu [master]$ git grep -w -A1 '^\s*job_finalize'
>     blockdev.c:    job_finalize(&job->job, errp);
>     blockdev.c-    aio_context_release(aio_context);
>     --
>     job-qmp.c:    job_finalize(job, errp);
>     job-qmp.c-    aio_context_release(aio_context);
>     --
>     tests/test-blockjob.c:    job_finalize(&job->job, &error_abort);
>     tests/test-blockjob.c-    assert(job->job.status == JOB_STATUS_CONCLUDED);
> 
> Ignoring the test, it's easy to see both callers to job_finalize (and
> job_do_finalize) have acquired the context.
> 
> Cc: qemu-stable@nongnu.org
> Reported-by: Gu Nini <ngu@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>

Thanks, applied to the block branch.

Kevin