From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46726) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g0R79-0002EL-Mm for qemu-devel@nongnu.org; Thu, 13 Sep 2018 08:53:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g0R78-0001pu-Ss for qemu-devel@nongnu.org; Thu, 13 Sep 2018 08:52:55 -0400 From: Kevin Wolf Date: Thu, 13 Sep 2018 14:52:06 +0200 Message-Id: <20180913125217.23173-7-kwolf@redhat.com> In-Reply-To: <20180913125217.23173-1-kwolf@redhat.com> References: <20180913125217.23173-1-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH v2 06/17] job: Use AIO_WAIT_WHILE() in job_finish_sync() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com, famz@redhat.com, pbonzini@redhat.com, slp@redhat.com, jsnow@redhat.com, qemu-devel@nongnu.org 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 Reviewed-by: Fam Zheng --- 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