| Message ID | 1454379144-29807-1-git-send-email-famz@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Feb 02, 2016 at 10:12:24AM +0800, Fam Zheng wrote: > With a mirror job running on a virtio-blk dataplane disk, sending "q" to > HMP will cause a dead loop in block_job_finish_sync. > > This is because the aio_poll() only processes the AIO context of bs > which has no more work to do, while the main loop BH that is scheduled > for setting the job->completed flag is never processed. > > Fix this by adding a flag in BlockJob structure, to track which context > to poll for the block job to make progress. Its value is set to true > when block_job_coroutine_complete() is called, and is checked in > block_job_finish_sync to determine which context to poll. > > Suggested-by: Stefan Hajnoczi <stefanha@redhat.com> > Signed-off-by: Fam Zheng <famz@redhat.com> > --- > blockjob.c | 6 +++++- > include/block/blockjob.h | 5 +++++ > 2 files changed, 10 insertions(+), 1 deletion(-) Thanks, applied to my block tree: https://github.com/stefanha/qemu/commits/block Stefan
diff --git a/blockjob.c b/blockjob.c index 80adb9d..b15df93 100644 --- a/blockjob.c +++ b/blockjob.c @@ -304,7 +304,9 @@ static int block_job_finish_sync(BlockJob *job, return -EBUSY; } while (!job->completed) { - aio_poll(bdrv_get_aio_context(bs), true); + aio_poll(job->deferred_to_main_loop ? qemu_get_aio_context() : + bdrv_get_aio_context(bs), + true); } ret = (job->cancelled && job->ret == 0) ? -ECANCELED : job->ret; block_job_unref(job); @@ -478,6 +480,7 @@ static void block_job_defer_to_main_loop_bh(void *opaque) aio_context = bdrv_get_aio_context(data->job->bs); aio_context_acquire(aio_context); + data->job->deferred_to_main_loop = false; data->fn(data->job, data->opaque); aio_context_release(aio_context); @@ -497,6 +500,7 @@ void block_job_defer_to_main_loop(BlockJob *job, data->aio_context = bdrv_get_aio_context(job->bs); data->fn = fn; data->opaque = opaque; + job->deferred_to_main_loop = true; qemu_bh_schedule(data->bh); } diff --git a/include/block/blockjob.h b/include/block/blockjob.h index d84ccd8..8bedc49 100644 --- a/include/block/blockjob.h +++ b/include/block/blockjob.h @@ -130,6 +130,11 @@ struct BlockJob { */ bool ready; + /** + * Set to true when the job has deferred work to the main loop. + */ + bool deferred_to_main_loop; + /** Status that is published by the query-block-jobs QMP API */ BlockDeviceIoStatus iostatus;
With a mirror job running on a virtio-blk dataplane disk, sending "q" to HMP will cause a dead loop in block_job_finish_sync. This is because the aio_poll() only processes the AIO context of bs which has no more work to do, while the main loop BH that is scheduled for setting the job->completed flag is never processed. Fix this by adding a flag in BlockJob structure, to track which context to poll for the block job to make progress. Its value is set to true when block_job_coroutine_complete() is called, and is checked in block_job_finish_sync to determine which context to poll. Suggested-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Fam Zheng <famz@redhat.com> --- blockjob.c | 6 +++++- include/block/blockjob.h | 5 +++++ 2 files changed, 10 insertions(+), 1 deletion(-)