Re: [Qemu-devel] [RFC PATCH 0/5] Fix some jobs/drain/aio_poll related hangs

[Fam Zheng <famz@redhat.com>]

On Fri, 08/17 19:02, Kevin Wolf wrote:
> I'm running out of time and will be offline for the next two weeks, so
> I'm just sending out what I have right now. This is probably not ready
> to be merged yet, but if need be, someone else can pick it up. Otherwise
> I'll do that myself when I return.

I'll try take a look at these. But I'll start from

https://bugzilla.redhat.com/show_bug.cgi?id=1609137

> 
> This is related to the following bug reports:
> https://bugzilla.redhat.com/show_bug.cgi?id=1614623
> https://bugzilla.redhat.com/show_bug.cgi?id=1601212
> 
> Essentially it tries to fix a few deadlocks into which we run when
> running two commit jobs (probably just one example for problematic
> scenarios) on nodes that are in a non-mainloop AioContext (i.e. with
> dataplane).
> 
> Obviously, besides verifying that the code changes are actually correct
> as they are, we also want to add some test cases for this. I suppose
> test-bdrv-drain should test for the individual bugs, and a qemu-iotests
> case could try the higher level scenario of multiple commit jobs with
> dataplane.

The test coverage of dataplane is terribly low. Let's think about adding
variants to existing iotests around block jobs at least.

Fam

> 
> Kevin Wolf (5):
>   blockjob: Wake up BDS when job becomes idle
>   tests: Acquire AioContext around job_finish_sync()
>   job: Drop AioContext lock around aio_poll()
>   block: Drop AioContext lock in bdrv_drain_poll_top_level()
>   [WIP] Lock AioContext in bdrv_co_drain_bh_cb()
> 
>  include/block/blockjob.h | 13 +++++++++++++
>  include/qemu/job.h       |  9 +++++++++
>  block/io.c               | 31 ++++++++++++++++++++++++++++++-
>  blockjob.c               | 18 ++++++++++++++++++
>  job.c                    | 10 ++++++++++
>  tests/test-bdrv-drain.c  |  6 ++++++
>  tests/test-blockjob.c    |  6 ++++++
>  7 files changed, 92 insertions(+), 1 deletion(-)
> 
> -- 
> 2.13.6
>