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Re: [Qemu-block] [PATCH 2/2] blockjob: Fix hang in block_job_finish_sync
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [PATCH 2/2] blockjob: Fix hang in block_job_finish_sync |
Date: |
Thu, 28 Jan 2016 18:57:51 +0800 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, 01/28 10:10, Paolo Bonzini wrote:
>
>
> On 28/01/2016 08:02, Fam Zheng wrote:
> >
> > 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 "ctx" pointer in BlockJob structure, to track which
> > context to poll for the block job to make progress. Its value is set to
> > the BDS context at block job creation, until
> > block_job_coroutine_complete() is called by the block job coroutine.
> > After that point, the block job's work is deferred to main loop BH.
> >
> > Signed-off-by: Fam Zheng <address@hidden>
> > ---
> > blockjob.c | 4 +++-
> > include/block/blockjob.h | 2 ++
> > 2 files changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/blockjob.c b/blockjob.c
> > index 4b16720..4ea1ce0 100644
> > --- a/blockjob.c
> > +++ b/blockjob.c
> > @@ -74,6 +74,7 @@ void *block_job_create(const BlockJobDriver *driver,
> > BlockDriverState *bs,
> > job->opaque = opaque;
> > job->busy = true;
> > job->refcnt = 1;
> > + job->ctx = bdrv_get_aio_context(bs);
>
> Can the context change if dataplane is started/stopped in the middle of
> a job? (For example if you start migration). Perhaps job->ctx == NULL
> could mean "use bdrv_get_aio_context(bs)".
Yes, that's a good idea.
Fam