Re: [Qemu-devel] [PATCH v2 11/17] block-backend: Decrease in_flight only after callback

[Kevin Wolf]

Am 14.09.2018 um 19:38 hat Paolo Bonzini geschrieben:
> On 14/09/2018 19:14, Kevin Wolf wrote:
> >> As you mention, you could have a nested aio_poll() in the main thread,
> >> for example invoked from a bottom half, but in that case I'd rather
> >> track the caller that is creating the bottom half and see if it lacks a
> >> bdrv_ref/bdrv_unref (or perhaps it's even higher in the tree that is
> >> missing).
> > I went back to the commit where I first added the patch (it already
> > contained the ref/unref pair) and tried if I could reproduce a bug with
> > the pair removed. I couldn't.
> > 
> > I'm starting to think that maybe I was just overly cautious with the
> > ref/unref. I may have confused the nested aio_poll() crash with a
> > different situation. I've dealt with so many crashes and hangs while
> > working on this series that it's quite possible.
> 
> Are you going to drop the patch hen?

I think I can drop the ref/unref pair, but not the whole patch (whose
main point is reordering dec_in_flight vs. the AIO callback).

Kevin