Re: [Qemu-devel] [PATCH v2 1/2] virtio-blk: Release s->rq queue at system_reset

[Fam Zheng <famz@redhat.com>]

On Tue, 08/02 13:00, Paolo Bonzini wrote:
> 
> > I'd prefer if Paolo's remark (about blk_drain()'s ability to produce
> > more failed requests, stashed in s->rq) were captured in either the
> > commit message, or in a code comment. Something like:
> > 
> >   /* We drop queued requests after blk_drain() because blk_drain()
> >    * itself can produce them. */
> 
> It's also (perhaps especially) because blk_drain() can consume them.  Fam's
> patch to do blk_drain() first would cause a double-free.

That "consume" part is what I don't understand.

Shouldn't blk_drain() only process submitted requests (and further requests
they dequeue indirectly), while s->rq only contains failed requests. They don't
look overlap, because I suppose failed requests are only going to be processed
by run state change.

What am I missing?

Fam