From: Fam Zheng <famz@redhat.com>
To: mreitz@redhat.com, kwolf@redhat.com, jcody@redhat.com
Cc: Paolo Bonzini <pbonzini@redhat.com>,
stefanha@redhat.com, qemu-devel@nongnu.org,
qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 5/5] block: keep AioContext pointer in BlockBackend
Date: Fri, 30 Sep 2016 13:22:58 +0800 [thread overview]
Message-ID: <20160930052258.GA2564@lemon> (raw)
In-Reply-To: <3a5afa67-e580-cd20-6d19-9c9071bf55a0@redhat.com>
On Thu, 09/29 09:47, Paolo Bonzini wrote:
>
>
> On 29/09/2016 05:05, Fam Zheng wrote:
> > > So whether we can move a certain BB from some context to another depends
> > > on what the frontend supports, I don't think there is a generic answer
> > > we can implement here in the generic BB code. NBD for instance allows
> > > any movement; but devices probably only allow movements they have
> > > initiated themselves (e.g. dataplane will allow exactly what you
> > > describe here with that assertion, and any other device will probably
> > > not allow anything but the main loop).
> >
> > Indeed, you make me think this should be an op blocker (that applies on whole
> > graph).
>
> The concept of a BDS or BB's AioContext is going to disappear sooner or
> later, take this into account to decide how much effort to put into
> fixing this.
Taking one step back, the whole thing is so broken considering the node
reference. Currently, even this is possible:
-drive file=null-co://,if=virtio,id=d0 \
-drive file.file=d0,driver=raw,file.driver=raw,if=virtio
AioContext is actually a factor to make it worse. Maybe we should instead think
about some generic protection mechanism? Is this in the scope of new op
blocker?
Fam
prev parent reply other threads:[~2016-09-30 5:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 6:37 [Qemu-devel] [PATCH v2 0/5] block: keep AioContext pointer in BlockBackend Fam Zheng
2016-09-27 6:37 ` [Qemu-devel] [PATCH v2 1/5] blockdev-mirror: Sanity check before moving target_bs AioContext Fam Zheng
2016-09-28 16:37 ` Max Reitz
2016-09-29 3:14 ` Fam Zheng
2016-09-27 6:37 ` [Qemu-devel] [PATCH v2 2/5] blockdev: Move BDS AioContext before inserting to BB Fam Zheng
2016-09-28 17:09 ` Max Reitz
2016-09-27 6:37 ` [Qemu-devel] [PATCH v2 3/5] block: Introduce and make use of blk_new_with_root Fam Zheng
2016-09-28 17:21 ` Max Reitz
2016-09-27 6:37 ` [Qemu-devel] [PATCH v2 4/5] migration: Set correct AioContext to BlockBackend Fam Zheng
2016-09-28 17:26 ` Max Reitz
2016-09-27 6:37 ` [Qemu-devel] [PATCH v2 5/5] block: keep AioContext pointer in BlockBackend Fam Zheng
2016-09-28 17:47 ` Max Reitz
2016-09-29 3:05 ` Fam Zheng
2016-09-29 7:47 ` Paolo Bonzini
2016-09-30 5:22 ` Fam Zheng [this message]
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