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Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug |
Date: |
Tue, 25 Jun 2013 09:53:52 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 25/06/2013 08:32, liu ping fan ha scritto:
> On Tue, Jun 25, 2013 at 2:24 PM, Paolo Bonzini <address@hidden> wrote:
>> Il 25/06/2013 19:38, Liu Ping Fan ha scritto:
>>> This series relies on refcnt of object used by bh callback to run against
>>> unplug.
>>>
>>> Open issue:
>>> Another choice may be rcu, but I think some issues are hard to resolve.
>>> Using rcu, we have two choice:
>>> when holding object refcnt, call qemu_bh_delete(); then after grace
>>> period, we can release.
>>> Or making qemu_bh_delete() sync in the path of DeviceState's finalization.
>>
>> What do you mean exactly? qemu_bh_delete() is async, but it operates on
>> dynamically-allocated memory.
>>
> Before DeviceState is freed, we should make sure the bh is delete, and
> not related bh is in fly.
The bh need not be deleted. It just needs to be not-scheduled (easy,
qemu_bh_delete does that) and not running.
The latter part could be the hard one in a multi-threaded context, but I
think it's up to the device to ensure it. It doesn't _have_ to be hard.
For example, joining the data-plane thread would do that as well.
Paolo
>> Paolo
>>
>>> but currently, the callers of qemu_bh_delete() can not satisfy any of the
>>> two condition.
>>
- [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, Liu Ping Fan, 2013/06/25
- [Qemu-devel] [PATCH 1/3] QEMUBH: introduce canceled member for bh, Liu Ping Fan, 2013/06/25
- [Qemu-devel] [PATCH 2/3] QEMUBH: pin bh's referring object while scheduling, Liu Ping Fan, 2013/06/25
- [Qemu-devel] [PATCH 3/3] virtio-net: set referred object for virtio net's bh, Liu Ping Fan, 2013/06/25
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, Paolo Bonzini, 2013/06/25
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, liu ping fan, 2013/06/25
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, liu ping fan, 2013/06/25
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, Paolo Bonzini, 2013/06/26
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, liu ping fan, 2013/06/26
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, Paolo Bonzini, 2013/06/26
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, liu ping fan, 2013/06/26
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, Paolo Bonzini, 2013/06/26
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, liu ping fan, 2013/06/26
- Re: [Qemu-devel] [PATCH 0/3] make bh safe with hot-unplug, Paolo Bonzini, 2013/06/27