Re: [Qemu-devel] [PATCH 1/5] qom: adopt rwlock to protect accessing dev from removing it

[liu ping fan]

On Wed, Jul 25, 2012 at 5:08 PM, Paolo Bonzini <address@hidden> wrote:
> Il 25/07/2012 05:31, Liu Ping Fan ha scritto:
>> From: Liu Ping Fan <address@hidden>
>>
>> rwlock:
>>   qemu_device_tree_mutex
>>
>> rd side:
>>   --device_del(destruction of device will be postphoned until unplug
>>     ack from guest),
>>   --pci hot-unplug
>>   --iteration (qdev_reset_all)
>>
>> wr side:
>>   --device_add
>>
>> Signed-off-by: Liu Ping Fan <address@hidden>
>> ---
>>  hw/pci-hotplug.c  |    4 ++++
>>  hw/qdev-monitor.c |   17 ++++++++++++++++-
>>  hw/qdev.c         |    2 ++
>>  3 files changed, 22 insertions(+), 1 deletions(-)
>>
>> diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
>> index e7fb780..b3b88c1 100644
>> --- a/hw/pci-hotplug.c
>> +++ b/hw/pci-hotplug.c
>> @@ -265,9 +265,11 @@ static int pci_device_hot_remove(Monitor *mon, const 
>> char *pci_addr)
>>          return -1;
>>      }
>>
>> +    qemu_rwlock_rdlock_devtree();
>
> This is not defined anywhere, is a piece missing in the patch?
>
Oh, yes, I miss the patch.  In that patch, these rwlock are just place holder.
I see there is already try to implement rwlock for qemu.
    http://lists.gnu.org/archive/html/qemu-devel/2011-10/msg00192.html
and is it the time for introduce rwlock for qemu?

Thanks,
pingfan


> Paolo
>