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Date: Sun, 15 Jun 2008 09:25:35 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] Merge NBD client/server int qemu-nbd
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To: qemu-devel@nongnu.org

Laurent Vivier wrote:
> Le samedi 14 juin 2008 à 12:35 -0700, Avi Kivity a écrit :
>   
>> Laurent Vivier wrote:
>>
>>   
>>
>>     
>>>> It is udev that creates the devices, based on events it receives from 
>>>> the kernel.  Calling udevsettle after the kernel instructs udev to 
>>>> create the device files will wait until they are actually created.
>>>>     
>>>>         
>>> Yes, I agree but the kernel events are generated by the open(), so I
>>> think I can't use this to know if I can use open(). 
>>>
>>> I've used udevmonitor to see what happen:
>>> - without open() -> no events
>>> - whith open() whithout sleep() -> no events
>>> -> open() + sleep() -> events generated by the partition creation.
>>>
>>> So, what do I miss ?
>>>   
>>>       
>> For this, it seems like sleep() generates the events, which is a little 
>> unlikely.  I suggest re-checking this.
>>     
>
> re-checked, no events with sleep() only.
>
> events generated with sleep() + open() are:
>   

I imagine the sleep() is causing another task to be scheduled (probably 
the server) which is what ends up generating the event.

Regards,

Anthony Liguori