Xen devel - Nov 2009 - [PATCH 14/14]: libxenlight, checks before device deletion and addition

Proper existential checks before adding or deleting a
device, i.e. return error if:

- Adding a device to a non-existent domain
- Adding a device twice
- Deleting a non-existent device
- Deleting a device from a non-existent domain

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.com>




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On Mon, Nov 30, 2009 at 07:18:18PM +0000, Andres Lagar-Cavilla
wrote:
> Proper existential checks before adding or deleting a
> device, i.e. return error if:
> 
> - Adding a device to a non-existent domain
> - Adding a device twice
> - Deleting a non-existent device
> - Deleting a device from a non-existent domain
> 
> Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.com>

you should not check the non-existency of a domain. this is pointless
since just after you check the domain might have gone away. also you might
think of a mode where you populate the xenstore tree before creating the domain
.. nobody does that, but I don''t think there''s any major
stopper to do that or
that it would be a bad idea either.

Same reason that should it not check for device existency outside of the
transaction, otherwise someome might have added it in the meantime.

PS: please don''t call libxl_free, that''s really unnecessary at
this stage,
until we sort memory handling completly. (there''s a "GC" for
now)

-- 
Vincent

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Agreed in that it is a weak check being non-transactional. But some 
check should be there, shouldn''t it? Just throwing it out there. The 
other checks are kosher I assume?
Andres
Vincent Hanquez wrote:
> On Mon, Nov 30, 2009 at 07:18:18PM +0000, Andres Lagar-Cavilla wrote:
>   
>> Proper existential checks before adding or deleting a
>> device, i.e. return error if:
>>
>> - Adding a device to a non-existent domain
>> - Adding a device twice
>> - Deleting a non-existent device
>> - Deleting a device from a non-existent domain
>>
>> Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.com>
>>     
>
>
> you should not check the non-existency of a domain. this is pointless
> since just after you check the domain might have gone away. also you might
> think of a mode where you populate the xenstore tree before creating the
domain
> .. nobody does that, but I don''t think there''s any major
stopper to do that or
> that it would be a bad idea either.
>
> Same reason that should it not check for device existency outside of the
> transaction, otherwise someome might have added it in the meantime.
>
> PS: please don''t call libxl_free, that''s really
unnecessary at this stage,
> until we sort memory handling completly. (there''s a "GC"
for now)
>
>   

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