Re: [PATCH] crypto: AF_ALG AIO - lock context IV

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On Thu, Feb 1, 2018 at 12:04 PM, Stephan Mueller <smueller@xxxxxxxxxx> wrote:
> Am Donnerstag, 1. Februar 2018, 10:35:07 CET schrieb Gilad Ben-Yossef:
>
> Hi Gilad,
>
>> >
>> > Which works well for the sort of optimization I did and for hardware that
>> > can do iv dependency tracking itself. If hardware dependency tracking was
>> > avilable, you would be able to queue up requests with a chained IV
>> > without taking any special precautions at all. The hardware would
>> > handle the IV update dependencies.
>> >
>> > So in conclusion, Stephan's approach should work and give us a nice
>> > small patch suitable for stable inclusion.
>> >
>> > However, if people know that their setup overhead can be put in parallel
>> > with previous requests (even when the IV is not yet updated) then they
>> > will
>> > probably want to do something inside their own driver and set the flag
>> > that Stephan is proposing adding to bypass the mutex approach.
>>
>> The patches from Stephan looks good to me, but I think we can do better
>> for the long term approach you are discussing.
>
> What you made me think of is the following: shouldn't we relay the inline IV
> flag on to the crypto drivers?
>
> The reason is to allow a clean implementation of the enabling or disabling of
> the dependency handling in the driver. Jonathan's driver, for example, decides
> based on the pointer value of the IV buffer whether it is the same buffer and
> thus dependency handling is to be applied. This is fragile.
>
> As AF_ALG knows whether the inline IV with separate IVs per request or the
> serialization with one IV buffer for all requests is requested, it should
> relay this state on to the drivers. Thus, for example, Jonathan's driver can
> be changed to rely on this flag instead on the buffer pointer value to decide
> whether to enable its dependency handling.

Yes, that is exactly what I was trying to point out :-)

Thanks,
Gilad

-- 
Gilad Ben-Yossef
Chief Coffee Drinker

"If you take a class in large-scale robotics, can you end up in a
situation where the homework eats your dog?"
 -- Jean-Baptiste Queru



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