[PATCHv3 03/11] crypto: omap-sham: implement context export/import APIs

[Tero Kristo]

On 01/09/16 09:16, Herbert Xu wrote:
> On Thu, Sep 01, 2016 at 09:12:59AM +0300, Tero Kristo wrote:
>>
>> Well, but the driver doesn't flush its buffers automatically, it
>> caches data until it has sufficient amount available. So, assuming
>> you want to do this:
>>
>> sham_init
>>   sham_update 256 bytes
>>   sham_update 256 bytes
>>   wait until two above updates are complete
>>   sham_export
>>
>> ... the execution hangs at the wait phase as the driver is still
>
> Well that's a bug in the driver.  While it's not illegal to wait
> for more data, it's usually unnecessary.  Because we instead try
> to get our users to generate as big a request as possible, e.g.,
> one packet for IPsec.
>
> If you really have to do the hold thing, then you must install a
> timer like sha1-mb does on x86 to do the flush.
>
> In any case, the completion function must not be called until
> you're actually complete.

Hmm, looking at the driver, sham_update returns 0 immediately if it just 
caches data. In a sense, the update is not completed at this point. Are 
you saying this is illegal and can't be done?

 From my understanding, valid results are expected from the driver only 
after ->final is called.

-Tero