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SubjectRe: [PATCH v4 1/2] crypto: engine - support for parallel requests
On 3/17/2020 5:29 AM, Herbert Xu wrote:
> On Thu, Mar 12, 2020 at 12:45:54PM +0000, Iuliana Prodan wrote:
>> There are two aspects here:
>> - if all requests go through crypto-engine, and, in this case, if there
>> is no space in hw queue, do_one_req returns 0, and actually there will
>> be no case of do_one_request() < 0;
> OK, that makes sense. However, this way of signaling for more
> requests can be racy. Unless you can guarantee that the driver
> is not taking any requests from another engine queue (or any
> other source), just because it returned a positive value now does
> not mean that it would be able to take a request the next time
> you come around the loop.

This case can happen right now, also. I can't guarantee that all drivers
send all requests via crypto-engine.
This is the second aspect from my other mail. There are cases, when we
send requests (non crypto API) to hardware without passing to crypto-engine.

To solve this, I'm thinking of adding new patches that doesn't do
request dequeue from crypto-engine queue, just peek, and dequeues the
request after was successfully executed by hardware (if it has
MAY_BACKLOG flag, otherwise will dequeue it). What do you think?

Also, the above modification will imply changes in the drivers that use


>> I've tried this, but it implies modifications in all drivers. For
>> example, a driver, in case of error, it frees the resources of the
>> request. So, will need to map again a request.
> I think what we are doing here is a major overhaul to the crypto
> engine API so while it's always a good idea to minimise the impact,
> we should not let the existing drivers constrain us too much.
> Thanks,

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