On Wed, Sep 16, 2015 at 11:12:41PM +0300, Alex Porosanu wrote: > caam_jr_enqueue() function returns -EBUSY once there are no > more slots available in the JR, but it doesn't actually save > the current request. This breaks the functionality of users > that expect that even if there is no more space for the request, > it is at least queued for later execution. In other words, all > crypto transformations that request backlogging > (i.e. have CRYPTO_TFM_REQ_MAY_BACKLOG set), will hang. Such an > example is dm-crypt. > The current patch solves this issue by setting a threshold after > which caam_jr_enqueue() returns -EBUSY, but since the HW job ring > isn't actually full, the job is enqueued. > Caveat: if the users of the driver don't obey the API contract which > states that once -EBUSY is received, no more requests are to be > sent, eventually the driver will reject the enqueues. This isn't what MAY_BACKLOG is supposed to do. For a given tfm at least one MAY_BACKLOG request must be accepted. So you can't just start dropping requests after your queue fills up. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
