On Thu, 30 Aug 2018 at 15:19, Stephan Mueller <smueller@xxxxxxxxxx> wrote: > > Am Donnerstag, 30. August 2018, 15:09:05 CEST schrieb Krzysztof Kozlowski: > > Hi Krzysztof, > > > Thanks Stephan for hints. Let's assume the each of init, update and > > final are atomic... but how about the relation between update and > > final? I have two concurrent users in user-space but only one HW: > > > > Process A: Process B: > > init() and set_key() > > init() and different key > > update(some_data) > > update(different_data) > > final() > > final() > > > > The final() from process A will now produce the result of hashing/CRC > > of some_data and different_data (and even maybe mixed with init() for > > different key). All because in the meantime process B added its own > > data to the HW. > > The question is where is the state of the cipher operation kept that is > produced with each of the init/update/final calls. Your answer implies that > this state is kept in hardware. Yes, that's correct. The HW once initialized to specific CRC parameters (size, polynomial, initial value), will operate on this till another init happens. > But commonly the state is kept in software. Look at ahash_request for example, > the __ctx pointer is intended to point to the memory the driver needs to store > its state. > > Pick a random driver implementation and search for ahash_request_ctx, for > example. I see now some drivers are indeed saving and restoring state. Thanks! Best regards, Krzysztof
