Re: [dpdk-dev] [EXT] Re: [PATCH v2 1/3] cryptodev: remove LIST_END enumerators

[Thomas Monjalon <thomas@monjalon.net>]

12/10/2021 15:38, Anoob Joseph:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 12/10/2021 13:34, Anoob Joseph:
> > > From: Kinsella, Ray <mdr@ashroe.eu>
> > > > On 12/10/2021 11:50, Anoob Joseph wrote:
> > > > > From: Akhil Goyal <gakhil@marvell.com>
> > > > >>> On 08/10/2021 21:45, Akhil Goyal wrote:
> > > > >>>> Remove *_LIST_END enumerators from asymmetric crypto lib to
> > > > >>>> avoid ABI breakage for every new addition in enums.
> > > > >>>>
> > > > >>>> Signed-off-by: Akhil Goyal <gakhil@marvell.com>
> > > > >>>> ---
> > > > >>>> -	} else if (xform->xform_type >=
> > > > >>> RTE_CRYPTO_ASYM_XFORM_TYPE_LIST_END
> > > > >>>> +	} else if (xform->xform_type >
> > RTE_CRYPTO_ASYM_XFORM_ECPM
> > [...]
> > > > >>>
> > > > >>> So I am not sure that this is an improvement.
> > 
> > Indeed, it is not an improvement.
> > 
> > > > >>> The cryptodev issue we had, was that _LIST_END was being used to
> > > > >>> size arrays.
> > > > >>> And that broke when new algorithms got added. Is that an issue,
> > > > >>> in this
> > > > case?
> > > > >>
> > > > >> Yes we did this same exercise for symmetric crypto enums earlier.
> > > > >> Asym enums were left as it was experimental at that point.
> > > > >> They are still experimental, but thought of making this uniform
> > > > >> throughout DPDK enums.
> > > > >>
> > > > >>>
> > > > >>> I am not sure that swapping out _LIST_END, and then littering
> > > > >>> the code with RTE_CRYPTO_ASYM_XFORM_ECPM and
> > > > >>> RTE_CRYPTO_ASYM_OP_SHARED_SECRET_COMPUTE, is an
> > improvement
> > > > >> here.
> > > > >>>
> > > > >>> My 2c is that from an ABI PoV RTE_CRYPTO_ASYM_OP_LIST_END is not
> > > > >>> better or worse, than
> > > > RTE_CRYPTO_ASYM_OP_SHARED_SECRET_COMPUTE?
> > > > >>>
> > > > >>> Interested to hear other thoughts.
> > > > >>
> > > > >> I don’t have any better solution for avoiding ABI issues for now.
> > > > >> The change is for avoiding ABI breakage. But we can drop this
> > > > >> patch For now as asym is still experimental.
> > > > >
> > > > > [Anoob] Having LIST_END would preclude new additions to asymmetric
> > algos?
> > > > If yes, then I would suggest we address it now.
> > > >
> > > > Not at all - but it can be problematic, if two versions of DPDK
> > > > disagree with the value of LIST_END.
> > > >
> > > > > Looking at the "problematic changes", we only have 2-3 application
> > > > > & PMD changes. For unit test application, we could may be do
> > > > > something like,
> > > >
> > > > The essental functionality not that different, I am just not sure
> > > > that the verbosity below is helping.
> > > > What you are really trying to guard against is people using LIST_END
> > > > to size arrays.
> > >
> > > [Anoob] Our problem is application using LIST_END (which comes from library)
> > to determine the number of iterations for the loop. My suggestion is to modify
> > the UT such that, we could use RTE_DIM(types) (which comes from application)
> > to determine iterations of loop. This would solve the problem, right?
> > 
> > The problem is not the application.
> > Are you asking the app to define DPDK types?
> 
> [Anoob] I didn't understand how you concluded that.

Because you define a specific array in the test app.

> The app is supposed to test "n" asymmetric features supported by DPDK. Currently, it does that by looping from 0 to LIST_END which happens to give you the first n features. Now, if we add any new asymmetric feature, LIST_END value would change. Isn't that the very reason why we removed LIST_END from symmetric library and applications?

Yes

> Now coming to what I proposed, the app is supposed to test "n" asymmetric features. LIST_END helps in doing the loops. If we remove LIST_END, then application will not be in a position to do a loop. My suggestion is, we list the types that are supposed to be tested by the app, and let that array be used as feature list.
> 
> PS: Just to reiterate, my proposal is just a local array which would hold DPDK defined RTE enum values for the features that would be tested by this app/function.

I am more concerned by the general case than the test app.
I think a function returning a number is more app-friendly.

> > > > > +               enum rte_crypto_asym_op_type types[] = { 
> 
> > 
> > The problem is in DPDK API. We must not suggest a size for enums.
> 
> [Anoob] So agreed that LIST_END should be removed?

Yes

> > If we really need a size, then it must be explicit and updated in the lib binary
> > (through a function) when the size increases.
> 
> [Anoob] Precisely my thoughts. The loop with LIST_END done in application is not correct. 
> > 
> > 
> > 
> > > > > -               for (i = 0; i < RTE_CRYPTO_ASYM_OP_LIST_END; i++) {
> > > > > +               enum rte_crypto_asym_op_type types[] = {
> > > > > +                               RTE_CRYPTO_ASYM_OP_ENCRYPT,
> > > > > +                               RTE_CRYPTO_ASYM_OP_DECRYPT,
> > > > > +                               RTE_CRYPTO_ASYM_OP_SIGN,
> > > > > +                               RTE_CRYPTO_ASYM_OP_VERIFY,
> > > > > +                               RTE_CRYPTO_ASYM_OP_PRIVATE_KEY_GENERATE,
> > > > > +                               RTE_CRYPTO_ASYM_OP_PUBLIC_KEY_GENERATE,
> > > > > +                               RTE_CRYPTO_ASYM_OP_SHARED_SECRET_COMPUTE,
> > > > > +               };
> > > > > +               for (i = 0; i <= RTE_DIM(types); i++) {
> > > > >                         if (tc.modex.xform_type ==
> > RTE_CRYPTO_ASYM_XFORM_RSA) {
> > > > > -                               if (tc.rsa_data.op_type_flags & (1 << i)) {
> > > > > +                               if (tc.rsa_data.op_type_flags & (1
> > > > > + <<
> > > > > + types[i])) {
> > > > >                                         if (tc.rsa_data.key_exp) {
> > > > >                                                 status = test_cryptodev_asym_op(
> > > > >                                                         &testsuite_params, &tc,
> > > > > -                                                       test_msg, sessionless, i,
> > > > > +                                                       test_msg,
> > > > > + sessionless, types[i],
> > > > >                                                         RTE_RSA_KEY_TYPE_EXP);
> > > > >                                         }
> > > > >                                         if (status)
> > > > >                                                 break;
> > > > > -                                       if (tc.rsa_data.key_qt && (i ==
> > > > > +                                       if (tc.rsa_data.key_qt &&
> > > > > + (types[i] ==
> > > > >                                                         RTE_CRYPTO_ASYM_OP_DECRYPT ||
> > > > > -                                                       i == RTE_CRYPTO_ASYM_OP_SIGN)) {
> > > > > +                                                       types[i]
> > > > > + ==
> > > > > + RTE_CRYPTO_ASYM_OP_SIGN)) {
> > > > >                                                 status = test_cryptodev_asym_op(
> > > > >                                                         &testsuite_params,
> > > > > -                                                       &tc, test_msg, sessionless, i,
> > > > > +                                                       &tc,
> > > > > + test_msg, sessionless, types[i],
> > > > >                                                         RTE_RSA_KET_TYPE_QT);
> > > > >                                         }
> > > > >                                         if (status)
> > > > >
> > > > > This way, application would only use the ones which it is designed
> > > > > to work
> > > > with. For QAT driver changes, we could have an overload if condition
> > > > (if alg == x
> > > > || alg = y || ...) to get the same effect.