> On 1/27/2019 10:58 AM, Nikolova, Tatyana E wrote:
> >
> >>>>> It appears the port mapping will fail, if the kernel port mapper
> >>>>> is updated with your changes but the user space port mapper isn't
> >>>>> (ABI version 3). Is there a reason why the error is silent in this case?
> >>>>>
> >>>> With testing, I see it works with kernel ABI4 and user ABI3. How do you
> >>>> see it failing exactly? Maybe I'm missing something.
> >>>>
> >>> I am referring to the following case, which anticipates mismatch
> >>> between the kernel and user space port mapper:
> >>>
> >>>> + /* If flags are required and we're not V4, then return a quite
> >>>> +error
> >> */
> >>>> + if (pm_msg->flags && iwpm_user_ulib_version ==
> >>>> IWPM_UABI_VERSION_MIN) {
> >>>> + ret = -EINVAL;
> >>>> + goto query_mapping_error_nowarn;
> >>>> + }
> >>>> + if (iwpm_user_ulib_version > IWPM_UABI_VERSION_MIN) {
> >>>> + ret = ibnl_put_attr(skb, nlh, sizeof(u32), &pm_msg->flags,
> >>>> + IWPM_NLA_QUERY_FLAGS);
> >>>> + if (ret)
> >>>> + goto query_mapping_error;
> >>>> + }
> >> Right. So if you have a V4 kernel and a V3 iwpmd, then current iwarp
> >> drivers will work fine because they aren't trying to use the new
> >> NO_PORT_MAP flag in pm_msg->flags.
> >>
> >> If, however, you have, say the soft iwarp driver running, then
> >> pm_msg->flags would be non zero. If this is the case, then the V4
> >> kernel must not send up the V4 FLAGS nlattr because the V3 iwpmd can't
> handle it.
> >> So the above code fails the map request and this results in no port
> >> mapping done for the soft iwarp driver.
> >>
> >> So we get backward compatibility with existing iwarp drivers. But
> >> new drivers that need NO_PORT_MAP will only work in the port mapping
> >> game if their local iwpmd is V4.
> >>
> > Hi Steve,
> >
> > Thank you for the explanation.
> >
> > I think that you don't need to make the error silent in this case. You could go
> through the standard error path, where the error is logged and people are
> going to know about it. This is going to prompt them to update to a more
> current rdma-core which has your changes.
> >
> > I understand that the error doesn't matter in the case of soft iwarp devices
> talking to each other, since they don't need a port mapper. However, in the
> case of a soft iwarp device talking to an iwarp peer which uses the port
> mapper, the error reporting is going to be useful, since the connection
> establishment won't succeed.
> >
> > Regards,
> > Tatyana
>
> That makes sense. But I only want a warn_once() type of warning. Thanks for
> reviewing this. I'll respin it soon.
>
> May I add your reviewed-by tag?
Sure. Thanks!
>
> Steve.
