Re: [PATCH rdma v1 1/1] IB/core: Fix input len in multiple user verbs

Leon Romanovsky
2017-06-28T10:11:24Z

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On Wed, Jun 28, 2017 at 10:02:45AM +0000, Amrani, Ram wrote:
> > > Most user verbs pass user data to the kernel with the inclusion of the
> > > ib_uverbs_cmd_hdr structure. This is problematic because the vendor has
> > > no ideas if the verb was called by a legacy verb or an extended verb.
> >
> > Why vendor should know about it? It has midlayer (ib/core) between him
> > and user to handle it.
> >
>
> Knowing the inlen can be used to determine if the library is newer than
> the kernel and what features it supports or not.

It is not interesting case, because we are not breaking UAPI, only
extending. It ensures that kernel will fill as much as possible and will
always have success in it. After that it is library responsibility to
understand if everything was filled.

Thanks

>
> Ram
>
>

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