Re: [PATCH 1/2] include: uapi: scsi: Change utp_upiu_query struct

[Bart Van Assche <bvanassche@xxxxxxx>]

On 3/1/23 01:46, Arthur Simchaev wrote:
> > > > >    struct utp_upiu_query {
> > > > >      __u8 opcode;
> > > > >      __u8 idn;
> > > > >      __u8 index;
> > > > >      __u8 selector;
> > > > > -   __be16 reserved_osf;
> > > > > -   __be16 length;
> > > > > -   __be32 value;
> > > > > -   __be32 reserved[2];
> > > > > +   __u8 osf3;
> > > > > +   __u8 osf4;
> > > > > +   __be16 osf5;
> > > > > +   __be32 osf6;
> > > > > +   __be32 osf7;
> > > > >    };
> > > > All changes in UAPI headers must be backwards compatible. The above
> > doesn't look like a backwards compatible change to me.
> > > This API was originally invented to support ufs-bsg.
> > > AFAIK, ufs-utils is the only app that makes use of this API,
> > > and it doesn't dig into struct utp_upiu_query inner fields.
> >
> > That does not match what I see. I see that code in ufs-utils accesses
> > the 'length' and 'value' members of the above data structure.
> >
> > Please follow the rules for UAPI header files.
> >
> > Thanks,
> >
> > Bart.
>
> You are right , my fault.
> Anyway, It just return reserved field to the struct.
> Also I can update the tool accordingly. Instead length and value fields,
> using osf5 and osf6.
> In this case we will keep it backward compatible.
> Is it OK?

Hi Arthur,

I doubt that renaming structure members is acceptable for UAPI headers. 
How about introducing a second struct next to the utp_upiu_query struct?

Thanks,

Bart.