Re: [PATCH 11/25] scsi: move get_scsi_ml_byte() to scsi_priv.h

[Niklas Cassel <Niklas.Cassel@wdc.com>]

On Thu, Dec 08, 2022 at 05:58:01PM -0600, Mike Christie wrote:
> On 12/8/22 4:59 AM, Niklas Cassel wrote:
> > Move get_scsi_ml_byte() to scsi_priv.h since both scsi_lib.c and
> > scsi_error.c will need to use this helper in a follow-up patch.
> > 
> > Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> > ---
> >  drivers/scsi/scsi_lib.c  | 5 -----
> >  drivers/scsi/scsi_priv.h | 5 +++++
> >  2 files changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > index 9ed1ebcb7443..d243ebc5ad54 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -579,11 +579,6 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
> >  	return false;
> >  }
> >  
> > -static inline u8 get_scsi_ml_byte(int result)
> > -{
> > -	return (result >> 8) & 0xff;
> > -}
> > -
> >  /**
> >   * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
> >   * @result:	scsi error code
> > diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
> > index 96284a0e13fe..4f97e126c6fb 100644
> > --- a/drivers/scsi/scsi_priv.h
> > +++ b/drivers/scsi/scsi_priv.h
> > @@ -29,6 +29,11 @@ enum scsi_ml_status {
> >  	SCSIML_STAT_TGT_FAILURE		= 0x04,	/* Permanent target failure */
> >  };
> >  
> > +static inline u8 get_scsi_ml_byte(int result)
> > +{
> > +	return (result >> 8) & 0xff;
> > +}
> > +
> 
> I made a mistake in the naming of this function. The get_* functions take a
> scsi_cmnd. The ones without the "get_" prefix take the scsi_cmnd->result.
> 
> Could you rename it to scsi_ml_byte() when you move it so the mistake does not
> get used in multiple places?

Hello Mike,

In scsi.h we have:
#define status_byte(result) (result & 0xff)
#define host_byte(result)   (((result) >> 16) & 0xff)

In scsi_cmnd.h we have:
static inline u8 get_status_byte(struct scsi_cmnd *cmd)
static inline u8 get_host_byte(struct scsi_cmnd *cmd)

So I see your point.


I understand that you intentionally didn't put the ML byte getter in scsi.h,
as you intentionally didn't want a LLDD to be able to get the SCSI ML byte.

However, isn't the important thing that that a LLDD can't *set* the SCSI ML
byte?
Does it really matter if a LLDD can *get* the SCSI ML byte?

If you think that it is fine that a LLD can get the SCSI ML byte,
then perhaps we should move the getter to scsi.h instead, such that
it is defined together with the other getters (which lacks a get_ prefix).


Kind regards,
Niklas