Re: [PATCH] ata: libata-eh: Clarify ata_eh_qc_retry() behavior at call site

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

On Mon, May 22, 2023 at 09:48:24AM +0900, Damien Le Moal wrote:
> On 5/19/23 19:40, Niklas Cassel wrote:
> > From: Niklas Cassel <niklas.cassel@wdc.com>
> > 
> > While the function documentation for ata_eh_qc_retry() is clear,
> > from simply reading the single function that calls ata_eh_qc_retry(),
> > it is not clear that ata_eh_qc_retry() might not retry the command.
> > 
> > Add a comment in the single function that calls ata_eh_qc_retry() to
> > clarify the behavior.
> 
> Looks good. But may be resend this rebased on top of Hannes v2 of the error
> handler cleanup once he sends it ?

Still no v2 from Hannes yet, and considering that Hannes' series does not
touch this function (ata_eh_finish()) at all, perhaps this can be queued?


Kind regards,
Niklas

> 
> > 
> > Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> > ---
> >  drivers/ata/libata-eh.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> > index a6c901811802..170326dc1073 100644
> > --- a/drivers/ata/libata-eh.c
> > +++ b/drivers/ata/libata-eh.c
> > @@ -3814,6 +3814,12 @@ void ata_eh_finish(struct ata_port *ap)
> >  			 * considering both err_mask and tf.
> >  			 */
> >  			if (qc->flags & ATA_QCFLAG_RETRY)
> > +				/*
> > +				 * Since qc->err_mask is set, ata_eh_qc_retry()
> > +				 * will not increment scmd->allowed, so upper
> > +				 * layer will only retry the command if it has
> > +				 * not already been retried too many times.
> > +				 */
> >  				ata_eh_qc_retry(qc);
> >  			else
> >  				ata_eh_qc_complete(qc);
> > @@ -3823,6 +3829,12 @@ void ata_eh_finish(struct ata_port *ap)
> >  			} else {
> >  				/* feed zero TF to sense generation */
> >  				memset(&qc->result_tf, 0, sizeof(qc->result_tf));
> > +				/*
> > +				 * Since qc->err_mask is not set,
> > +				 * ata_eh_qc_retry() will increment
> > +				 * scmd->allowed, so upper layer is guaranteed
> > +				 * to retry the command.
> > +				 */
> >  				ata_eh_qc_retry(qc);
> >  			}
> >  		}
> 
> -- 
> Damien Le Moal
> Western Digital Research
>