Re: [PATCH v2 6/7] scsi: libsas: reset the phy address if discover failed

[Jason Yan]

On 2019/1/31 1:36, John Garry wrote:
> On 30/01/2019 08:24, Jason Yan wrote:
> > When we failed to discover the device, the phy address is still kept
> > in ex_phy. So when the next time we revalidate this phy the
> > address and device type is the same, it will be considered as flutter
> > and will not be discovered again. So the device will not be brought up.
> >
> > Fix this by reset the phy address to the initial value. Then
> > in the next revalidation the device will be discovered agian.
>
> Why fail to discover the device? I wonder in which scenario you have
> seen this, such that it is worth rediscovery.

The test guys have seen this for several times, especially after LLDD 
changed the logic of lldd_dev_found and may return error now.


> > Tested-by: Chen Liangfei <chenliangfei1@xxxxxxxxxx>
> > Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
> > CC: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>
> > CC: John Garry <john.garry@xxxxxxxxxx>
> > CC: Johannes Thumshirn <jthumshirn@xxxxxxx>
> > CC: Ewan Milne <emilne@xxxxxxxxxx>
> > CC: Christoph Hellwig <hch@xxxxxx>
> > CC: Tomas Henzl <thenzl@xxxxxxxxxx>
> > CC: Dan Williams <dan.j.williams@xxxxxxxxx>
> > CC: Hannes Reinecke <hare@xxxxxxxx>
> > ---
> >  drivers/scsi/libsas/sas_expander.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/scsi/libsas/sas_expander.c
> > b/drivers/scsi/libsas/sas_expander.c
> > index 6e56ebdc2148..e781941a7088 100644
> > --- a/drivers/scsi/libsas/sas_expander.c
> > +++ b/drivers/scsi/libsas/sas_expander.c
> > @@ -1100,6 +1100,13 @@ static int sas_ex_discover_dev(struct
> > domain_device *dev, int phy_id)
> >                           i, SAS_ADDR(ex->ex_phy[i].attached_sas_addr));
> >              }
> >          }
> > +    } else {
> > +        /* if we failed to discover this device, we have to
> > +         * reset the expander phy attached address so that we
> > +         * will not treat the phy as flutter in the next
> > +         * revalidation
> > +         */
> > +        memset(ex_phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
> >      }
> >
> >      return res;
>
>
>
> .