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

[John Garry]

On 31/01/2019 02:13, Jason Yan wrote:
> 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

/s/phy/PHY/

> > > 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.

We're finding that a specific SATA disk stays in STP pending for some 
time and we fail the init in lldd dev found, like you say.

However, I think that we should ensure that this passes, as with your 
change I find we get some looping of dev found and lost until it finally 
recovers.

Regardless, I think that your change on its own is ok, so:
Reviewed-by: John Garry <john.garry@xxxxxxxxxx>


> > > 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;
> >
> >
> >
> > .
>
>
> .