Re: [PATCH v2] scsi: libsas: Fix exp-attached end device cannot be scanned in again after probe failed

[yangxingui <yangxingui@xxxxxxxxxx>]

Hi John,

Thank you for your reply

On 2024/5/24 16:36, John Garry wrote:
> On 24/04/2024 09:08, Xingui Yang wrote:
> > We found that it is judged as broadcast flutter when the exp-attached end
> > device reconnects after probe failed, as follows:
> >
> > [78779.654026] sas: broadcast received: 0
> > [78779.654037] sas: REVALIDATING DOMAIN on port 0, pid:10
> > [78779.654680] sas: ex 500e004aaaaaaa1f phy05 change count has changed
> > [78779.662977] sas: ex 500e004aaaaaaa1f phy05 originated 
> > BROADCAST(CHANGE)
> > [78779.662986] sas: ex 500e004aaaaaaa1f phy05 new device attached
> > [78779.663079] sas: ex 500e004aaaaaaa1f phy05:U:8 attached: 
> > 500e004aaaaaaa05 (stp)
> > [78779.693542] hisi_sas_v3_hw 0000:b4:02.0: dev[16:5] found
> > [78779.701155] sas: done REVALIDATING DOMAIN on port 0, pid:10, res 0x0
> > [78779.707864] sas: Enter sas_scsi_recover_host busy: 0 failed: 0
> > ...
> > [78835.161307] sas: --- Exit sas_scsi_recover_host: busy: 0 failed: 0 
> > tries: 1
> > [78835.171344] sas: sas_probe_sata: for exp-attached device 
> > 500e004aaaaaaa05 returned -19
> > [78835.180879] hisi_sas_v3_hw 0000:b4:02.0: dev[16:5] is gone
> > [78835.187487] sas: broadcast received: 0
> > [78835.187504] sas: REVALIDATING DOMAIN on port 0, pid:10
> > [78835.188263] sas: ex 500e004aaaaaaa1f phy05 change count has changed
> > [78835.195870] sas: ex 500e004aaaaaaa1f phy05 originated 
> > BROADCAST(CHANGE)
> > [78835.195875] sas: ex 500e004aaaaaaa1f rediscovering phy05
> > [78835.196022] sas: ex 500e004aaaaaaa1f phy05:U:A attached: 
> > 500e004aaaaaaa05 (stp)
> > [78835.196026] sas: ex 500e004aaaaaaa1f phy05 broadcast flutter
> > [78835.197615] sas: done REVALIDATING DOMAIN on port 0, pid:10, res 0x0
> >
> > The cause of the problem is that the related ex_phy's 
> > attached_sas_addr was
> > not cleared after the end device probe failed. In order to solve the 
> > above
> > problem, a function sas_ex_unregister_end_dev() is defined to clear the
> > ex_phy information and unregister the end device after the 
> > exp-attached end
> > device probe failed.
> >
> > As the sata device is an asynchronous probe, the sata device may probe
> > failed after done REVALIDATING DOMAIN. Then after its port is added to 
> > the
> > sas_port_del_list, the port will not be deleted until the end of the next
> > REVALIDATING DOMAIN and sas_destruct_ports() is called. A warning about
> > creating a duplicate port will occur in the new REVALIDATING DOMAIN when
> > the end device reconnects. Therefore, the previous destroy_list and
> > sas_port_del_list should be handled before REVALIDATING DOMAIN.
> >
> > Signed-off-by: Xingui Yang <yangxingui@xxxxxxxxxx>
> > ---
> > Changes since v1:
> > - Simplify the process of getting ex_phy id based on Jason's suggestion.
> > - Update commit information.
> > ---
> >   drivers/scsi/libsas/sas_discover.c | 2 ++
> >   drivers/scsi/libsas/sas_expander.c | 8 ++++++++
> >   drivers/scsi/libsas/sas_internal.h | 6 +++++-
> >   3 files changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/libsas/sas_discover.c 
> > b/drivers/scsi/libsas/sas_discover.c
> > index 8fb7c41c0962..aae90153f4c6 100644
> > --- a/drivers/scsi/libsas/sas_discover.c
> > +++ b/drivers/scsi/libsas/sas_discover.c
> > @@ -517,6 +517,8 @@ static void sas_revalidate_domain(struct 
> > work_struct *work)
> >       struct sas_ha_struct *ha = port->ha;
> >       struct domain_device *ddev = port->port_dev;
> > +    sas_destruct_devices(port);
> > +    sas_destruct_ports(port);
>
> We still have both these same calls at the @out label - is that as desired?
Yes, I think so
> Why do these new additions not cover the same job which those calls to 
> the same functions @out covers?
For asynchronous probes like sata, the failure occurs after @out. After 
adding the device to port_delete_list, the port is not deleted 
immediately. This may cause the device to fail to create a new port 
because the previous port has not been deleted when the device attached 
again. as follow:

1. REVALIDATING DOMAIN
2. new device attached
3. ata_sas_async_probe
4. done REVALIDATING DOMAIN
5. @out, handle parent->port->sas_port_del_list
6. sata probe failed
7. add phy->port->list to parent->port->sas_port_del_list // port won't 
delete now

8、REVALIDATING DOMAIN
9、new device attached
10、new port create failed, as port already exits.

> >       /* prevent revalidation from finding sata links in recovery */
> >       mutex_lock(&ha->disco_mutex);
> >       if (test_bit(SAS_HA_ATA_EH_ACTIVE, &ha->state)) {
> > diff --git a/drivers/scsi/libsas/sas_expander.c 
> > b/drivers/scsi/libsas/sas_expander.c
> > index f6e6db8b8aba..45793c10009b 100644
> > --- a/drivers/scsi/libsas/sas_expander.c
> > +++ b/drivers/scsi/libsas/sas_expander.c
> > @@ -1856,6 +1856,14 @@ static void sas_unregister_devs_sas_addr(struct 
> > domain_device *parent,
> >       }
> >   }
> > +void sas_ex_unregister_end_dev(struct domain_device *dev)
> > +{
> > +    struct domain_device *parent = dev->parent;
> > +    struct sas_phy *phy = dev->phy;
> > +
> > +    sas_unregister_devs_sas_addr(parent, phy->number, true);
> > +}
> > +
> >   static int sas_discover_bfs_by_root_level(struct domain_device *root,
> >                         const int level)
> >   {
> > diff --git a/drivers/scsi/libsas/sas_internal.h 
> > b/drivers/scsi/libsas/sas_internal.h
> > index 3804aef165ad..434f928c2ed8 100644
> > --- a/drivers/scsi/libsas/sas_internal.h
> > +++ b/drivers/scsi/libsas/sas_internal.h
> > @@ -50,6 +50,7 @@ void sas_discover_event(struct asd_sas_port *port, 
> > enum discover_event ev);
> >   void sas_init_dev(struct domain_device *dev);
> >   void sas_unregister_dev(struct asd_sas_port *port, struct 
> > domain_device *dev);
> > +void sas_ex_unregister_end_dev(struct domain_device *dev);
> >   void sas_scsi_recover_host(struct Scsi_Host *shost);
> > @@ -145,7 +146,10 @@ static inline void sas_fail_probe(struct 
> > domain_device *dev, const char *func, i
> >           func, dev->parent ? "exp-attached" :
> >           "direct-attached",
> >           SAS_ADDR(dev->sas_addr), err);
> > -    sas_unregister_dev(dev->port, dev);
> > +    if (dev->parent && !dev_is_expander(dev->dev_type))
>
> This check looks odd.
>
> So we're checking if we have a parent device and we are not an expander, 
> right?
Yes.
> > +        sas_ex_unregister_end_dev(dev);
> > +    else
> > +        sas_unregister_dev(dev->port, dev);
> >   }
> >   static inline void sas_fill_in_rphy(struct domain_device *dev,
>
> .

Thanks,
Xingui