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

[yangxingui <yangxingui@xxxxxxxxxx>]

Hi Jason,

On 2024/4/18 9:46, Jason Yan wrote:
> On 2024/4/17 15:47, yangxingui wrote:
> > On 2024/4/17 9:46, Jason Yan wrote:
> > > Hi Xingui,
> > >
> > > On 2024/4/16 11:07, Xingui Yang wrote:
> > > > We found that it is judged as broadcast flutter and exits directly 
> > > > when the
> > > > exp-attached end device reconnects after the end device probe failed.
> > >
> > > Can you please describe how to reproduce this issue in detail?
> > The test steps we currently construct are to simulate link 
> > abnormalities and adjust the rate of the remote phy when running IO on 
> > all disks.
> >
> > When the sata disk is probed and the IDENTIFY command is sent to the 
> > disk, the expander return rate is abnormal, causing sata disk probe 
> > fail. But there may be many reasons for device probe failure, 
> > including expander or disk instability or link abnormalities.
> >
> > > Thanks,
> > > Jason
> > >
> > > > [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 information 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 when 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 the 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>
> > > > ---
> > > >   drivers/scsi/libsas/sas_discover.c |  2 ++
> > > >   drivers/scsi/libsas/sas_expander.c | 16 ++++++++++++++++
> > > >   drivers/scsi/libsas/sas_internal.h |  6 +++++-
> > > >   3 files changed, 23 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);
> > > >       /* 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..6ae1f4aaaf61 100644
> > > > --- a/drivers/scsi/libsas/sas_expander.c
> > > > +++ b/drivers/scsi/libsas/sas_expander.c
> > > > @@ -1856,6 +1856,22 @@ 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 expander_device *parent_ex = &parent->ex_dev;
> > > > +    int i;
> > > > +
> > > > +    for (i = 0; i < parent_ex->num_phys; i++) {
> > > > +        struct ex_phy *phy = &parent_ex->ex_phy[i];
> > > > +
> > > > +        if (sas_phy_match_dev_addr(dev, phy)) {
> > > > +            sas_unregister_devs_sas_addr(parent, i, true);
> > > > +            break;
> > > > +        }
> > > > +    }
> > >
> > > Did you mean this end device is a wide-port end device ? How could 
> > > this happen?
> >
> > No, the end device described here is a non-expander device. Such as: 
> > sata/sas disk. But these devices are exp-attached.
>
> If it is not a wide port, why do they have the same sas address here? 
> Why do you add this function to unregister these PHYs? And the last 
> parameter of sas_unregister_devs_sas_addr() means the last PHY of the 
> wide port, you just all passed true, it is irrational.
The non-expander end device does not have a wide port, such as a sata 
disk, and there is only one ex_phy corresponding to it. This function 
finds the ex_phy corresponding to the end dev through dev->sas_addr, 
then clears the ex_phy information and unregister the end device.

Thanks,
Xingui