Re: [PATCH] scsi: libsas: Fix disk not being scanned in after being removed

[yangxingui]

Hi, John

On 2024/2/22 20:41, John Garry wrote:
> On 21/02/2024 07:31, Xingui Yang wrote:
> > As of commit d8649fc1c5e4 ("scsi: libsas: Do discovery on empty PHY to
> > update PHY info"), do discovery will send a new SMP_DISCOVER and update
> > phy->phy_change_count. We found that if the disk is reconnected and phy
> > change_count changes at this time, the disk scanning process will not be
> > triggered.
> >
> > So update the PHY info with the last query results.
> >
> > Fixes: d8649fc1c5e4 ("scsi: libsas: Do discovery on empty PHY to 
> > update PHY info")
> > Signed-off-by: Xingui Yang <yangxingui@xxxxxxxxxx>
> > ---
> >   drivers/scsi/libsas/sas_expander.c | 9 ++++-----
> >   1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/scsi/libsas/sas_expander.c 
> > b/drivers/scsi/libsas/sas_expander.c
> > index a2204674b680..9563f5589948 100644
> > --- a/drivers/scsi/libsas/sas_expander.c
> > +++ b/drivers/scsi/libsas/sas_expander.c
> > @@ -1681,6 +1681,10 @@ int sas_get_phy_attached_dev(struct 
> > domain_device *dev, int phy_id,
> >           if (*type == 0)
> >               memset(sas_addr, 0, SAS_ADDR_SIZE);
> >       }
> > +
> > +    if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM))
> > +        sas_set_ex_phy(dev, phy_id, disc_resp);
> > +
> >       kfree(disc_resp);
> >       return res;
> >   }
> > @@ -1972,11 +1976,6 @@ static int sas_rediscover_dev(struct 
> > domain_device *dev, int phy_id,
> >       if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM)) {
> >           phy->phy_state = PHY_EMPTY;
> >           sas_unregister_devs_sas_addr(dev, phy_id, last);
> > -        /*
> > -         * Even though the PHY is empty, for convenience we discover
> > -         * the PHY to update the PHY info, like negotiated linkrate.
> > -         */
> > -        sas_ex_phy_discover(dev, phy_id);
>
> It would be nice to be able to call sas_set_ex_phy() here (instead of 
> sas_get_phy_attached_dev()), but I assume that you can't do that as the 
> disc_resp memory is not available.
>
> If we were to manually set the PHY info here instead, how would that look?
Yes, I think it is indeed better to use sas_set_ex_phy, as you said, 
disc_resp memory is not available. Maybe we can use sas_get_phy_discover 
instead of sas_get_phy_attached_dev so we can use disc_resp?
as follow:
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -1940,6 +1940,7 @@ static int sas_rediscover_dev(struct domain_device 
*dev, int phy_id,
        struct expander_device *ex = &dev->ex_dev;
        struct ex_phy *phy = &ex->ex_phy[phy_id];
        enum sas_device_type type = SAS_PHY_UNUSED;
+       struct smp_disc_resp *disc_resp;
        u8 sas_addr[SAS_ADDR_SIZE];
        char msg[80] = "";
        int res;
@@ -1951,33 +1952,41 @@ static int sas_rediscover_dev(struct 
domain_device *dev, int phy_id,
                 SAS_ADDR(dev->sas_addr), phy_id, msg);

        memset(sas_addr, 0, SAS_ADDR_SIZE);
-       res = sas_get_phy_attached_dev(dev, phy_id, sas_addr, &type);
+       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE);
+       if (!disc_resp)
+               return -ENOMEM;
+       res = sas_get_phy_discover(dev, phy_id, disc_resp);
..
-               /*
-                * Even though the PHY is empty, for convenience we discover
-                * the PHY to update the PHY info, like negotiated linkrate.
-                */
-               sas_ex_phy_discover(dev, phy_id);
-               return res;
+		if (res == 0)
+               	sas_set_ex_phy(dev, phy_id, disc_resp);
+               goto out;

..

+out:
+	kfree(disc_resp);
+	return res;

Thanks.
Xingui