Re: [PATCH V2 resend] libata:fix kernel panic when hotplug

[dingxiang]

Hi,All
> Hello,
>
> On Mon, Jun 20, 2016 at 06:46:55PM -0700, Dan Williams wrote:
> > On Mon, Jun 20, 2016 at 6:22 PM, Martin K. Petersen
> > <martin.petersen@xxxxxxxxxx> wrote:
> > > > > > > > "Tejun" == Tejun Heo <tj@xxxxxxxxxx> writes:
> > > > > In fact,we don't need libata to deal with hotplug in sas environment.
> > > > > So we can't run ata hotplug task when ata port is sas host.
> > > Tejun> Martin, can you please confirm whether the above is true.  If so,
> > > Tejun> I'll route the patch through libata w/ stable cc'd.
> > >
> > > Not exactly a libsas expert. James? Dan?
> > While it is true that libsas itself handles adding / removing devices
> > we have historically avoided this conflict because
> > ATA_PFLAG_SCSI_HOTPLUG is never set for libsas ata_ports.  So the bug
> > / behavior change is that  ATA_PFLAG_SCSI_HOTPLUG gets set in the
> > first place.  Ignoring it is a band-aid / not the real fix afaics.
> I see.  I'll hold off for now then.  Ding Xiang, can you find out
> where that flag is getting set?
>
> Thanks!
There are two places will set flag ATA_PFLAG_SCSI_HOTPLUG in libata-eh.c.
I think both places should  be protected. Here is the suggestion.
Thanks~

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 61dc7a9..2bee041 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1385,7 +1385,8 @@ void ata_eh_detach_dev(struct ata_device *dev)

        if (ata_scsi_offline_dev(dev)) {
                dev->flags |= ATA_DFLAG_DETACHED;
-               ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
+               if (!(ap->pflags & ATA_FLAG_SAS_HOST))
+                       ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
        }

        /* clear per-dev EH info */
@@ -3299,7 +3300,8 @@ static int ata_eh_revalidate_and_attach(struct 
ata_link *link,
                }

                spin_lock_irqsave(ap->lock, flags);
-               ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
+               if (!(ap->pflags & ATA_FLAG_SAS_HOST))
+                       ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
                spin_unlock_irqrestore(ap->lock, flags);

                /* new device discovered, configure xfermode */