Re: [PATCH] mpt3sas: Do scsi_remove_host() before deleting SAS PHY objects

From: Calvin Owens
Date: Mon May 16 2016 - 16:25:36 EST


On Friday 05/13 at 21:17 +0000, Elliott, Robert (Persistent Memory) wrote:
>
>
> > -----Original Message-----
> > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> > owner@xxxxxxxxxxxxxxx] On Behalf Of Calvin Owens
> > Sent: Friday, May 13, 2016 3:28 PM
> ...
> > Subject: [PATCH] mpt3sas: Do scsi_remove_host() before deleting SAS PHY
> > objects
> >
> ...
> > The issue is that enclosure_remove_device() expects to be able to re-add
> > the device that was previously enclosured: so with SES running, the order
> > we unwind things matters in a way it otherwise wouldn't.
> >
> > Since mpt3sas deletes the SAS objects before the SCSI hosts, enclosure
> > ends up trying to re-parent the SCSI device from the enclosure to the SAS
> > PHY which has already been deleted. This obviously ends in sadness.
> >
> > The fix appears to be simple: just call scsi_remove_host() before we call
> > sas_port_delete() and/or sas_remove_host().
> >
> ...
> > diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> > @@ -8149,6 +8149,8 @@ void scsih_remove(struct pci_dev *pdev)
> > _scsih_raid_device_remove(ioc, raid_device);
> > }
> >
> > + scsi_remove_host(shost);
> > +
> > /* free ports attached to the sas_host */
> > list_for_each_entry_safe(mpt3sas_port, next_port,
> > &ioc->sas_hba.sas_port_list, port_list) {
> > @@ -8172,7 +8174,6 @@ void scsih_remove(struct pci_dev *pdev)
> > }
> >
> > sas_remove_host(shost);
> > - scsi_remove_host(shost);
> > mpt3sas_base_detach(ioc);
> > spin_lock(&gioc_lock);
> > list_del(&ioc->list);
>
> That change matches the pattern of all other drivers calling
> sas_remove_host, except for one:
> drivers/message/fusion/mptsas.c
>
> That consensus means this comment in drivers/scsi/scsi_transport_sas.c
> is wrong:
>
> /**
> * sas_remove_host - tear down a Scsi_Host's SAS data structures
> * @shost: Scsi Host that is torn down
> *
> * Removes all SAS PHYs and remote PHYs for a given Scsi_Host.
> * Must be called just before scsi_remove_host for SAS HBAs.
> */

Yes, exactly: that comment appears to be backwards, and as you say most
drivers appear to do the opposite (I looked at HPSA at least, which calls
sas_port_delete() before scsi_remove_host()).

I suppose I should send a patch to fix the comment as well? It'd be nice
to get some testing to be certain I'm not breaking somebody else's setup
by fixing mine though...

Thanks,
Calvin