Re: [PATCH V2] scsi: libsas: Directly kick-off EH when ATA device fell off

[Jason Yan]

On 2022/12/19 17:23, John Garry wrote:
> On 16/12/2022 10:03, Xingui Yang wrote:
> > If the ATA device fell off, call sas_ata_device_link_abort() directly and
> > mark all outstanding QCs as failed and kick-off EH Immediately. This 
> > avoids
> > having to wait for block layer timeouts.
> >
> > Signed-off-by: Xingui Yang <yangxingui@xxxxxxxxxx>
> > ---
> > Changes to v1:
> > - Use dev_is_sata() to check ATA device type
> >   drivers/scsi/libsas/sas_discover.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/scsi/libsas/sas_discover.c 
> > b/drivers/scsi/libsas/sas_discover.c
> > index d5bc1314c341..a12b65eb4a2a 100644
> > --- a/drivers/scsi/libsas/sas_discover.c
> > +++ b/drivers/scsi/libsas/sas_discover.c
> > @@ -362,6 +362,9 @@ static void sas_destruct_ports(struct asd_sas_port 
> > *port)
> >   void sas_unregister_dev(struct asd_sas_port *port, struct 
> > domain_device *dev)
> >   {
> > +    if (test_bit(SAS_DEV_GONE, &dev->state) && dev_is_sata(dev))
> > +        sas_ata_device_link_abort(dev, false);
>
> Firstly, I think that there is a bug in sas_ata_device_link_abort() -> 
> ata_link_abort() code in that the host lock in not grabbed, as the 
> comment in ata_port_abort() mentions. Having said that, libsas had 
> already some dodgy host locking usage - specifically dropping the lock 
> for the queuing path (that's something else to be fixed up ... I think 

Taking big locks in queuing path is not a good idea. This will bring 
down performance.


> that is due to queue command CB calling task_done() in some cases), but 
> I still think that sas_ata_device_link_abort() should be fixed (to grab 
> the host lock).

For sas_ata_device_link_abort(), it should grab ap->lock.

Thanks,
Jason