RE: [PATCH 0/2] mpt{2,3}sas remove disconnected phys on topology change

From: Sreekanth Reddy
Date: Tue Dec 02 2014 - 08:18:26 EST

Hi James/Chris

We are observing below issue due to this patch set code changes

Issue Description:
Drives connected Enclosure/Expander won't be visible to the OS if any
one remove and add expander cable with in DMD (Device Missing Delay) time
period (also if any power-off and power-on the Enclosure with in the DMD

Due to this code changes; driver will unregister the Enclosure port or
target PHY with SCSI transport layer, whenever driver receives "SAS
TOPOLOGY CHANGE LIST EVENT" with reason code set to "PHY link status
change" and phy link rate is Zero. Firmware usually send this type of "SAS
TOPOLOGY CHANGE LIST EVENT" event whenever drive is missing. but still
here DMD timer has not yet expired so normally driver should not
unregister the target with the SCSI transport layer instead it will move
the state of the drive to blocked state (so it won't receive any IOs from
SML for this drive).

Normally, Driver should only unregister the target with SCSI transport
layer only when driver receives "SAS TOPOLOGY CHANGE LIST EVENT" with
reason code set to "Target Remove". Firmware will send this event when the
DMD timer expires for the missing drive. If drive comes back with in the
DMD period then firmware won't send this target remove event and so driver
won't unregister the target drive with the SCSI transport layer. Driver
will just unblock the target drive to start IOs to this drive.

So, can you please revert this patch set changes back in the latest
upstream kernel and if possible on stable kernels.
I checked with the Redhat team and there are fine to revert back these
patch set changes.


>-----Original Message-----
>From: Jan Vesely [mailto:jvesely@xxxxxxxxxx]
>Sent: Thursday, August 01, 2013 3:31 PM
>To: linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>Cc: Jan Vesely; Nandigama, Nagalakshmi; Reddy, Sreekanth; Tomas Henzl
>Subject: [PATCH 0/2] mpt{2,3}sas remove disconnected phys on topology
>From: Jan Vesely <jvesely@xxxxxxxxxx>
>These two patches add phy removal on link loss. This change keeps sysfs
>up- to-date with actually connected phys. Without these patches,
>disconnected phys remain listed under their former ports.
>tested on both mpt2sas and mpt3sas hw.
>CC: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@xxxxxxx>
>CC: Sreekanth Reddy <Sreekanth.Reddy@xxxxxxx>
>CC: Tomas Henzl <thenzl@xxxxxxxxxx>
>Signed-off-by: Jan Vesely <jvesely@xxxxxxxxxx>
>Jan Vesely (2):
> mpt2sas: Remove phys on topology change.
> mpt3sas: Remove phys on topology change
> drivers/scsi/mpt2sas/mpt2sas_transport.c | 5 ++++-
> drivers/scsi/mpt3sas/mpt3sas_transport.c | 5 ++++-
> 2 files changed, 8 insertions(+), 2 deletions(-)
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