James Bottomley wrote:
On Sun, 2005-10-23 at 02:33 +0200, Stefan Richter wrote:
I just noticed that devices which require sbp2's inquiry hack are not
usable anymore. I don't know when the regression crept in since I don't
remember when I used the affected device successfully the last time. One
thing is for sure: The code change which triggered the regression took
not place in sbp2 itself.
The device in question is an older 2.5" FireWire disk, DViCO Momobay
CX-1. What happens under Linux 2.6.14-rc5 is this: Without debug logging
turned on, it seems as if the process which started the sbp2 probe
(knodemgrd or modprobe) is hanging in D state. But debug logging enabled
in sbp2 reveals that it isn't locked up but rather caught in a loop,
sending inquiry commands:
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_module_init
Oct 23 01:26:59 shuttle kernel: sbp2: $Rev: 1306 $ Ben Collins <bcollins@xxxxxxxxxx>
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_probe
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_alloc_device
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_alloc_device: allocated hostinfo
Oct 23 01:26:59 shuttle kernel: scsi0 : SCSI emulation for IEEE-1394 SBP-2 Devices
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_parse_unit_directory
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_management_agent_addr = f0010000
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_unit_characteristics = a08
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_command_set_spec_id = 609e
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_command_set = 104d8
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: sbp2_firmware_revision = 2800
Oct 23 01:26:59 shuttle kernel: ieee1394: sbp2: Node 1-01:1023: Using 36byte inquiry workaround
I don't see any looping in the traces, could you characterise what's
going on for those of us who haven't fully explored the sbp2 driver?
I cut the log. The portion
kernel: ieee1394: sbp2: sbp2scsi_queuecommand
[...]
kernel: ieee1394: sbp2: SBP2_SCSI_STATUS_CHECK_CONDITION
kernel: scsi0 : destination target 0, lun 0
kernel: command: Inquiry: 12 00 00 00 24 00
kernel: bh: Current: sense key: Unit Attention
is repeated over and over. I would have digged deeper but ran out of time.
I will look further into it during the week.
However, at a brief examination it looks like you do quite a lot of
response snooping. This always was broken for commands from userspace,
but it's completely broken now we only use scatter/gather commands from
block.
Secondly, I don't think your inquiry hack is effective any more, because
you try to alter request_bufflen, which doesn't carry the length of a
s/g command.
We have a device flag: BLIST_INQUIRY_36 which restricts the named
devices only to having 36 byte inquiries sent. Could your internal
table be migrated up to the mid-layer list to avoid the issue
altogether?
Yes, that would certainly be better.
But what about the note in scsi_devinfo.c?
* Do not add to this list, use the command line or proc interface to add
* to the scsi_dev_info_list. This table will eventually go away.
Thanks,
--
Stefan Richter
-=====-=-=-= =-=- ==---
http://arcgraph.de/sr/
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