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Kenneth D. Merry 28ef82eb7b Change the isp(4) driver to not adjust the tag type for REQUEST SENSE.
The isp(4) driver was changing the tag type for REQUEST SENSE
commands to Head of Queue, when the CAM CCB flag
CAM_TAG_ACTION_VALID was NOT set.  CAM_TAG_ACTION_VALID is set
when the tag action in the XPT_SCSI_IO is not CAM_TAG_ACTION_NONE
and when the target has tagged queueing turned on.

In most cases when CAM_TAG_ACTION_VALID is not set, it is because
the target is not doing tagged queueing.  In those cases, trying to
send a Head of Queue tag may cause problems.  Instead, default to
sending a simple tag.

IBM tape drives claim to support tagged queueing in their standard
Inquiry data, but have the DQue bit set in the control mode page
(mode page 10).  CAM correctly detects that these drives do not
support tagged queueing, and clears the CAM_TAG_ACTION_VALID flag
on CCBs sent down to the drives.

This caused the isp(4) driver to go down the path of setting the
tag action to a default value, and for Request Sense commands only,
set the tag action to Head of Queue.

If an IBM tape drive does get a Head of Queue tag, it rejects it with
Invalid Message Error (0x49,0x00).  (The Qlogic firmware translates that
to a Transport Error, which the driver translates to an Unrecoverable
HBA Error, or CAM_UNREC_HBA_ERROR.) So, by default, it wasn't possible
to get a good response from a REQUEST SENSE to an FC-attached IBM
tape drive with the isp(4) driver.

IBM tape drives (tested on an LTO-5 with G9N1 firmware and a TS1150
with 4470 firmware) also have a bug in that sending a command with a
non-simple tag attribute breaks the tape drive's Command Reference
Number (CRN) accounting and causes it to ignore all subsequent
commands because it and the initiator disagree about the next
expected CRN.  The drives do reject the initial command with a head
of queue tag with an Invalid Message Error (0x49,0x00), but after that
they ignore any subsequent commands.  IBM confirmed that it is a bug,
and sent me test firmware that fixes the bug.  However tape drives in
the field will still exhibit the bug until they are upgraded.

Request Sense is not often sent to targets because most errors are
reported automatically through autosense in Fibre Channel and other
modern transports.  ("Modern" meaning post SCSI-2.)  So this is not
an error that would crop up frequently.  But Request Sense is useful on
tape devices to report status information, aside from error reporting.

This problem is less serious without FC-Tape features turned on,
specifically precise delivery of commands (which enables Command
Reference Numbers), enabled on the target and initiator.  Without
FC-Tape features turned on, the target would return an error and
things would continue on.

And it also does not cause problems for targets that do tagged
queueing, because in those cases the isp(4) driver just uses the
tag type that is specified in the CCB, assuming the
CAM_TAG_ACTION_VALID flag is set, and defaults to sending a Simple
tag action if it isn't an ordered or head of queue tag.

sys/dev/isp/isp.c:
	In isp_start(), don't try to send Request Sense commands
	with the Head of Queue tag attribute if the CCB doesn't
	have a valid tag action.  The tag action likely isn't valid
	because the target doesn't support tagged queueing.

Sponsored by:	Spectra Logic
MFC after:	3 days
2017-02-10 22:02:45 +00:00
bin Remove bdes(1) 2017-02-06 08:27:19 +00:00
cddl When patching USDT probes, use non-unique names for aliases of weak symbols. 2017-02-10 02:01:32 +00:00
contrib Don't check struct rtentry on FreeBSD, it is an internal kernel structure. 2017-02-10 17:34:48 +00:00
crypto Merge OpenSSL 1.0.2k. 2017-01-26 19:10:29 +00:00
etc MFhead@r313360 2017-02-07 01:33:39 +00:00
gnu Bump GCC FBSD_CC_VER for r312899 (-march=octeon+ support) 2017-02-01 05:24:17 +00:00
include Make use of clang nullability attributes. 2017-01-28 20:54:43 +00:00
kerberos5 Conditionalize adding ${KRB5DIR}/lib/gssapi/krb5/gkrb5_err.et to ETSRCS 2017-01-02 19:03:01 +00:00
lib ufs: Use UFS_MAXNAMLEN constant 2017-02-09 17:47:01 +00:00
libexec Handle protected symbols in rtld. 2017-02-09 23:33:06 +00:00
release Add some comments with examples on how to build Vagrant images. 2017-02-01 16:15:23 +00:00
rescue Remove pc98 support completely. 2017-01-28 02:22:15 +00:00
sbin ufs: Use UFS_MAXNAMLEN constant 2017-02-09 17:47:01 +00:00
secure Remove bdes(1) 2017-02-06 08:27:19 +00:00
share Merge projects/ipsec into head/. 2017-02-06 08:49:57 +00:00
sys Change the isp(4) driver to not adjust the tag type for REQUEST SENSE. 2017-02-10 22:02:45 +00:00
targets Remove pc98 support completely. 2017-01-28 02:22:15 +00:00
tests Expect :mmap__bad_arguments to fail 2017-02-10 19:31:09 +00:00
tools o Add mkimg to the cross tools, and use the TMPPATH as PATH to pick up 2017-02-06 06:15:38 +00:00
usr.bin indent(1): add regression test cases 2017-02-10 09:31:39 +00:00
usr.sbin kldxref: bump MAXSEGS to 3 2017-02-10 19:17:10 +00:00
.arcconfig callsign isn't required anymore 2016-09-29 06:19:45 +00:00
.arclint phabricator related changes: 2015-04-20 20:33:22 +00:00
COPYRIGHT Bump copyright year. 2016-12-31 12:41:42 +00:00
LOCKS
MAINTAINERS Remove myself from kern_timeout.c yeah! 2016-07-27 20:37:32 +00:00
Makefile Remove pc98 support completely. 2017-01-28 02:22:15 +00:00
Makefile.inc1 Remove LOCAL_LIB_DIRS warning added in r275839. 2017-02-04 02:15:49 +00:00
Makefile.libcompat Use cross-NM (XNM) in compat32 build 2017-01-27 03:43:18 +00:00
ObsoleteFiles.inc Add ObsoleteFiles entries for bdes(1) missed in r313329 2017-02-06 10:51:53 +00:00
README README: remove nonexistent 'games' directory. 2016-05-18 10:43:13 +00:00
UPDATING Rename LLD_AS_LD to LLD_IS_LD, for consistency with CLANG_IS_CC 2017-01-27 01:59:12 +00:00

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