linux-toradex.git/drivers/scsi/scsi_error.c, branch v3.4.40

SCSI: Fix 'Device not ready' issue on mpt2sas

2012-09-14T17:00:32+00:00

commit 14216561e164671ce147458653b1fea06a4ada1e upstream.

This is a particularly nasty SCSI ATA Translation Layer (SATL) problem.

SAT-2 says (section 8.12.2)

        if the device is in the stopped state as the result of
        processing a START STOP UNIT command (see 9.11), then the SATL
        shall terminate the TEST UNIT READY command with CHECK CONDITION
        status with the sense key set to NOT READY and the additional
        sense code of LOGICAL UNIT NOT READY, INITIALIZING COMMAND
        REQUIRED;

mpt2sas internal SATL seems to implement this.  The result is very confusing
standby behaviour (using hdparm -y).  If you suspend a drive and then send
another command, usually it wakes up.  However, if the next command is a TEST
UNIT READY, the SATL sees that the drive is suspended and proceeds to follow
the SATL rules for this, returning NOT READY to all subsequent commands.  This
means that the ordering of TEST UNIT READY is crucial: if you send TUR and
then a command, you get a NOT READY to both back.  If you send a command and
then a TUR, you get GOOD status because the preceeding command woke the drive.

This bit us badly because

commit 85ef06d1d252f6a2e73b678591ab71caad4667bb
Author: Tejun Heo 
Date:   Fri Jul 1 16:17:47 2011 +0200

    block: flush MEDIA_CHANGE from drivers on close(2)

Changed our ordering on TEST UNIT READY commands meaning that SATA drives
connected to an mpt2sas now suspend and refuse to wake (because the mpt2sas
SATL sees the suspend *before* the drives get awoken by the next ATA command)
resulting in lots of failed commands.

The standard is completely nuts forcing this inconsistent behaviour, but we
have to work around it.

The fix for this is twofold:

   1. Set the allow_restart flag so we wake the drive when we see it has been
      suspended

   2. Return all TEST UNIT READY status directly to the mid layer without any
      further error handling which prevents us causing error handling which
      may offline the device just because of a media check TUR.

Reported-by: Matthias Prager 
Signed-off-by: James Bottomley 
Signed-off-by: Greg Kroah-Hartman

SCSI: fix eh wakeup (scsi_schedule_eh vs scsi_restart_operations)

2012-08-09T15:31:27+00:00

commit 57fc2e335fd3c2f898ee73570dc81426c28dc7b4 upstream.

Rapid ata hotplug on a libsas controller results in cases where libsas
is waiting indefinitely on eh to perform an ata probe.

A race exists between scsi_schedule_eh() and scsi_restart_operations()
in the case when scsi_restart_operations() issues i/o to other devices
in the sas domain.  When this happens the host state transitions from
SHOST_RECOVERY (set by scsi_schedule_eh) back to SHOST_RUNNING and
->host_busy is non-zero so we put the eh thread to sleep even though
->host_eh_scheduled is active.

Before putting the error handler to sleep we need to check if the
host_state needs to return to SHOST_RECOVERY for another trip through
eh.  Since i/o that is released by scsi_restart_operations has been
blocked for at least one eh cycle, this implementation allows those
i/o's to run before another eh cycle starts to discourage hung task
timeouts.

Reported-by: Tom Jackson 
Tested-by: Tom Jackson 
Signed-off-by: Dan Williams 
Signed-off-by: James Bottomley 
Signed-off-by: Greg Kroah-Hartman

SCSI: Fix error handling when no ULD is attached

2012-04-15T18:08:53+00:00

Commit 18a4d0a22ed6 ("[SCSI] Handle disk devices which can not process
medium access commands") introduced a bug in which we would attempt to
dereference the scsi driver even when the device had no ULD attached.

Ensure that a driver is registered and make the driver accessor function
more resilient to errors during device discovery.

Reported-by: Elric Fu 
Reported-by: Bart Van Assche 
Signed-off-by: Martin K. Petersen 
Signed-off-by: Linus Torvalds

[SCSI] Handle disk devices which can not process medium access commands

2012-02-19T16:14:52+00:00

We have experienced several devices which fail in a fashion we do not
currently handle gracefully in SCSI. After a failure these devices will
respond to the SCSI primary command set (INQUIRY, TEST UNIT READY, etc.)
but any command accessing the storage medium will time out.

The following patch adds an callback that can be used by upper level
drivers to inspect the results of an error handling command. This in
turn has been used to implement additional checking in the SCSI disk
driver.

If a medium access command fails twice but TEST UNIT READY succeeds both
times in the subsequent error handling we will offline the device. The
maximum number of failed commands required to take a device offline can
be tweaked in sysfs.

Also add a new error flag to scsi_debug which allows this scenario to be
easily reproduced.

[jejb: fix up integer parsing to use kstrtouint]
Signed-off-by: Martin K. Petersen 
Signed-off-by: James Bottomley

[SCSI] scsi_error: classify some ILLEGAL_REQUEST sense as a permanent TARGET_ERROR

2012-02-19T15:39:59+00:00

Permanent target failures are non-retryable and should be classified as
TARGET_ERROR; otherwise dm-multipath will retry an IO request that will
always fail at the target.

A SCSI command that fails with ILLEGAL_REQUEST sense and Additional
sense 0x20, 0x21, 0x24 or 0x26 represents a permanent TARGET_ERROR.

Signed-off-by: Mike Snitzer 
Signed-off-by: James Bottomley

[SCSI] fix the new host byte settings (DID_TARGET_FAILURE and DID_NEXUS_FAILURE)

2012-02-19T14:08:59+00:00

This patch fixes the host byte settings DID_TARGET_FAILURE and
DID_NEXUS_FAILURE.  The function __scsi_error_from_host_byte, tries to reset
the host byte to DID_OK. But that does not happen because of the OR operation.

Here is the flow.

scsi_softirq_done-> scsi_decide_disposition -> __scsi_error_from_host_byte

Let's take an example with DID_NEXUS_FAILURE. In scsi_decide_disposition,
result will be set as DID_NEXUS_FAILURE (=0x11). Then in
__scsi_error_from_host_byte, when we do OR with DID_OK.  Purpose is to reset
it back to DID_OK. But that does not happen.  This patch fixes this issue.

Signed-off-by: Babu Moger 
Signed-off-by: James Bottomley

[SCSI] add flag to skip the runtime PM calls on the host

2012-01-09T00:14:57+00:00

With previous change, now the ata port runtime suspend will happen as:

disk suspend --> scsi target suspend --> scsi host suspend --> ata port
suspend

ata port(parent device) suspend need to schedule scsi EH which will resume
scsi host(child device). Then the child device resume will in turn make
parent device resume first. This is kind of recursive.

This patch adds a new flag Scsi_Host::eh_noresume.
ata port will set this flag to skip the runtime PM calls on scsi host.

Acked-by: Alan Stern 
Signed-off-by: Lin Ming 
Signed-off-by: Jeff Garzik

[SCSI] Fix out of spec CD-ROM problem with media change

2011-08-27T14:36:41+00:00

Some CD-ROMs fail to report a media change correctly.  The specific
one for this patch simply fails to respond to commands, then gives a
UNIT ATTENTION after being reset which returns ASC/ASCQ 28/00.  This
is out of spec behaviour, but add a check in the eat CC/UA on reset
path to catch this case so the CD-ROM will function somewhat properly.

[jejb: fixed up white space and accepted without signoff]
Signed-off-by: James Bottomley

[SCSI] Reduce error recovery time by reducing use of TURs

2011-05-24T16:51:53+00:00

In error recovery, most scsi error recovery stages will send a TUR command
for every bad command when a driver's error handler reports success.  When
several bad commands to the same device, this results in a device
being probed multiple times.

This becomes very problematic if the device or connection is in a state
where the device still doesn't respond to commands even after a recovery
function returns success.  The error handler must wait for the test
commands to time out.  The time waiting for the redundant commands can
drastically lengthen error recovery.

This patch alters the scsi mid-layer's error routines to send test commands
once per device instead of once per bad command.  This can drastically
lower error recovery time.

[jejb: fixed up whitespace and formatting]
Signed-of-by: David Jeffery 
Signed-off-by: James Bottomley

[SCSI] Log thin provisioning threshold event

2011-04-15T21:29:25+00:00

At least log the message that we received a THIN PROVISIONING SOFT
THRESHOLD REACHED Unit Attention.  Also added it to unit attention
decodes.

Signed-off-by: Shyam Iyer 
Signed-off-by: James Bottomley