linux-stable.git/drivers/scsi/hosts.c, branch linux-4.2.y

scsi: remove ordered_tag host template field

2014-11-12T10:19:41+00:00

Signed-off-by: Christoph Hellwig 
Reviewed-by: Bart Van Assche 
Reviewed-by: Mike Christie 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Hannes Reinecke

scsi: fixup logging messages in scsi_error.c

2014-11-12T10:16:06+00:00

Use the matching scope for logging messages to allow for
better command tracing.

Signed-off-by: Hannes Reinecke 
Suggested-by: Robert Elliott 
Reviewed-by: Robert Elliott 
Signed-off-by: Christoph Hellwig

scsi: add support for a blk-mq based I/O path.

2014-07-25T21:16:28+00:00

This patch adds support for an alternate I/O path in the scsi midlayer
which uses the blk-mq infrastructure instead of the legacy request code.

Use of blk-mq is fully transparent to drivers, although for now a host
template field is provided to opt out of blk-mq usage in case any unforseen
incompatibilities arise.

In general replacing the legacy request code with blk-mq is a simple and
mostly mechanical transformation.  The biggest exception is the new code
that deals with the fact the I/O submissions in blk-mq must happen from
process context, which slightly complicates the I/O completion handler.
The second biggest differences is that blk-mq is build around the concept
of preallocated requests that also include driver specific data, which
in SCSI context means the scsi_cmnd structure.  This completely avoids
dynamic memory allocations for the fast path through I/O submission.

Due the preallocated requests the MQ code path exclusively uses the
host-wide shared tag allocator instead of a per-LUN one.  This only
affects drivers actually using the block layer provided tag allocator
instead of their own.  Unlike the old path blk-mq always provides a tag,
although drivers don't have to use it.

For now the blk-mq path is disable by defauly and must be enabled using
the "use_blk_mq" module parameter.  Once the remaining work in the block
layer to make blk-mq more suitable for slow devices is complete I hope
to make it the default and eventually even remove the old code path.

Based on the earlier scsi-mq prototype by Nicholas Bellinger.

Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and
various sugestions and code contributions.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Hannes Reinecke 
Reviewed-by: Webb Scales 
Acked-by: Jens Axboe 
Tested-by: Bart Van Assche 
Tested-by: Robert Elliott

scsi: use dev_printk variants where possible

2014-07-17T20:07:42+00:00

Using dev_printk variants prefixes the logging message with
the originating device, which makes debugging easier.

Signed-off-by: Hannes Reinecke 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Christoph Hellwig

[SCSI] scsi_error: disable eh_deadline if no host_reset_handler is set

2014-03-15T17:18:59+00:00

When the host template doesn't declare an eh_host_reset_handler
the eh_deadline mechanism is pointless and will set the
device to offline. So disable eh_deadline if no
eh_host_reset_handler is present.

Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Set the minimum valid value of 'eh_deadline' as 0

2013-12-19T15:39:02+00:00

The former minimum valid value of 'eh_deadline' is 1s, which means
the earliest occasion to shorten EH is 1 second later since a
command is failed or timed out. But if we want to skip EH steps
ASAP, we have to wait until the first EH step is finished. If the
duration of the first EH step is long, this waiting time is
excruciating. So, it is necessary to accept 0 as the minimum valid
value for 'eh_deadline'.

According to my test, with Hannes' patchset 'New EH command timeout
handler' as well, the minimum IO time is improved from 73s
(eh_deadline = 1) to 43s(eh_deadline = 0) when commands are timed
out by disabling RSCN and target port.

Signed-off-by: Ren Mingxin 
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] improved eh timeout handler

2013-12-19T15:39:02+00:00

When a command runs into a timeout we need to send an 'ABORT TASK'
TMF. This is typically done by the 'eh_abort_handler' LLDD callback.

Conceptually, however, this function is a normal SCSI command, so
there is no need to enter the error handler.

This patch implements a new scsi_abort_command() function which
invokes an asynchronous function scsi_eh_abort_handler() to
abort the commands via the usual 'eh_abort_handler'.

If abort succeeds the command is either retried or terminated,
depending on the number of allowed retries. However, 'eh_eflags'
records the abort, so if the retry would fail again the
command is pushed onto the error handler without trying to
abort it (again); it'll be cleared up from SCSI EH.

[hare: smatch detected stray switch fixed]
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Disable WRITE SAME for RAID and virtual host adapter drivers

2013-11-29T04:48:39+00:00

Some host adapters do not pass commands through to the target disk
directly. Instead they provide an emulated target which may or may not
accurately report its capabilities. In some cases the physical device
characteristics are reported even when the host adapter is processing
commands on the device's behalf. This can lead to adapter firmware hangs
or excessive I/O errors.

This patch disables WRITE SAME for devices connected to host adapters
that provide an emulated target. Driver writers can disable WRITE SAME
by setting the no_write_same flag in the host adapter template.

[jejb: fix up rejections due to eh_deadline patch]
Signed-off-by: Martin K. Petersen 
Cc: stable@kernel.org
Signed-off-by: James Bottomley

[SCSI] Add 'eh_deadline' to limit SCSI EH runtime

2013-10-25T11:17:59+00:00

This patchs adds an 'eh_deadline' sysfs attribute to the scsi
host which limits the overall runtime of the SCSI EH.
The 'eh_deadline' value is stored in the now obsolete field
'resetting'.
When a command is failed the start time of the EH is stored
in 'last_reset'. If the overall runtime of the SCSI EH is longer
than last_reset + eh_deadline, the EH is short-circuited and
falls through to issue a host reset only.

[jejb: add comments in Scsi_Host about new fields]
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

driver-core: constify data for class_find_device()

2013-02-06T20:18:56+00:00

All in-kernel users of class_find_device() don't really need mutable
data for match callback.

In two places (kernel/power/suspend_test.c, drivers/scsi/osd/osd_uld.c)
this patch changes match callbacks to use const search data.

The const is propagated to rtc_class_open() and power_supply_get_by_name()
parameters.

Note that there's a dev reference leak in suspend_test.c that's not
touched in this patch.

Signed-off-by: Michał Mirosław 
Acked-by: Grant Likely 
Signed-off-by: Greg Kroah-Hartman