Commit Graph

42 Commits

Author SHA1 Message Date
Dan Williams fbabd829fe acpi, nfit: fix module unload vs workqueue shutdown race
The workqueue may still be running when the devres callbacks start
firing to deallocate an acpi_nfit_desc instance. Stop and flush the
workqueue before letting any other devres de-allocations proceed.

Reported-by: Linda Knippers <linda.knippers@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-18 10:55:37 -07:00
Dan Williams 8b06b884cd tools/testing/nvdimm: fix nfit_test shutdown crash
Keep the nfit_test instances alive until after nfit_test_teardown(), as
we may be doing resource lookups until the final un-registrations have
completed. This fixes crashes of the form.

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
 IP: __release_resource+0x12/0x90
 Call Trace:
  remove_resource+0x23/0x40
  __wrap_remove_resource+0x29/0x30 [nfit_test_iomap]
  acpi_nfit_remove_resource+0xe/0x10 [nfit]
  devm_action_release+0xf/0x20
  release_nodes+0x16d/0x2b0
  devres_release_all+0x3c/0x60
  device_release+0x21/0x90
  kobject_release+0x6a/0x170
  kobject_put+0x2f/0x60
  put_device+0x17/0x20
  platform_device_unregister+0x20/0x30
  nfit_test_exit+0x36/0x960 [nfit_test]

Reported-by: Linda Knippers <linda.knippers@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-18 10:26:09 -07:00
Dan Williams ac40b675c7 tools/testing/nvdimm: test acpi 6.1 health state flags
Add a simulated dimm with an ACPI_NFIT_MEM_MAP_FAILED indication, and
set the ACPI_NFIT_MEM_HEALTH_ENABLED flag on all the dimms where
nfit_test simulates health events, but spread it out over several
redundant memdev entries to test that the nfit driver coalesces all the
flags.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-17 12:34:17 -07:00
Dan Williams df06a2d577 tools/testing/nvdimm: make iset cookie predictable
For testing changes to the iset cookie algorithm we need a value that is
constant from run-to-run.

Stop including dynamic data in the emulated region_offset values. Also,
pick values that sort in a different order depending on whether the
comparison is a memcmp() of two 8-byte arrays or subtraction of two
64-bit values.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-03-01 00:09:51 -08:00
Dan Williams c44ef859ce Merge branch 'for-4.10/libnvdimm' into libnvdimm-for-next 2016-12-17 15:08:10 -08:00
Dan Williams a7de92dac9 tools/testing/nvdimm: unit test acpi_nfit_ctl()
A recent flurry of bug discoveries in the nfit driver's DSM marshalling
routine has highlighted the fact that we do not have unit test coverage
for this routine. Add a self-test of acpi_nfit_ctl() routine before
probing the "nfit_test.0" device. This mocks stimulus to acpi_nfit_ctl()
and if any of the tests fail "nfit_test.0" will be unavailable causing
the rest of the tests to not run / fail.

This unit test will also be a place to land reproductions of quirky BIOS
behavior discovered in the field and ensure the kernel does not regress
against implementations it has seen in practice.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-12-06 17:42:36 -08:00
Dan Williams dafb104874 tools/testing/nvdimm: dynamic label support
Update nfit_test infrastructure to enable labels for the dimm on the
nfit_test.1 bus.  This bus has a pmem region without aliased blk space,
so it is a candidate for dynamically enabling label support by writing
a namespace index block.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-10-19 08:57:33 -07:00
Dan Williams 178d6f4be8 Merge branch 'for-4.9/libnvdimm' into libnvdimm-for-next 2016-10-07 16:46:24 -07:00
Dan Williams bd4cd745b3 tools/testing/nvdimm: support for sub-dividing a pmem region
Update nfit_test to handle multiple sub-allocations within a given pmem
region.  The mock resource now tracks and un-tracks sub-ranges as they
are requested and released (either explicitly or via devm callback).

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-10-07 09:20:53 -07:00
Dan Williams 73606afd46 tools/testing/nvdimm: test get_config_size DSM failures
Add an nfit_test specific attribute for gating whether a get_config_size
DSM, or any DSM for that matter, succeeds or fails.  The get_config_size
DSM is initial motivation since that is the first command libnvdimm core
issues to determine the state of the namespace label area.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-09-21 09:36:36 -07:00
Dan Williams 9d15ce9caa tools/testing/nvdimm: fix allocation range for mock flush hint tables
Commit 480b6837aa "nvdimm: fix PHYS_PFN/PFN_PHYS mixup" identified
that we were passing an invalid address to devm_nvdimm_ioremap(). With
that fixed it exposed a bug in the memory reservation size for flush
hint tables.  Since we map a full page we need to mock a full page of
memory to back the flush hint table entries.

Cc: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-09-19 13:49:48 -07:00
Dan Williams 231bf117aa tools/testing/nvdimm: unit test for acpi_nvdimm_notify()
Trigger an nmemX/nfit/flags attribute to fire an event whenever a
smart-threshold DSM is received.

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-09-01 18:20:14 -07:00
Dan Williams c14a868a5a tools/testing/nvdimm: unit test for acpi_nfit_notify()
We have had a couple bugs in this implementation in the past and before
we add another ->notify() implementation for nvdimm devices, lets allow
this routine to be exercised via nfit_test.

Rewrite acpi_nfit_notify() in terms of a generic struct device and
acpi_handle parameter, and then implement a mock acpi_evaluate_object()
that returns a _FIT payload.

Cc: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-08-23 07:49:42 -07:00
Dan Williams d8d378fa1a tools/testing/nvdimm: fix SIGTERM vs hotplug crash
The unit tests crash when hotplug races the previous probe. This race
requires that the loading of the nfit_test module be terminated with
SIGTERM, and the module to be unloaded while the ars scan is still
running.

In contrast to the normal nfit driver, the unit test calls
acpi_nfit_init() twice to simulate hotplug, whereas the nominal case
goes through the acpi_nfit_notify() event handler.  The
acpi_nfit_notify() path is careful to flush the previous region
registration before servicing the hotplug event. The unit test was
missing this guarantee.

 BUG: unable to handle kernel NULL pointer dereference at           (null)
 IP: [<ffffffff810cdce7>] pwq_activate_delayed_work+0x47/0x170
 [..]
 Call Trace:
  [<ffffffff810ce186>] pwq_dec_nr_in_flight+0x66/0xa0
  [<ffffffff810ce490>] process_one_work+0x2d0/0x680
  [<ffffffff810ce331>] ? process_one_work+0x171/0x680
  [<ffffffff810ce88e>] worker_thread+0x4e/0x480
  [<ffffffff810ce840>] ? process_one_work+0x680/0x680
  [<ffffffff810ce840>] ? process_one_work+0x680/0x680
  [<ffffffff810d5343>] kthread+0xf3/0x110
  [<ffffffff8199846f>] ret_from_fork+0x1f/0x40
  [<ffffffff810d5250>] ? kthread_create_on_node+0x230/0x230

Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-08-10 15:59:09 -07:00
Dan Williams 58cd71b474 nfit, tools/testing/nvdimm/: unify shutdown paths
While testing the new on-demand ARS patches we discovered that
differences between the nfit_test and normal nfit driver shutdown paths
can leak resources.  Unify the shutdown paths to trigger via a devm_
callback when the acpi_desc->dev is unbound from its driver.

Reviewed-by: Lee, Chun-Yi <jlee@suse.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-22 13:35:54 -07:00
Dan Williams bc9775d869 libnvdimm: move ->module to struct nvdimm_bus_descriptor
Let the provider module be explicitly passed in rather than implicitly
assumed by the module that calls nvdimm_bus_register().  This is in
preparation for unifying the nfit and nfit_test driver teardown paths.

Reviewed-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-21 20:03:19 -07:00
Dan Williams e7a11b449e nfit: cleanup acpi_nfit_init calling convention
Pass the nfit buffer as a parameter rather than hanging it off of
acpi_desc.

Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-21 14:12:18 -07:00
Dan Williams 5dc68e5574 tools/testing/nvdimm: add manufacturing_{date|location} dimm properties
New for ACPI 6.1, these fields are used in the common dimm
representation format defined by section 5.2.25.9 "NVDIMM representation
format".

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-21 14:12:18 -07:00
Dan Williams 7bfe97c763 tools/testing/nvdimm: add virtual ramdisk range
Test the virtual disk ranges that platform firmware like EDK2/OVMF might
emit.

Tested-by: "Lee, Chun-Yi" <jlee@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-21 14:12:18 -07:00
Dan Williams 85d3fa02e4 tools/testing/nvdimm: simulate multiple flush hints per-dimm
Sample nfit data to test the kernel's handling of the multiple
flush-hint case.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-11 16:13:41 -07:00
Dan Williams ee8520fe8c tools/testing/nvdimm: replace CONFIG_DMA_CMA dependency with vmalloc()
DMA_CMA is incompatible with SWIOTLB used in enterprise distro
configurations.  Switch to vmalloc() allocations for all resources.

Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-06-27 11:40:46 -07:00
Dan Williams 1f716d05f8 Merge branch 'for-4.7/dsm' into libnvdimm-for-next 2016-05-18 10:06:59 -07:00
Dan Williams 6634fb0690 tools/testing/nvdimm: ND_CMD_CALL support
Enable nfit_test to use nd_cmd_pkg marshaling.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-05-05 19:02:45 -07:00
Dan Williams e3654eca70 nfit, libnvdimm: clarify "commands" vs "_DSMs"
Clarify the distinction between "commands", the ioctls userspace calls
to request the kernel take some action on a given dimm device, and
"_DSMs", the actual function numbers used in the firmware interface to
the DIMM.  _DSMs are ACPI specific whereas commands are Linux kernel
generic.

This is in preparation for breaking the 1:1 implicit relationship
between the kernel ioctl number space and the firmware specific function
numbers.

Cc: Jerry Hoemann <jerry.hoemann@hpe.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-04-28 16:23:16 -07:00
Dan Williams baa51277cf libnvdimm, test: add mock SMART data payload
Provide simulated SMART data to enable the ndctl implementation of SMART
data retrieval and parsing.

The payload is defined here, "Section 4.1 SMART and Health Info
(Function Index 1)":

    http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-04-11 11:11:14 -07:00
Dan Williams d4f323672a nfit, libnvdimm: clear poison command support
Add the boiler-plate for a 'clear error' command based on section
9.20.7.6 "Function Index 4 - Clear Uncorrectable Error" from the ACPI
6.1 specification, and add a reference implementation in nfit_test.

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-03-05 18:06:14 -08:00
Dan Williams f471f1a7d0 tools/testing/nvdimm: expand ars unit testing
Simulate platform-firmware-initiated and asynchronous scrub results.
This injects poison in the middle of all nfit_test pmem address ranges.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-03-05 12:24:06 -08:00
Dan Williams a61fe6f790 nfit, tools/testing/nvdimm: unify common init for acpi_nfit_desc
The nvdimm unit test infrastructure performs its own initialization of
an acpi_nfit_desc to specify test overrides over the native
implementation.  Make it clear which attributes and operations it is
overriding by re-using acpi_nfit_init_desc() as a common starting point.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-03-05 12:24:06 -08:00
Dan Williams aef2533822 libnvdimm, nfit: centralize command status translation
The return value from an 'ndctl_fn' reports the command execution
status, i.e. was the command properly formatted and was it successfully
submitted to the bus provider.  The new 'cmd_rc' parameter allows the bus
provider to communicate command specific results, translated into
common error codes.

Convert the ARS commands to this scheme to:

1/ Consolidate status reporting

2/ Prepare for for expanding ars unit test cases

3/ Make the implementation more generic

Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-03-05 12:24:06 -08:00
Dan Williams 3b87356f50 nfit, tools/testing/nvdimm: test multiple control regions per-dimm
ACPI 6.1 clarifies that "The system shall include an NVDIMM Control
Region Structure for every Function Interface in the NVDIMM."
Implement this clarification in nfit_test.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-03-05 12:24:06 -08:00
Dan Williams be26f9ae02 nfit, tools/testing/nvdimm: add format interface code definitions
ACPI 6.1 and JEDEC Annex L Release 3 formalize the format interface
code.  Add definitions and update their usage in the unit test.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-03-05 12:24:06 -08:00
Dan Williams 747ffe11b4 libnvdimm, tools/testing/nvdimm: fix 'ars_status' output buffer sizing
Use the output length specified in the command to size the receive
buffer rather than the arbitrary 4K limit.

This bug was hiding the fact that the ndctl implementation of
ndctl_bus_cmd_new_ars_status() was not specifying an output buffer size.

Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-02-19 15:21:52 -08:00
Dan Williams d26f73f083 nfit_test: Enable DSMs for all test NFITs
In preparation for getting a poison list using ARS DSMs, enable DSMs for
all manufactured NFITs supplied by the test framework.  Also, supply
valid response data for ars_status.

Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-01-09 08:39:03 -08:00
Linda Knippers 6b577c9d77 nfit: Adjust for different _FIT and NFIT headers
When support for _FIT was added, the code presumed that the data
returned by the _FIT method is identical to the NFIT table, which
starts with an acpi_table_header.  However, the _FIT is defined
to return a data in the format of a series of NFIT type structure
entries and as a method, has an acpi_object header rather tahn
an acpi_table_header.

To address the differences, explicitly save the acpi_table_header
from the NFIT, since it is accessible through /sys, and change
the nfit pointer in the acpi_desc structure to point to the
table entries rather than the headers.

Reported-by: Jeff Moyer (jmoyer@redhat.com>
Signed-off-by: Linda Knippers <linda.knippers@hpe.com>
Acked-by: Vishal Verma <vishal.l.verma@intel.com>
[vishal: fix up unit test for new header assumptions]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-11-30 14:51:46 -08:00
Dan Williams f42957967f tools/testing/nvdimm, acpica: fix flag rename build breakage
Commit ca321d1ca6 "ACPICA: Update NFIT table to rename a flags field"
performed a tree-wide s/ACPI_NFIT_MEM_ARMED/ACPI_NFIT_MEM_NOT_ARMED/
operation, but missed the tools/testing/nvdimm/ directory.

Cc: Bob Moore <robert.moore@intel.com>
Cc: Lv Zheng <lv.zheng@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-11-12 09:21:18 -08:00
Vishal Verma 209851649d acpi: nfit: Add support for hot-add
Add a .notify callback to the acpi_nfit_driver that gets called on a
hotplug event. From this, evaluate the _FIT ACPI method which returns
the updated NFIT with handles for the hot-plugged NVDIMM.

Iterate over the new NFIT, and add any new tables found, and
register/enable the corresponding regions.

In the nfit test framework, after normal initialization, update the NFIT
with a new hot-plugged NVDIMM, and directly call into the driver to
update its view of the available regions.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Elliott, Robert <elliott@hpe.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: <linux-acpi@vger.kernel.org>
Cc: <linux-nvdimm@lists.01.org>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-11-02 15:28:07 -05:00
Ross Zwisler 67a3e8fe90 nd_blk: change aperture mapping from WC to WB
This should result in a pretty sizeable performance gain for reads.  For
rough comparison I did some simple read testing using PMEM to compare
reads of write combining (WC) mappings vs write-back (WB).  This was
done on a random lab machine.

PMEM reads from a write combining mapping:
	# dd of=/dev/null if=/dev/pmem0 bs=4096 count=100000
	100000+0 records in
	100000+0 records out
	409600000 bytes (410 MB) copied, 9.2855 s, 44.1 MB/s

PMEM reads from a write-back mapping:
	# dd of=/dev/null if=/dev/pmem0 bs=4096 count=1000000
	1000000+0 records in
	1000000+0 records out
	4096000000 bytes (4.1 GB) copied, 3.44034 s, 1.2 GB/s

To be able to safely support a write-back aperture I needed to add
support for the "read flush" _DSM flag, as outlined in the DSM spec:

http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

This flag tells the ND BLK driver that it needs to flush the cache lines
associated with the aperture after the aperture is moved but before any
new data is read.  This ensures that any stale cache lines from the
previous contents of the aperture will be discarded from the processor
cache, and the new data will be read properly from the DIMM.  We know
that the cache lines are clean and will be discarded without any
writeback because either a) the previous aperture operation was a read,
and we never modified the contents of the aperture, or b) the previous
aperture operation was a write and we must have written back the dirtied
contents of the aperture to the DIMM before the I/O was completed.

In order to add support for the "read flush" flag I needed to add a
generic routine to invalidate cache lines, mmio_flush_range().  This is
protected by the ARCH_HAS_MMIO_FLUSH Kconfig variable, and is currently
only supported on x86.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-08-27 19:38:28 -04:00
Vishal Verma 39c686b862 libnvdimm: Add DSM support for Address Range Scrub commands
Add support for the three ARS DSM commands:
- Query ARS Capabilities - Queries the firmware to check if a given
  range supports scrub, and if so, which type (persistent vs. volatile)
- Start ARS - Starts a scrub for a given range/type
- Query ARS Status - Checks status of a previously started scrub, and
  provides the error logs if any.

  The commands are described by the example DSM spec at:
  http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

Also add these commands to the nfit_test test framework, and return
canned data.

Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-07-27 22:53:19 -04:00
Dan Williams 9d27a87ec9 tools/testing/nvdimm: add mock acpi_nfit_flush_address entries to nfit_test
In preparation for fixing the BLK path to properly use "directed
pcommit" enable the unit test infrastructure to emit mock "flush"
tables.  Writes to these flush addresses trigger a memory controller to
flush its internal buffers to persistent media, similar to the x86
"pcommit" instruction.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-07-10 14:07:03 -04:00
Dan Williams f7ec83684a tools/testing/nvdimm: fix return code for unimplemented commands
The implementation for the new "DIMM Flags" DSM relies on the -ENOTTY
return code to indicate that the flags are unimplimented and to fall
back to a safe default.  As is the -ENXIO error code erroneoously
indicates to fail enabling a BLK region.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-07-10 13:50:50 -04:00
Dan Williams 5813882094 libnvdimm, nfit: handle unarmed dimms, mark namespaces read-only
Upon detection of an unarmed dimm in a region, arrange for descendant
BTT, PMEM, or BLK instances to be read-only.  A dimm is primarily marked
"unarmed" via flags passed by platform firmware (NFIT).

The flags in the NFIT memory device sub-structure indicate the state of
the data on the nvdimm relative to its energy source or last "flush to
persistence".  For the most part there is nothing the driver can do but
advertise the state of these flags in sysfs and emit a message if
firmware indicates that the contents of the device may be corrupted.
However, for the case of ACPI_NFIT_MEM_ARMED, the driver can arrange for
the block devices incorporating that nvdimm to be marked read-only.
This is a safe default as the data is still available and new writes are
held off until the administrator either forces read-write mode, or the
energy source becomes armed.

A 'read_only' attribute is added to REGION devices to allow for
overriding the default read-only policy of all descendant block devices.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-26 11:23:38 -04:00
Dan Williams 6bc756193f tools/testing/nvdimm: libnvdimm unit test infrastructure
'libnvdimm' is the first driver sub-system in the kernel to implement
mocking for unit test coverage.  The nfit_test module gets built as an
external module and arranges for external module replacements of nfit,
libnvdimm, nd_pmem, and nd_blk.  These replacements use the linker
--wrap option to redirect calls to ioremap() + request_mem_region() to
custom defined unit test resources.  The end result is a fully
functional nvdimm_bus, as far as userspace is concerned, but with the
capability to perform otherwise destructive tests on emulated resources.

Q: Why not use QEMU for this emulation?
QEMU is not suitable for unit testing.  QEMU's role is to faithfully
emulate the platform.  A unit test's role is to unfaithfully implement
the platform with the goal of triggering bugs in the corners of the
sub-system implementation.  As bugs are discovered in platforms, or the
sub-system itself, the unit tests are extended to backstop a fix with a
reproducer unit test.

Another problem with QEMU is that it would require coordination of 3
software projects instead of 2 (kernel + libndctl [1]) to maintain and
execute the tests.  The chances for bit rot and the difficulty of
getting the tests running goes up non-linearly the more components
involved.


Q: Why submit this to the kernel tree instead of external modules in
   libndctl?
Simple, to alleviate the same risk that out-of-tree external modules
face.  Updates to drivers/nvdimm/ can be immediately evaluated to see if
they have any impact on tools/testing/nvdimm/.


Q: What are the negative implications of merging this?
It is a unique maintenance burden because the purpose of mocking an
interface to enable a unit test is to purposefully short circuit the
semantics of a routine to enable testing.  For example
__wrap_ioremap_cache() fakes the pmem driver into "ioremap()'ing" a test
resource buffer allocated by dma_alloc_coherent().  The future
maintenance burden hits when someone changes the semantics of
ioremap_cache() and wonders what the implications are for the unit test.

[1]: https://github.com/pmem/ndctl

Cc: <linux-acpi@vger.kernel.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-26 11:23:38 -04:00