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author | Dan Williams <dan.j.williams@intel.com> | 2015-06-17 23:23:32 +0200 |
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committer | Dan Williams <dan.j.williams@intel.com> | 2015-06-26 17:23:38 +0200 |
commit | 6bc756193ff61bf5e7b3cfedfbb0873bf40f8055 (patch) | |
tree | 5b17fac71bf9989eb2f5ab4ff10e3c6fc01a3cbf /drivers | |
parent | libnvdimm, nfit, nd_blk: driver for BLK-mode access persistent memory (diff) | |
download | linux-6bc756193ff61bf5e7b3cfedfbb0873bf40f8055.tar.xz linux-6bc756193ff61bf5e7b3cfedfbb0873bf40f8055.zip |
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>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/acpi/nfit.c | 12 | ||||
-rw-r--r-- | drivers/acpi/nfit.h | 6 |
2 files changed, 14 insertions, 4 deletions
diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c index 2aa6aa97b40c..07d630e9f4ae 100644 --- a/drivers/acpi/nfit.c +++ b/drivers/acpi/nfit.c @@ -33,10 +33,11 @@ MODULE_PARM_DESC(force_enable_dimms, "Ignore _STA (ACPI DIMM device) status"); static u8 nfit_uuid[NFIT_UUID_MAX][16]; -static const u8 *to_nfit_uuid(enum nfit_uuids id) +const u8 *to_nfit_uuid(enum nfit_uuids id) { return nfit_uuid[id]; } +EXPORT_SYMBOL(to_nfit_uuid); static struct acpi_nfit_desc *to_acpi_nfit_desc( struct nvdimm_bus_descriptor *nd_desc) @@ -581,11 +582,12 @@ static struct attribute_group acpi_nfit_attribute_group = { .attrs = acpi_nfit_attributes, }; -static const struct attribute_group *acpi_nfit_attribute_groups[] = { +const struct attribute_group *acpi_nfit_attribute_groups[] = { &nvdimm_bus_attribute_group, &acpi_nfit_attribute_group, NULL, }; +EXPORT_SYMBOL_GPL(acpi_nfit_attribute_groups); static struct acpi_nfit_memory_map *to_nfit_memdev(struct device *dev) { @@ -1323,7 +1325,7 @@ static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc, ndbr_desc = to_blk_region_desc(ndr_desc); ndbr_desc->enable = acpi_nfit_blk_region_enable; ndbr_desc->disable = acpi_nfit_blk_region_disable; - ndbr_desc->do_io = acpi_nfit_blk_region_do_io; + ndbr_desc->do_io = acpi_desc->blk_do_io; if (!nvdimm_blk_region_create(acpi_desc->nvdimm_bus, ndr_desc)) return -ENOMEM; break; @@ -1407,7 +1409,7 @@ static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc) return 0; } -static int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz) +int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz) { struct device *dev = acpi_desc->dev; const void *end; @@ -1446,6 +1448,7 @@ static int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz) return acpi_nfit_register_regions(acpi_desc); } +EXPORT_SYMBOL_GPL(acpi_nfit_init); static int acpi_nfit_add(struct acpi_device *adev) { @@ -1470,6 +1473,7 @@ static int acpi_nfit_add(struct acpi_device *adev) dev_set_drvdata(dev, acpi_desc); acpi_desc->dev = dev; acpi_desc->nfit = (struct acpi_table_nfit *) tbl; + acpi_desc->blk_do_io = acpi_nfit_blk_region_do_io; nd_desc = &acpi_desc->nd_desc; nd_desc->provider_name = "ACPI.NFIT"; nd_desc->ndctl = acpi_nfit_ctl; diff --git a/drivers/acpi/nfit.h b/drivers/acpi/nfit.h index 7bd38b7baf39..c62fffea8423 100644 --- a/drivers/acpi/nfit.h +++ b/drivers/acpi/nfit.h @@ -93,6 +93,8 @@ struct acpi_nfit_desc { struct nvdimm_bus *nvdimm_bus; struct device *dev; unsigned long dimm_dsm_force_en; + int (*blk_do_io)(struct nd_blk_region *ndbr, resource_size_t dpa, + void *iobuf, u64 len, int rw); }; enum nd_blk_mmio_selector { @@ -146,4 +148,8 @@ static inline struct acpi_nfit_desc *to_acpi_desc( { return container_of(nd_desc, struct acpi_nfit_desc, nd_desc); } + +const u8 *to_nfit_uuid(enum nfit_uuids id); +int acpi_nfit_init(struct acpi_nfit_desc *nfit, acpi_size sz); +extern const struct attribute_group *acpi_nfit_attribute_groups[]; #endif /* __NFIT_H__ */ |