From 6bc756193ff61bf5e7b3cfedfbb0873bf40f8055 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 17 Jun 2015 17:23:32 -0400 Subject: 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: Cc: Lv Zheng Cc: Robert Moore Cc: Rafael J. Wysocki Cc: Christoph Hellwig Signed-off-by: Dan Williams --- drivers/acpi/nfit.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'drivers/acpi/nfit.c') 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; -- cgit v1.2.3