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author | Dan Williams <dan.j.williams@intel.com> | 2015-06-17 17:23:32 -0400 |
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committer | Dan Williams <dan.j.williams@intel.com> | 2015-06-26 11:23:38 -0400 |
commit | 6bc756193ff61bf5e7b3cfedfbb0873bf40f8055 (patch) | |
tree | 5b17fac71bf9989eb2f5ab4ff10e3c6fc01a3cbf /tools/testing/nvdimm/test/nfit_test.h | |
parent | 047fc8a1f9a6330eacc80374dff087e20dc2304b (diff) | |
download | linux-6bc756193ff61bf5e7b3cfedfbb0873bf40f8055.tar.bz2 |
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 'tools/testing/nvdimm/test/nfit_test.h')
-rw-r--r-- | tools/testing/nvdimm/test/nfit_test.h | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/tools/testing/nvdimm/test/nfit_test.h b/tools/testing/nvdimm/test/nfit_test.h new file mode 100644 index 000000000000..96c5e16d7db9 --- /dev/null +++ b/tools/testing/nvdimm/test/nfit_test.h @@ -0,0 +1,29 @@ +/* + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#ifndef __NFIT_TEST_H__ +#define __NFIT_TEST_H__ + +struct nfit_test_resource { + struct list_head list; + struct resource *res; + struct device *dev; + void *buf; +}; + +typedef struct nfit_test_resource *(*nfit_test_lookup_fn)(resource_size_t); +void __iomem *__wrap_ioremap_nocache(resource_size_t offset, + unsigned long size); +void __wrap_iounmap(volatile void __iomem *addr); +void nfit_test_setup(nfit_test_lookup_fn lookup); +void nfit_test_teardown(void); +#endif |